The Story
I have a high-stress job in the Information Technology field. At lunch I trade my dress shoes for walking shoes and walk my employer's campus, and several other industrial parks in the area. I use walking as a way to reduce stress, clear my mind, and prepare for tasks that need to be completed by the end of the working day.
Recently I noticed a dumpster at one of the industrial parks, and maintenance workers cleaning out a properly, readying it for the next lessee. The dumpster was only shoulder height, the style used to haul away construction waste. I glanced in the top of the dumpster as I strolled by and noticed a compete stereo system strewn of top of old lumber. The stereo system consisted of the following components: Fisher CA-273 Stereo Amplifier Fisher EQ-273 Graphic Stereo Equalizer Fisher FM-273 AM/FM Stereo Synthesizer Tuner Fisher AD-813 CD Player I could tell that the components of this stereo system had not seen the light of day in many years. I made several walking strips between the dumpster and my car until all the components of my "dumpster" stereo were safely deposited in the trunk. Although I have recovered the above stereo components, this blog is going to cover the repair of the CA-273 Stereo Amplifier only. About the Fisher CA-273 Stereo Amplifier
The Fisher CA-273 Stereo Amplifier was first introduced in 1983. It was intended to be used with FM-273 Tuner, CR-273 Cassette Deck, EQ-273 Graphic Equalizer, and MT-273 Turntable. The CA-273 Stereo Amplifier had impressive specs for the time. It could provide 100 Watts RMS power to the speaker with .09% Total Harmonic Distortion. Its audio bandwidth was between 20Hz to 20kHz. On the back it included Phono, Tuner, CD, Aux and Tape inputs. In addition, the CA-273 has two switched and one unswitched outlet so the you could provide power to other stereo components. The front of the CA-273 included input Function Selector, 3-band Tone Control, Power Level Indicators, Balance, and Volume controls.
Step 1 Initial Cleaning
My dumpster find CA-273 was covered in dust and dirt. In addition, it had been recently rained on.
I sprayed the CA-273's exterior with Windex then cleaned with paper towels. I buy Windex in "Refillable" 1 Gallon jugs as I use so much of it around the house. I then transfer Windex from the refillable jugs to generic spray bottles.
I use Windex moistened Q-Tips to clean hard to reach spots, like between the RCA jacks.
A moistened Magic Eraser sponge works great for cleaning dirty AC cords.
Look at all of the dirt Magic Eraser removed from the AC cord.
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A fine tip permanent marker works great on concealing any scraps or gouges in the top cover's paint.
I used a store brand protectant, an equivalent to Armor All, to bring out a nice sheen to the exterior plastic and metal painted parts of the CA-273.
I then used a lint free cloth to buff the exterior of the enclosure and to remove any lint deposited from the paper towels during cleaning.
Step 2 Initial Testing
Once I cleaned all of the Fisher components found in the dumpster, I connected them together via RCA cables, added speakers and an FM antenna then powered everything up. All components powered up but I noticed I was missing the left audio channel in its entirety. In addition, the CD player would not detect an audio disc, but this is material for another RadioBoatAnchor blog. In order to determine if the issue was with the CA-273 Stereo Amplifier or an external component, I switched the left and right audio cables between the FM-273 Tuner and the CA-273 Stereo Amplifier. There was still no sound from the left audio channel, indicating an issue with the CA-273 Stereo Amplifier.
Step 3 Disassembly
Disassembly was required in order to diagnose the issue with left stereo channel. The first step in the disassembly process is to remove the top metal cover. It is held in place by two screws on both sides. See areas circled in the picture below:
In addition, there is one screw, circled below, that holds the top metal cover down in the back. This screw must also be removed.
You can now access the component side of the main printed circuit board.
Four screws hold the bottom metal cover in place. See areas circled in the picture below:
You can access the foil side of the main printed circuit board, Darlington Power Packs, and the power transistors used to regulate the DC power supply, once the bottom metal cover has been removed.
Step 4 Troubleshooting
Once the top and bottom covers of the CA-273 were removed, I could start my troubleshooting. I was unable to find a free schematic on the Internet for the CA-273 so I was left to my own devices as it seemed silly to spend $25.00 on a Sam's Photofact Service manual when the amplifier was "free".
The first thing I did was check the fuses, circled in the picture below. I do a continuity check of each fuse as I have been fooled by doing visual checks before.
In my case all of the fuses checked good. Next, I swapped the Darlington Power Packs, circled in red below. The Darlington Power Packs are the semiconductor components that directly drive the speakers. I would know if a Darlington Power Pack is defective after the swap as the stereo channel problem would have migrated from the left to right channel.
The Darlington Power Pack swap is relatively easy. Two screws hold each in place. A desolder tool quickly sucks away any molten solder from the pads.
Swapping the Darlington Power Packs did not cause the issue to migrate from the left to the right channel, thereby, I must deduce that a Darlington Power Pack was not the issue. Do NOT try to swap the transistors circled below. They are part of the regulator circuit for the positive and negative DC power supplies are are NOT interchangeable.
I came up with a great idea of using the CA-273 as a Signal Tracer, in order to determine where the fault lies. I set the CA-273 on its side and powered it on. I then connected one terminal of my home brew audio generator to the CA-273 chassis and the other to the a multi-meter test lead.
I set the volume control of the CA-273 to about 75% of its travel. I then placed the tip of the multi-meter test lead, connected to my audio generator, in close proximity to components on the main printed circuit board. I would hear a tone from the audio generator, out of the left or right speaker connected to the CA-273, if their was not an issue with that circuit stage. Do NOT touch the multi-meter lead to an actual lead of a component or you may hear the audio tone at close to 100 Watts RMS!
The main printed circuit board in the CA-273 is roughly divided into three sections. The Left Audio Channel (circled in red), the Right Audio Channel (circled in yellow), and the DC Power Supply (circled in blue).
I had determined that nothing was wrong with the main printed circuit board. Circled below are connections between the main printed circuit board and printed circuit board with the volume control. The connection circled in red is for the left audio channel while the connection circled in yellow is for the right audio. I could hear the audio generator's signal from either channel if I brought the multi-meter lead close to them. The printed circuit board with the volume control feeds audio signals into the main printed circuit board.
When looking at the front of the CA-273, you will see a vertically mounted printed circuit board toward the right-hand side of the chassis. This printed circuit board handles Function selections, switching between different inputs, such as Phono, Tape, Tuner, and CD Player. The connector circled in red below connects this printed circuit board to the printed circuit board with the volume control. When I hovered my multi-meter lead over this connector. I could hear the signal generator's audio tone out of the right speaker but not the left. This indicated that the issue is on the printed circuit board with the volume control.
Knowing that mechanical controls are often a problem, especially with equipment that has been dormant for a long time, I decided to fool with the volume control to see if that was the issue. I adjusted the volume control slider to about a quarter length of its travel. I then connected my audio generator to the left channel Tuner input and played with the volume control slider knob. I found that the left channel would work if I twisted the volume control slider knob slightly. This indicated that the volume control slider carbon track for the left channel was dirty or oxidized and needed to be cleaned.
Step 5 Front Panel Removal
As I already had the CA-273 apart, I decided to disassemble the front panel. This allowed me to better concentrate the contact cleaner in the areas that needed to be cleaned. I was also afraid that the dripping contact cleaner residue could dissolve surrounding plastic parts. I also decided to clean the innards of the Tone and Balance controls as well.
In order to remove the front panel, you must first disconnect the wiring between the audio input printed circuit board and the front panel. In addition, you must disconnect the wiring between the main printed circuit board and the front panel. See areas circled in the picture below. The bezel attaches to the front panel with three screws on the bottom and at the inner lip at the top. The Function Selector switch is part of the front bezel so I had to pull the wiring through the opening in the front panel in order to free. I also had to remove the silver knobs from the three Tone Control sliders. 
Behind the front bezel is a metal panel where the volume control printed circuit board and power level indicator are installed. In order to free the metal panel you must remove several screws. There is a screw on each side, circled in the picture below:
In addition, you must remove several screws on the bottom to free the metal panel. Their locations are circled below.
Screws holding the power switch, and the printed circuit board containing the Speaker and Tone switches, need to be removed. The clip holding the headphone jack needs to be removed as well. In addition, the cream colored plastic pieces on the Speaker and Tone switches must be removed in order to free the printed circuit board from the front panel.
Here is a picture of the CA-273 front panel.
Here is a picture of the CA-273 with the front panel removed.
Step 6 Front Panel Slider Control Cleaning
Through my experience, I have learned that slider potentiometer controls don't age well. Due to their open construction, they are more prone to problems with dust and dirt than enclosed rotary ones. The next step is to free the volume control printed circuit board from the metal panel.
I removed the silver knob on the slider Volume control. The black plastic mount must also be removed, it is held in place with one screw. I also performed these same steps for Balance, the slider control to the immediate left. 
I removed ten screws that held the volume printed circuit board to the front panel. You must also remove the Tone control indicators from the slider switches. See areas circled in the picture below:
Finally, time to clean the Volume, Balance, and Tone slider controls. I sprayed a small amount of contact cleaner in each slider's slot then worked them through their complete motion several times.
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It is always a good idea to perform testing before buttoning everything up. I re-attached the volume printed circuit board to the front panel. The front panel was then fastened to the chassis and all wiring between the front panel, main, and audio input printed circuit boards were connected. The Function Selector switch is built into the front bezel. I had to connect the wiring between the front bezel and the audio input printed circuit boards.
I plugged the CA-273 into an outlet then powered it on. I then set the Function selector to Tuner, the Balance slider centered, and the Volume slider to about 1/8 of its travel. I then introduced and audio signal from my audio generator to first the left then right RCA Tuner Input jacks. SUCCESS! I was able to hear the tone first from the left then the right speaker, the issue had been resolved. 
Step 9 Detailing
I like to polish the chrome knobs before assembly. This is the perfect time to do it as the knobs have been removed from their control. Meguiar's Motorcycle All Metal Polish works great for polishing and removing oxidation from chrome coated plastic knobs, like the ones used in the CA-273.
Here is a picture of the CA-273's chrome knobs after being polished.
Meguiar's Chrome Polish on Amazon!Step 10 Assembly
Time to button the CA-273 up. I followed Step 5 Front Panel Removal, in reverse order, to assemble the front panel and attach to the CA-273 chassis. Then following Step 3 Disassembly, in reverse order, to install the top and bottom metal covers.
Step 11 Final Testing
Once the CA-273 was put back together it was time for a final test. Once again, I connected the CA-273 Stereo Amplifier to the FM-273 Tuner, EQ-273 Graphic Equalizer, and AD-318 CD Player via RCA cables. I then added speakers and an FM antenna then finally powered everything up. All components powered up and my left audio channel was once again working!
Conclusion
Bringing the Fisher CA-273 Stereo Amplifier back from the grave was a most satisfying endeavor. It is one less thing destined for a landfill. I have yet to service the AD-318 CD Player, it will be the focus of another RadioBoatAnchor blog. The remaining Fisher components grace my basement workshop and provide background music while I toil away on the next restore project.
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My Heathkit XR-1L
I was the winning bidder of the vintage Heathkit XR-1L AM Radio from an online auction site. I didn't have much competition as Heathkit Ham Radio and High Fidelity Stereo equipment are more widely sought after. My XR-1L was basically intact except that the moulded leather handle was missing.
There were scuffs and scratches on the leather case due to normal wear and tear.
There was a lot of rust and corrosion on the radio chassis, probably caused by chemicals inside dead leaking batteries left in the radio by a previous owner. The battery compartment, shown at the bottom of the picture below, was very rusty.
My Story
I have a soft spot for Heathkit radios and equipment. As a child I remember my dad being hunched over our dining room table on any given evening, building various pieces of Heathkit equipment. It was my job to inventory all of the discrete parts and to place them neatly in cardboard egg cartons we used as organizers. In addition, I would hand my dad the parts required during the assembly process. At the end of each building session, we would have to carefully move all of the parts to the top of the dresser in my parents bedroom, in order to clear the dining room table for the next meal. The dresser was high enough that it prevented my two young toddler sisters from being able to access it. My parents, two sisters, and I lived in a small three bedroom ranch in a suburb of Cleveland, there was very little extra space for hobbies, other than the dining room table. My dad and I working on Heathkit equipment brings back fond memories, as such, I have become an avid collector of vintage Heathkit equipment.
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There is a wide variety of completed Heathkit kits available on Amazon.
Step 1 Initial Testing
In order to establish a baseline of my radio's performance, I decided to power it on to see if it would pick up any stations, prior to restoration. First I removed the chassis from its leather case. Only two screws, circled in red below, hold the chassis in the case. First I had to remove the Tuning and Power/Volume knobs, they just pull off. The chassis pulls straight back and out of the back of the case, once the screws were removed.
As you can see below, the chassis of the Heathkit XR-1L AM Radio is truly a self contained unit. Even the speaker is mounted on standoffs to the component side of the chassis. This radio required 9 Volts, typically supplied by six D Cell batteries. For initial testing purposes, I used a 9 Volt battery, jumpered to the proper connections in the battery compartment to provide power. Initial testing was promising, I immediately heard atmospheric hiss once I turned the volume control to the On position and then set the volume to about midpoint of its range. With some fiddling of the tuning dial, I as able to hear a couple of stations in my regional area that I know have a strong signal. My Heathkit XR-1L was functioning, but its sensitivity left much to be desired.
Step 2 Electrolytic Capacitor Replacement
As electrolytic capacitors age, their electrolyte dries up causing their electrical capacity to drop and leakage current to increase. It is definitely a good idea to replace 60 year old electrolytic capacitors like the ones in my Heathkit XR-1L!
Electrolytic capacitors should be replaced with one of similar capacitance and equal or above Voltage rating. These type of capacitors are also polarized so make sure you observe the polarity of the capacitor to be replaced and install new the same way.
The speaker must be removed before you can reach the component side of the chassis, where the electrolytic capacitors reside. Four screws, circled in the picture below, hold the speaker to the chassis.
Once the screws have been removed, you must flip the speaker towards the top of the chassis, where the loopstick antenna is attached, so that you can gain access to the wires. You must desolder the yellow and black wires from the speaker terminal in order to remove.
Circled below in red are all of the electrolytic capacitors that need to be replaced. You must remove the Power/Volume control, circled in yellow, from the chassis to gain access to one of the electrolytic capacitors to be replaced.
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I purchase all of my replacement electrolytic capacitors, in bulk, on Amazon.
I also took this opportunity to lubricate the shaft of the Power/Volume control as its rotation was quite stiff. I use Labelle 107 Oil as it is safe on plastics and I have it around for my model train hobby.
Below is a picture of the chassis with the electrolytic capacitors replaced. I have circled the replacement capacitors in red. You'll notice that 60 years of development has led to much smaller capacitors packages. I had to change connection locations as I replaced the original axial package electronic capacitors with radial packaged ones that I keep in stock.
Once again I took the opportunity to test my Heathkit XR-1L radio after the replacement of electrolytic capacitors. I used alligator clips to temporary connect the speaker to the yellow and black audio transformer leads. In addition, I used alligator leads to connect a 9 Volt battery, used as a temporary power source. Once powered on, I noticed immediately a drastic improvement in the sensitivity of this receiver. I was able to pick up stations accross the entire AM broadcast band!
Step 3 Disassembly
The chassis of my Heathkit XR-1L radio was pretty rusted and corroded, most likely caused by corrosive chemicals emitted from dead batteries left in the radio many years ago. The only way I could make the chassis presentable again was to sand and then paint it. The first step is to remove as many components as possible from the chassis to make the masking process easier.
I removed the six transistors, they are mounted in sockets. I removed the transistors, one at a time, noting their part number and placement on the chassis.
I removed the side panels, in order to making the paint process easier. Three screws and the Power/Volume control nut must be removed in order to free the right side panel. In addition, you must desolder the solder lug connected to the white wire leading to the battery compartment, then thread the wire through the hole. Once these are removed the right side panel should be free from the chassis.
You must remove several screws on the left side panel in order to free it from the chassis.
You must also separate the adjustable bar from the left side panel. The bar has a insulated battery contact that must be removed for paint as well. It is held in place with one screw. Make note of how the insulators are placed on the screw shank.
The loopstick antenna, circled in red below, must be removed for paint. Plastic mounts on each side hold it to the chassis side plates. I noted the locations were its wire leads are soldered to components on the chassis, then desolder the wires from the antenna.
I decided to also remove the tuning capacitor from the chassis, first noting its wiring before desoldering wires connecting to it.
Next I removed both interstage and audio transformers from the chassis, first, making note of how they were wired to components on the chassis. I took the picture below after I already removed the audio transformer.
Step 4 Sanding and Polishing
It is important to remove as much rust and corrosion from the chassis and side panels as possible before paint. I used my Dremel tool with either a wire brush or sanding drum to remove the heavier rust deposits.
As a final step, all of the chassis parts were wet sanded with ultra fine 800 grit sandpaper.
As I time saving step, I typically replace rusted hardware (nuts, screws, lock washers) with new. It only adds a couple dollars to the cost of the project. Unfortunately, our local hardware store did not have the same style of slotted screws used to assemble the Heathkit XR-1L chassis.
Instead, I used my cordless drill, Meguiar's Motorcycle All Metal Polish, and paper towels to shine the screw heads. I would insert the shaft of the screw in the drill's chuck then tighten it down firmly. I would then apply a dab of polish to the paper towel. I would press the paper towel with polish against the screw head while the drill was spinning. I repeated this process with each chassis screw and was amazed at the results. This made the screws look like new! 
Meguiar's PLASTX and an old toothbrush work wonders on cleaning up old knobs!
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I use a lot of Meguiar's automotive products when restoring vintage radios. I already have these products on hand for taking care of my cars and motorcycles.
Step 5 Masking and Painting
It is important to remove all wax and grease residue from parts to be painted. Just prior to paint, I wipe down all parts to be painted with Prep-All made by the company Klean-Strip. This clear liquid chemical dries quickly leaving no residue.
The first item to be painted was the metal speaker frame. I carefully masked off the speaker cone to prevent overspray then applied Prep-All to remove wax and grease residue. Painting the metal speaker frame required two paint sessions, allowing 24 hours of drying time between them. One session to paint the mounting tabs on the front of the speaker and another to paint speaker frame on the back. I used Krylon Shortcuts Chrome spray paint on the speaker frame. It is available at most craft stores. Please see my slideshow below for a pictorial view of the steps.
On many parts to be painted, I use magnet wire to suspend them. This allows me to paint all surfaces and then let them hang to dry.
I carefully store painted parts so as to prevent them from being scratched. I placed a paper towel at the bottom of a plastic storage bin then place the parts in it so they are not touching.
I painted the main chassis with Dupli-Color HWP101 Silver High Performance Wheel Paint, this paint is durable and has texture which hides surface imperfections. I carefully masked off all components that I didn't want painted. In addition, I masked off the component side of the chassis. I didn't paint the component side of the chassis because many components are electrically grounded to it, paint is not conductive. As before, I suspended the chassis with magnet wire, allowing me to paint all surfaces and then hanging to dry. Please see my slideshow below for a pictorial view of the steps.
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I typically use Dupli-Color Wheel Paint when painting vintage radio chassis. This paint is durable and has texture which hides surface imperfections.
The brass mounts that hold the carry handle to the Heathkit XR-1L case were badly corroded. First I lightly sand them and then painted them gold. I used a test lead with alligator clip to hold them while they were being painted.
I used a sharp bamboo stick to paint the dial scales on both the Tuning and Power/Volume knobs. I used Acrylic Enamel Gold paint that I have on hand for my model railroad hobby.
Step 6 Chassis Assembly
First, I had to attached all ground lugs, terminal strips, and speaker standoffs with the original screws, nuts, and lock washers. Four of the screws also server double-duty and hold the audio and interface transformers in place. The screws holding these items in place were removed for paint. Next, I had to solder the wires connected to the audio and interface transformers to the proper points on the terminal strips.
The Tuning capacitor needs to be installed to the left side panel first. Then the side panel can be attach to the chassis with three screws. I had to install a solder lug, circled below, as the painted side panel will electrically isolate the frame of this air capacitor from the chassis. Once the side panel is attached to the chassis, I will run a wire from this solder lug to a chassis ground point.
Here is a picture of the chassis with both left and right side panels attached. The Power/Volume control, circled below, was attached to the right side panel after it was attached to the chassis with three screws. In addition, I installed the loopstick antenna to the top of the chassis.
Time to install the ground connection between the Tuning capacitor and the chassis. I circled in red the soldered endpoints for this connection. At this point I also soldered the rest of the connections to the Tuning capacitor and the loopstick antenna, these connections are circled in yellow. Note: There are other connections to the Tuning capacitor and loopstick antenna on the other side of the chassis that are not displayed in the picture below.
The audio transformer's wires are then soldered to the speaker terminals.
The speaker is mounted to standoffs, attached to the chassis, with screws.
I decided to attach a 9 Volt battery clip to the battery terminals. This allows me to power my Heathkit XR-1L radio by either a 9 Volt battery or six D batteries, as originally intended.
I cut a rectangular piece of packing foam that fits the height and depth of the battery compartment. I then cut a rectangular opening in the center just big enough to hold the 9 Volt battery snuggly. Picture below is the 9 Volt battery in its newly constructed holder.
Step 7 Final Testing and Alignment
It is always a good idea to test electronics before buttoning it back up into their enclosure. In addition, I wanted to check the alignment of this radio as it was built from a kit. The Heathkit XR-1L radio can be aligned without any special equipment. Before performing the alignment, I installed the transistors in their appropriate sockets. Here are the alignment steps I used, based on my experience with Superheterodyne radios. It differs slightly from the official Heathkit XR-1L alignment procedure.
Step 8 Install Chassis
The last major step is to install the chassis into its leather case. First, I treated the leather case with Meguiar's Rich Leather Conditioner. I have many Meguiar's automotive products on hand for use on my automobiles.
The original formed leather handle was missing from my Heathkit XR-1L radio, I assume it rotted away many years ago. I found a suitable guitar amp leather carry handle on Amazon that will do nicely. The replacement leather handle matches the cream color of the Tuning and Power/Volume control knobs.
I cut off the original chrome mounts of the replacement leather handle with a Dremel cut-off saw. I then fashioned handle connecting rings using cloth coated wire painted gold. I then soldered the ends of the cloth coated wire together. The soldered ends will be concealed in the brass mounts attached to the leather case.
The brass mounts that connect to the leather carry handle have clips that pass through the leather case. The clips are then bent over to secure them to the case.
Here is a picture of the replacement leather strap installed.
Finally, the chassis can be installed in the case. It is held in place by two screws. I have circled where the screws are installed.
Here is a picture of my newly restored Heathkit XR-1L.
My newly restored Heathkit XR-1L AM Radio in action!
Below are before and after pictures of the chassis of my Viking Messenger 1 CB Radio. I think you'll agree that my rebuild was a complete success!
About the Viking Messenger 1
The Viking Messenger 1 is a radio transceiver, designed by the EF Johnson company, for two-way radio service in the 27Mhz Citizens band. This transceiver was manufactured beginning in 1958 until the early 1960s. In 1961 it went for around 140 dollars retail. The Messenger 1 consists of a crystal controlled Superheterodyne receiver and a crystal controlled two-stage transmitter. The antenna, power supply, and some of the audio circuits are shared between receiver and transmitter functions.
There are five different models, each with different operating voltages. My Messenger 1 is a model 242-128 that can be powered by 12 Volts DC for mobile, or 117 Volts AC for base station use. For 12 Volt DC operation, the Messenger 1 uses a Interrupter or Vibrator relay to pulse the current through a step up transformer in order to achieve the high B+ DC Voltage required for the electron tubes. The Messenger 1 has a complement of ten electron tubes and 2 diodes. Its crystal controlled frequency range is between 26.965 to 27.555 Mhz incremented into five channels. The dimensions of the Messenger 1 are 5 5/8 Inches high, 7 Inches wide and 11 3/8 Inches deep, which is quite bigger than the transistorized CB radios of the 1970s. In addition, it weighs a fairly hefty 12 pounds! Before pictures
The inside of my Messenger 1 was pretty nasty, several of the electron tubes were missing and one was cracked and unusable. I found a petrified hornets nest laying on the top of the chassis. Still, there was promise. You can see towards the bottom where I wiped the chassis with a Windex moistened paper towel. Somewhere under all of this dirt is a working CB transceiver!
Pictured below is the back of my Messenger 1, on the bottom left is the power connector. On the right hand side is the antenna connection. Through the hole you can see the base of the Interrupter relay, used in the high voltage power supply circuit when powered by 12 Volts DC.
Below is a picture of the Messenger 1 microphone with push to talk button. The high impedance ceramic microphone element is housed in a Cycolac resin case.
The EF Johnson Viking emblem, I plan on cleaning it up then applying red paint to the "J" and black paint to the background around the Viking head.
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I consult this book often during radio restoration. I grew up in the transistor and rectifier era and this book taught me a lot about vacuum tube and selium rectifier technology.
Disassembly and Cleaning
The metal chassis is rusted and pitted, no amount of polishing is going to bring it back to its original luster. The only other alternative is to paint it. The grey oblong thing in the upper right-hand corner of the chassis is a petrified hornets nest.
Here is a picture of the bottom of the chassis. The discrete parts (resistors, diodes, transformer, coils) are dirty but in good condition.
Two out of three of the knobs were missing from my Messenger 1, the third had a set screw with a stripped head that had to be drilled out.
The face plate is held onto the chassis by two brackets and the nuts on the shafts of the Volume and Squelch controls.
Circled below are the screws that have to be removed in order to free the faceplate from the chassis.
Contact cleaner was applied to the Channel selector's contacts. I then moved the Channel selector to all five positions in order to clean the contacts. It is best to do this before the chassis is painted as some contact cleaners will harm paint.
I applied Labelle 107 Oil to the base of all the Channel selector switch and the Squelch and Volume control potentiometers. I have this oil on hand due to my model train hobby. This oil will will not harm plastic components.
I apply Labelle 106 Grease to the bearing of the Channel selector switch that provides the "ratchet" action. This grease will not harm plastic parts.
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I use Labelle oil and grease for my radio restoration projects. I already have these products around as I am also a model railroad enthusiast. These products will not harm plastic.
The top and sides of the chassis will need to be wet sanded in preparation for paint. First, I removed all electron tubes from their sockets, then I removed many other parts mounted to the top of the chassis so as to make it easier to wet sand and paint. Parts removed included a multi-section electrolytic capacitor, large electrolytic capacitor, Channel selector switch, indicator lamps and the terminal strip. I left the power, Oscillator, and IF transformers in place as these components have multiple connections making them difficult to remove.
The top and sides of the chassis was then wet sanded and rinsed several time, below is the result.
The metal enclosure is faded and will need to be repainted as well. It got a good scrubbing in dish soap in order to remove the grease and grime, prior to paint prep.
Molex pins were added to the microphone and speaker connections so that it can be easily disconnected if needed.
Molded Capacitor Replacement
Much like paper capacitors, molded capacitors become very unreliable with age and should be replaced with one of similar capacitance and equal or above Voltage rating. Molded paper capacitors are not polarized although they may have a black band on one side indicating which lead is connected to the outside foil. Circled below are the molded capacitors that will be replaced in my Messenger 1.
I replace molded capacitors with new Polypropylene type. Circled in the picture below.
Electrolytic Capacitor Replacement
As electrolytic capacitors age, their electrolyte dries up causing their electrical capacity to drop and leakage current to increase. It is definitely a good idea to replace 50 year old electrolytic capacitors like the ones in the Messenger 1!
Electrolytic capacitors should be replaced with one of similar capacitance and equal or above voltage rating. These type of capacitors are also polarized so make sure you observe the polarity of the capacitor to be replaced and install new the same way. At this point I only replaced electrolytic capacitors contained within the chassis. The multi-section and power supply electrolytic capacitors mounted on top of the chassis will be installed after paint.
Electrolytic Capacitor Kits on Amazon!Restoring the Multi-Section Capacitor
Multi-section capacitors, which are aluminum cans containing several discrete capacitors all connected to a common ground, were popular in the 1960s. There were used mostly in the power supply sections of vintage electronic devices. You can purchase replacement multi-section capacitors but they are expensive. I typically rebuild them by replacing their guts with inexpensive discrete capacitors of the same or slightly greater capacitance and working voltage. The multi-section capacitor in the Messenger 1 is circled in the picture.
The multi-section capacitor in the Messenger 1 contains the following discrete capacitors:
Capacitor A 15uF @ 300Volts Capacitor B 10uF @ 150Volts Capacitor C 10uF @ 25Volts The wiring connected to it's base terminals, circled below, must be desoldered before removing it from the chassis. 
Here is a picture of the multi-section capacitor removed from the chassis. The three solder lugs in the center connect to the positive side of the internal electrolytic capacitors. All internal capacitors share the solder lugs at the rim for their negative connection.
I use wire cutters to uncrimped the bottom of the multi-section capacitor. Then I use needle nose pliers to pull the crimped sections away from the base. This allows me to pull the guts of the multi-section capacitor out of the aluminum can.
The anatomy of a multi-section capacitor. The three internal electrolytic capacitors are rolled up into one assembly.
I was only able to fit the replacement 22uF @ 300 Volts and one 10uf @ 25 Volts electrolytic capacitors inside the aluminum can, the other 10uF @ 150 Volts electrolytic capacitor will be soldered to lugs and concealed within the chassis. Note: The electrolytic capacitor in the picture is only rated 22uF @ 250 Volts. It was replaced with a 22uF @ 300 Volts capacitor after the picture was taken.
I use a Dremel with cutoff tool to remove the area from the base of the multi-section capacitor's aluminum can that I bent with needle-nose pliers.
I then use the Dremel with wire brush tool to remove burrs.
I buffed up the mutli-section capacitor's aluminum can, looks like it did when it was new!
The aluminum can, when glued in place, will conceal the discrete replacement capacitors. You will never know it was refurbished once the aluminum cover is installed! The multi-section capacitor will be installed after the chassis is painted.
Paint and Polish
The power transformer, located toward the rear of the chassis, will be painted first. I lightly sanded the transformer in order to remove any loose paint and rust. Then, I carefully mask off the area around the power transformer. I use a "paint prep" degreaser on the transformer just prior to paint.
I sprayed the power transformer a matte black. Matte works best to conceal surface imperfections.
Time to paint the entire chassis. I carefully masked off the power transformer, tube sockets, and Oscillator and IF transformers. In addition, I applied masking tape on the underside of the chassis to cover many of the open holes so as to reduce the amount of overspray on the internal components.
It is important to choose a paint that will hide imperfections on the surface of the chassis, such as the one from my Messenger 1. I choose Rust Oleum Metallic Paint & Primer in Titanium color. This paint is thicker than the average spray paint, it lays down a "sparkly" finish. Both of these spray paint attributes hide the surface imperfections quite well. See the finished product below:
Rust Oleum Metallic Paint & Primer on Amazon
The metal enclosure was also treated to a fresh coat of paint. I once again used a Rust Oleum Paint & Primer in Hunt Club Green in Satin finish to hide surface imperfections.
The front panel was salvageable and did not require paint. I used Meguire's Metal Polish to bring back the shine.
I think you'll agree that the front panel looks fabulous after polishing.
The final touch was to repaint the logo on the faceplate. I used acrylic enamel paint that I have on hand for my model railroad hobby.
The speaker frame was treated to coat of silver paint, just prior the speaker cone was masked off and the audio transformer was removed.
It was a little more difficult to paint the mounting tabs on the front of the speaker frame. I had to create a masking tape "silo" to prevent overspray on the speaker cone.
Look, no overspray on the speaker's paper cone!
Little parts, such as the Channel selector mounting bracket and the Interrupter socket were also treated to a coat of silver paint after they were properly degreased.
The microphone was disassembled and the Cycolac resin case was buffed to a fine sheen. Meguire's PLASTX works great on Cycolac.
Meguiar's Detailing Products on Amazon
I use a lot automotive detailing products in my radio restorations. I use Meguiar's products as I have them on hand for detailing my cars.
I carefully masked off the Cycolac case around the microphone clip.
The microphone clip was treated to a coat of silver paint, then the microphone was assembled. I used Armor All to bring back the shine in the microphone's coiled cord. The microphone leads were originally soldered to connections in the chassis, I chose to add Molex pins to the connections so that the microphone assembly wiring could be easily disconnected if needed.
Assembly
I use a piece of paper with a hole cut in it the diameter of the nut. I then place it around the nut when tightening in order to prevent the paint from being scuffed.
I also place electrical tape on the end of my crescent wrenches to prevent the paint from being marred while tightening nuts.
The power supply electrolytic capacitor was then installed. The original electrolytic capacitor was rated 80uF @ 450 Volts, I replaced it with one rated 100uF @ 500 Volts
I typically replace screws with rusted or corroded heads, they look terrible against the newly painted chassis. I sometimes repaint the heads of screws, that I cannot easily replace, with silver acrylic enamel paint.
The Channel selector switch and mounting bracket were installed next. A transmit/receive pair of crystals are installed in the white porcelain sockets at the top. The Messenger 1 only has the ability of selecting five CB channels, unlike newer solid state models capable of forty channel selection. In addition, the multi-section capacitor was installed, a dab of hot glue at the base holds the aluminum cover of the multi-section capacitor in place.
The discrete pins for the microphone and speaker connections were installed in Molex connectors. A strain relief was added to keep the microphone's coiled cabled in place.
Finally, the terminal strip and the power indicator neon light was installed. In addition, the "mod" or transmit modulation neon light was also installed. That's all the assembly for the chassis.
I installed new rubber feet on the metal enclosure.
A new microphone clip was installed on the side of the metal enclosure.
Testing
All tubes were tested prior to installation into the Messenger 1 chassis. Any tubes that had a milky white film were not be tested and immediately discarded as the vacuum integrity had been compromised.
The remaining electron tubes were tested with my trusty Eico 635 Tube Tester. Tested "Good" tubes were installed back into the Messenger 1 chassis.
The Interrupter, also known as a Vibrator, is an electromechanical device that "interrupts" the DC (Direct Current) current flow of a low Voltage, in this case 12 Volts. An Interrupter produces AC (Alternating Current) with high Voltage potential when its output is fed into a step-up transformer, like the one used in the Messenger 1. This is high Voltage is rectified into 370 Volts and 200 Volts DC used to provide B+ to the Anodes of the electron tubes in the transceiver. In the Messenger 1, the Interrupter is only used when it is being powered by 12 Volts DC, as in a installation inside of a vehicle. It uses different circuits when powered by household current with a potential of 117 Volts AC.
The Interrupter employs a coil much like in a electromagnet. At this point I only tested to see if the coil was "open". As you can see from my Digital VOM (Volt-Ohm-Meter), the coil in the Interrupter has a resistance of 99.8 Ohms which is the expected resistance of coil. Good news, the Interrupter passed its initial test and will be installed on the Messenger 1 chassis. 
An antenna switching relay is incorporated in the Messenger 1. It is activated when the microphone is keyed, and connects the antenna to the transmitter circuits. By default, when the relay is de-energized, the antenna is connected to the receiver circuits in the transceiver.
I connected a 9 Volt battery to the relay's coil in order to test. The relay contact should pull in when the coil is energized. The antenna relay worked as expected. 
I used ultra-fine sandpaper to clean the antenna relay contacts.
I initially tried to power up my Messenger 1 using 12 Volts DC. This was accomplished by connecting jumpers across pins 1 and 2 and also across pins 5 and 7 on the 9 pin power connector located on the back of the chassis. +12 Volts was applied to pin 6 while the pin 9 was connected to the negative connection of my bench power supply. I figured it was much safer to test when powered by low Voltage then to connect it to high Voltage household current, which is rated at 117 Volts AC. My Messenger 1 did not power up under 12 Volts DC.
After a little investigation, I determined that the Interrupter was not passing current to the power transformer. In order to troubleshoot the problem I needed to disassemble the Interrupter to take a look at its innards. The first step was to uncrimped the bottom of the aluminum can that encloses the Interrupter using wire cutters. 
Upon examination, I determined that that Interrupter's contacts had a black film on them that prevented good electrical contact. I used ultra-fine sandpaper to remove the film and then used my VOM (Volt-Ohm-Meter) to verify continuity.
Once repaired, the Interrupter's relay mechanism was stuffed back into its aluminum can. The relay mechanism is typically contained in a foam rubber sheath in order to reduce noise. Make sure you reinstall the sheath. I then used Super Glue to secure the Bakelite base to the bottom of its aluminum can. Rubber bands were used to hold the base in place while the glue dried.
Electrical tape was used to cover the scratches and gouges made to the Interrupter's aluminum can during the uncrimping and disassembly process.
Finally, the Messenger 1 sprung to life, powered by 12 Volts DC from my bench power supply. Once an antenna was connected, I received atmospheric "hiss" on several channels, on one channel an actual conversation could be heard.
Time to test my Messenger 1 powered by household current. The jumpers on 9 pin power connector need to be configured differently to be powered by 117 Volts AC. Pins 4 and 5 are connected together by jumper, in addition, pins 8 and 9 are also connected together by jumper. 117 Volts AC is applied to pins 3 and 6. Success! Once again my Messenger 1 power up under household current. Do not touch the chassis when initially powered by household current until you determine if household current AC "Hot" should be connected to pin 3 or 6. You will need to flip/flop the AC connections on pins 3 and 6 if 117 Volts AC is measured between the chassis and AC circuit ground. As you can see from VOM meter reading below, AC Voltage between chassis and AC circuit ground dropped from 117 Volts to 5.53 Volts AC once the AC connections were swapped.
Faceplate Install
The faceplate was installed after my Messenger 1 had been throughly tested. The faceplate is attached to the chassis with the nuts on the shafts that hold the Volume and Squelch potentiometers in place. In addition, two brackets attach between each side of the chassis and the right and left upper section of the faceplate.
The metal enclosure slides on from the back. It fits snuggly in place around the front panel. It is important to make sure the microphone cable does not get crimped during the enclosure install process. The metal enclosure is held in place with four sheet metal screws that hold it securely to the chassis.
As mentioned, all but one knob was missing. It was destroyed during the disassembly process as I had to drill out the stripped set screw. I replaced the knobs with black plastic 27mm diameter knobs with set screws, available from Amazon. With that, the rebuild of my Viking Messenger 1 CB Radio Transceiver was complete!
Replacement Knobs on AmazonMy newly refurbished Viking Messenger 1 in action! About the Admiral 7P35N Portable RadioAdmiral 7P35N was a "portable" AM radio, designed an built by the Continental Radio & Television Co. of Chicago, Illinois. This radio qualifies as portable as it can be powered both from Household Current or by battery power. The Admiral 7P35N is a post WW II radio that was first released to the consumer market in 1947. This radio is of Superheterodyne design and covers the standard AM Broadcast Band (540 - 1600 kHz). The Admiral 7P35N is of "transformerless" design, feeding the Household Current though a Selenium rectifier, filter capacitors, and a resistor network in order to provide the 90 Volts DC to the electron tubes. Electron tube filaments are connected in series and are supplied 9 Volts DC. This design makes this radio very dangerous to work on when powered from AC Household Current as the chassis could be connected to "Hot" depending on how the non-polarized plug is connected to a wall outlet. A switch allows you to use an internal battery to power the radio. An internal label specifies the battery of choice is an ENSIGN AB50 which supplied the required 90 and 9 Volts DC needed for operation. Below is the complement of electron tubes installed in the Admiral 7P35N and their purpose: 1U4 = RF Amplifier 1R5 = Mixer/Oscillator 1U4 = IF Amplifier 1S5 = Detector/Preamp 3V4 = Audio Amplifier The Admiral 7P35N comes in a smart looking leather case with a Bakelite handle. A protective flap covers the tuning and volume knobs, speaker grill, and tuning dial when not in use.  Access to electron tubes and battery compartment is achieved through a hinged back cover.  A label on the inside of the hinged back cover indicates chassis layout with electron tube positions, suitable household currents, and a chart of compatible replacement batteries. An interesting feature of this and many radios from the 1940s is that if could be powered from both DC or AC household current as both were available in the United States at the time. DC household current was eventually entirely replaced by AC.  About the Continental Radio & Television CompanyRoss Siragusa founded the Continental Radio and Television Corporation in Chicago during 1934. Admiral Corporation was a subsidiary of Continental Radio and Television Corporation of which consumer electronics were marketed. In addition to the Admiral name, Continental Radio and Television Corporation marketed their products under the Globe Trotter, Radiomaster, and Star Raider names. During WW II, electronic equipment was supplied to the military under the Admiral brand. Admiral branded televisions were a top seller during the "Golden age of Television", which spanned from 1947 to 1960. Successful television sales allowed the company to branch out into large appliances, such as washers and refrigerators, in the 1950s. Admiral Corp was also successful in moving product through major sales outlets such as Montgomery Ward and Sears. In 1960, its heyday, Admiral Corporation boasted sales of 300 million and employed 8,500 people with four manufacturing plants. Like many American consumer electronic companies in the early 1970s, Admiral Corporation hit hard times due to electronics dumped on the US market from Japan. Rockwell Automation purchased the company in 1973, they proceeded to sell off large appliance manufacturing operations to Magic Chef. This division was later sold to Maytag and finally to Whirlpool. Whirlpool now markets the Admiral brand exclusively through The Home Depot chain. In the 1990s Admiral branding was being used on Zenith products. Currently television business continues under AOC (Admiral Overseas Corporation) International that sells LCD and HDTV appliances. The Admiral name lives on, but is used to rebadge large appliance and consumer electronics manufactured by other corporations. ConclusionPlease stop by radioboatanchor.com in the upcoming months to see updates on the restoration of my newly acquired Admiral 7P35N Portable Radio.
The Story
I love to frequent rummage sales during the winter and garage sales during the summer, looking for vintage radios to restore and add to my collection. I happened across this GE 10-Band Portable Radio in the "Free" bin on the last day of a local rummage sale and decided to give this radio a good home.
This GE 10-Band Radio had many issues upon initial inspection:
- The metal tuning dial scale broke free and was just sitting behind the tuning dial window. - The Band Select and UHF Faceplates also broke free and were sitting inside the tuning dial window. - The metal Memory Log scale came unglued from the cabinet front. - All of the screws holding the back cover were missing, it was just snapped in place. - The antenna tip was snapped off. - The original volume knob was missing, the orginal plastic knob was replace with a brushed aluminum one. - The silver paint around the tuning dial window that was once was emblazoned with the GE logo was completely worn off. - The vinyl cladding on the AC electric cord has become so brittle with age that I was unable to unravel it from case in the battery compartment. Despite all of its issues, I knew that this radio could be successfully restored. About this Radio
The General Electric Model 7-2971A 10-Band Portable Radio was a multi-band analog radio offered to consumers starting in 1975. Through research, I discovered that it was still for sale in 1979 as it was advertised in a Popular Mechanics magazine of that year. The price of this radio in 1975 was $120, or about $500 today adjusted for inflation. This radio was of the standard Super-Heterodyne design and covered the following bands:
AM Broadcast 540 - 1600 kHz FM Broadcast 88 - 108 MHz CB: Ch 1- 40 (27 MHz), UHF: 448 - 512 MHz, SW1: 11.8 - 21.9 MHz, SW2: 5.1 - 9.9 MHz, PS-LO: 30 - 50 MHz, PS HI: 150 - 174 MHz Air: 108 - 136 MHz, Weather: 162.40 - 162.55 MHz. This radio has a separate tuning control and dial indicator for UHF. Weather station tuning is done blindly with a thumbwheel located on the back cover. Pushbuttons on top of the radio control access to UHF, CB and Weather bands. The General Electric Model 7-2971A incorporates three antennas, an internal loopstick and groundplane antenna. In addition, it has an external telescopic whip antenna. Being portable, it could be powered by either 120 Volts AC household current or six D cells. Back Cover Removal
Access to the internal electronics of General Electric Model 7-2971A is done by removing the back cover. You must remove five screws (circled in red) on the back cover and one inside the battery compartment. As mentioned, all of the back cover screws were missing from my radio. Be careful when removing back cover as there are two wires that connect the battery compartment to the printed circuit board.
The craftsmanship of consumer electronics from the 1970s leaves much to be desired, parts are haphazardly installed in the single sided printed circuit board, jumper wires everywhere. The parts in the RF section are covered in wax, I assume to prevent vibration oscillations to occur when the radio is transported or set down.
Printed Circuit Board Removal
The printed circuit board will need to be removed, in order to fix the tuning dial scale, Band Select and UHF faceplates that have broken free.
The first step to printed circuit board removal is to remove the Tuning, UHF Tuning, and Volume knobs. They are of "push on" type and can be pulled off just as easily.
You will also need to remove the Band Switch knob, it is also of the "push on" variety and can be pulled off easily.
Don't forget to remove the Squelch knob located on the top of the radio.
The leads of the power transformer are soldered to the printed circuit board. The power transformer will need to be removed with the printed circuit board. You will need remove the screws, circled below, in order to free it.
In addition, you will need to remove the screw circled below to free the AC Power Cord that connects to the primary winding of the power transformer.
Desolder the connections to the speaker and external antenna. Locations are circled in the picture below.
Time to remove the screws holding the printed circuit board in place. I circled their locations in the picture using magenta so that you could see it against the red printed circuit board. Check carefully, there may be screw locations that I missed as some of the screws holding the printed circuit board in place were missing.
There is a control panel mounted inside the top of the cabinet. Attached to it is a Headphone jack, and controls for Squelch, Bass, Treble. The jack and controls on the control panel are hard wired to the printed circuit board. In order to access the control panel, you will need to flip the main printed circuit board 180 degrees towards the top of the radio cabinet. Circled below are the locations of the screws holding the control panel in place.
Finally, the printed circuit board, power transformer, and control panel can be removed from the cabinet.
Fixing the Tuning Dial Scale and Faceplates
As mentioned, the main tuning dial scale came unglued at some point. I used E6000 Industrial Adhesive to glue the main tuning dial scale back onto its mount.
The Memory Log scale also came unglued.
The Memory Log scale proved challenging to fix. First, I had to completely remove it then scrape all of the remaining glue from the underlying mating surface. In addition, I had to straighten and flatten the Memory Log scale then lightly sand the back of it to remove all of the old adhesive.
I then applied a bead of Super Glue to the back of the Memory Log scale then pressed and held it in place for several minutes until the glue set.
The Band Select and UHF Faceplate also came unglued. They were located in the areas circled below.
Gluing the Band Select and UHF Faceplate was a little more tricky. I had to apply E6000 Industrial Adhesive to the back of the faceplates then maneuvered them in place from behind the main tuning dial window. I then used a screwdriver to press them in place.
Volume Control Repair
A previous owner replaced the Volume Control potentiometer but did a lousy soldering job on the connections. Below is a picture after I desoldered the connections, stripped the wires, then re-soldered connections to the potentiometer.
Antenna Repair
As with many older radios, the end cap had broken off of the external antenna.
Finding a direct replacement antenna for vintage radios can be challenging.
I replace missing antenna end caps with pieces from my daughter's LEGO set. Don't worry, she won't miss the few pieces I appropriate as she has many more. Gluing the LEGO piece to the end of the antenna will not provide enough tensile strength and it will eventually come off. I drill a small hole through the antenna end and LEGO piece then drive a small terminal pin through it. I then cut the ends of the terminal pin flush with the LEGO piece and add a dab of Superglue at entrance and exit holes to keep it from coming out. 
Power Cord
The vinyl cladding on the original power cord had grown stiff and brittle with age. I cut the power cord off to make handling the printed circuit board easier. It will be replaced during reassembly.
Electrolytic Capacitor Replacement
As electrolytic capacitors age, their electrolyte dries up causing their electrical capacity to drop and leakage current to increase. As a rule, I typically replace electrolytic capacitors in vintage electronic equipment. Electrolytic capacitor replacement will prove difficult on this radio, as you will have to remove the tuning dial mount and dial cords, in order to gain access to the foil side of the printed circuit board. In addition, stringing the two dial cords during reassembly would prove a nightmare.
I decided against replacing electrolytic capacitors in the General Electric Model 7-2971A. Through bench testing I determined that the electronics of this radio worked perfectly without electrolytic capacitor replacement. There was no tell-tale hum of failing filter capacitors when powered by AC house current. It worked perfectly under battery power as well.
Lubrication
I use Labelle 107 oil to lubricate all of the pulleys for the tuning dial indicators. This oil is safe for plastics. I have this oil on hand for my model train hobby.
I use Labelle 106 Grease to lubricate the gears for the Band Select indicator.
Cabinet Detailing
With the electronics removed, I took the opportunity to detail the cabinet of this radio. I use many car care products for cabinet detailing. Meguiar's PLASTX works great for removing fine scratches from the tuning dial window.
Armor All Protectant works great for cleaning and shining the cabinet and back cover. I used the Advance AutoParts equivalent of Armor All.
The felt filter over the vents in the back cover had disintegrated due to age. I replaced with a rectangular piece of Speaker Grill Cloth.
The silver paint around the tuning dial window had completely worn off. I carefully masked the area off with Frog Tape then wiped the area to be painted with denatured alcohol to remove any grease residue.
I sprayed the area with three coats of silver paint giving time to dry between coats to avoid runs or sags.
Here is the finished product. My only regret is that I had no way of stenciling the GE logo that used be in the lower left corner of the silver painted area.
I also use Meguiar's PLASTX and an old toothbrush to clean up buttons and knobs.
Reassembly
Reassembly is the reverse process of disassembly, you must first attach the control panel mounted inside the top of the cabinet before installing the printed circuit board. Make sure you reinstall the push buttons at the top of the printed circuit board before installation, if you took them off for cleaning.
Make sure you solder the yellow and orange wires to the speaker. In addition, a small polyester capacitor is connected between the speaker terminal with the yellow wire and the main tuning capacitor.
I replaced the power cord with non-polarized one I cut off of a broken Soldering Iron. I stripped the transformer and power cord leads then soldered them together.
I then used heat-shrink tubing to cover and insulate the soldered connections.
Solder the white antenna wire to the solder lug located at the base of the external antenna.
One screw at the base of the antenna holds it in place.
Two screws hold the power transformer in place.
The power cord is channeled through cavity on the inside of the cabinet that provides strain relief. It is topped with a piece of insulating fish paper that is held in place with a single screw.
Green and black wires from the printed circuit board connect to the battery compartment, built into the back cover. The green wire goes to the positive terminal and the black wire goes to the negative terminal of the battery compartment. I extended these wires, allowing me to sit the back cover flat beneath the radio cabinet.
Install all of the knobs on radio. All of the knobs are keyed so you can't a mistake when installing them. As mentioned, a lot of the original screws for this radio were missing. I had to search my junk box for suitable replacements.
You will need to thread the power cord through the hole in the battery compartment of the back cover. Carefully install the back cover on the cabinet, making sure you don't crimp any wires where they mate. Six screws hold the back cover in place. One screw hole is located in the battery compartment.
Make sure you attach the pointers on the Memory Log. Also install the battery compartment cover.
Below is a picture of the finished product!
My recently restored General Electric Model 7-2971A 10-Band Portable Radio in action!
Here is a before and after picture of my vintage Zenith Consoltone Model 5D011Z Radio. I think you'll agree that the makeover was a complete success!
About my Zenith Consoltone radio
I paid $12 plus shipping for this radio at on online auction. I don't think any other "vintage radio enthusiast" wanted to touch it because:
1. There was physical damage to the Bakelite cabinet: 
2. The end of the shaft of the combination Tuning/Volume/Power control was sheared off (circled in red below). This is a specialized potentiometer/switch and will hard to find an exact replacement.
3.The power switch knob was missing. Most collectors know how hard it is to find matching knobs.
4. The cardboard back panel was in rough shape. 
"Old Time Radios! Restoration and Repair" book on Amazon
I consult this book often during radio restoration. I grew up in the transistor and diode era and this book taught me a lot about vacuum tube and selium rectifier technology.
Step 1 Remove Chassis from Cabinet
The Zenith Consoltone uses only two screws to hold the chassis in the cabinet. One on each side of the chassis. The tuning knob must be removed first. It just pulls off. As mentioned, this radio is missing the Power/Volume control knob. Once the screws and knobs are removed, the chassis slides straight out of the back of the cabinet.
The tuning dial window and speaker grill are held in place with what I call "compression rivets", four each (circled in the picture below). You simply use a small screwdriver to pry them out from under the head of each rivet.
Handle the tuning dial window with care as it is made from some brittle predecessor to plastic and can easily crack. I removed both the tuning dial window and speaker grill to clean them and to prep the cabinet for repair and paint. 
Step 2 Chassis Cleaning and Lubrication
I removed the internal spider web antenna and antenna bracket from the radio chassis. You must desolder the two antenna connections from the tuning capacitor before it is free and clear. Removing the antenna and antenna bracket made handling the chassis during the cleaning and repair easier.
I use compressed air to remove any loose dirt, then Windex moistened paper towels to remove any remaining dirt and grime from the top of the chassis.
Windex moistened Q-Tips work great for getting into hard to reach areas. I only clean the tops of the vacuum tubes as I don't want to remove the markings from the sides of them.
I use Labelle 107 oil to lubricate all of the pulleys for the tuning dial indicator. This oil is safe for plastics. I have this oil on hand for my model train hobby.
I also use Labelle 107 oil to lubricate the shafts of the vintage combination Tuning/Volume/Power control. 
I use Labelle 106 Grease to lubricate the bearings of the tuning capacitor.
Labelle lubricants on Amazon
I use Labelle oil and grease for my radio restoration projects. I already have these products around as I am also a model railroad enthusiast. These products will not harm plastic.
Step 3 Test Vacuum Tubes
Unlike semiconductor transistors that have a near infinite lifespan, vacuum tubes age and become less efficient. In addition, their filaments burn out rendering them inoperable. It is always a good idea to test all vacuum tubes in a radio you are servicing before doing any more troubleshooting.
In addition, make sure that that the right tube is in the right socket. This will save you troubleshooting time later. Pictured below is my Eico Model 635 Vacuum Tube Tester testing a tube from the Zenith Consoltone. 
Step 4 Electrolytic Capacitor Replacement
As electrolytic capacitors age, their electrolyte dries up causing their electrical capacity to drop and leakage current to increase. It is definitely a good idea to replace 70 year old electrolytic capacitors like the ones in the Zenith Consoltone!
Step 4a - Restoring the Multi-Section Capacitor
Multi-section capacitors, which were aluminum cans containing several discrete capacitors all connected to a common ground, were popular in the 1940s. There were used mostly in the power supply sections of vintage electronic devices. You can purchase replacement multi-section capacitors but they are expensive. I typically rebuild them by replacing their guts with inexpensive discrete capacitors of the same or slightly greater capacitance and working voltage. The multi-section capacitor in the Zenith Consoltone is circled in the picture.
The multi-section capacitor in the Zenith Consoltone contains the following discrete capacitors:
Capacitor A 20uF @ 150Volts Capacitor B 20uF @ 150Volts Capacitor C 40uF @ 150Volts The components connected to it's base terminals, circled below, must be desoldered before removing it from the chassis. 
Here is a picture of the multi-section capacitor removed from the chassis. The three solder lugs in the center connect to the positive side of the internal electrolytic capacitors. All internal capacitors share a forth common solder lug at the rim for their negative connection.
I use wire cutters to uncrimped the bottom of the multi-section capacitor. Then I use needle nose pliers to pull the crimped sections away from the base. This allows me to pull the guts of the multi-section capacitor out of the aluminum can.
The anatomy of a multi-section capacitor. The three internal electrolytic capacitors are rolled up into one assembly.
I was only able to fit the replacement 47uF electrolytic capacitor inside the aluminum can, the other two 22uF electrolytic capacitors will be soldered to solder lugs and concealed in the chassis.
The aluminum can, when glued in place, will conceal the replacement capacitor. 
Pictured below is the refurbished multi-section capacitor installed back into the chassis. You will never know it was refurbished once the aluminum cover is installed!
I use a Dremel with cutoff tool to remove the area from the base of the multi-section capacitor's aluminum can that I bent with needle-nose pliers. I then use the Dremel with wire brush tool to remove burrs.
I spray the external cardboard wrapper of the multi-section capacitor's aluminum can with some flat black paint to make it look as good as new.
Hot glue holds the aluminum cover in place over the multi-section capacitor's base.
Step 5 Replacing Paper Capacitors
Paper capacitors, like the ones circled below, become very unreliable with age and should be replaced with one of similar capacitance and equal or above voltage rating. Molded paper capacitors are not polarized although they may have a black band on one side indicating which lead is connected to the outside foil.
I replace paper capacitors with new Polypropylene type. Circled in the picture below.
Step 6 Combination Control Repair
The Zenith Consoltone uses one control that incorporates Tuning, Volume, and Power functions.
As mentioned, the part of the shaft that controls Volume and Power had sheered off. This is a rare part and it will have to be repaired instead of replaced. 
I needed to somehow extend the end of the shaft so that it could accommodate a knob. The first thing a did was drill a small hole at about 3/8 depth. I then inserted a copper pin and soldered it to the brass shaft. This would give my shaft extension some mechanical strength.
I then soldered the base of a crimp lug to both the copper pin and to part of the exposed shaft.
Finally, I cut a slit in the plastic insulator of the plastic lug then super glued it in place on the shaft. This will give the shaft extension the proper diameter for the knob to fit snuggly in place. The slit will allow the set screw of the knob to contact metal giving it a secure hold.
Step 7 IF Transformer Resistance Checks
Circled below are the two IF (Intermediate Frequency) transformers used in the Zenith Consoltone.
As part of my restoration steps, I perform resistance checks using my Multimeter on the primary and secondary windings of all IF transformers. This can be done with the IF Transformer still wired into the radio circuit. The resistance accross the primary or secondary windings should be 50 Ohms or less. I repair the Transformer if I notice that the a winding has an open. Click on the link button below to see my blog on how I repair them.
Step 8 Pilot Lamp Replacement
It is important that you have a working pilot lamp. The Zenith Consoltone requires #47 Lamp. A failed pilot lamp could cause premature failure of the 35Z5GT Rectifier Tube.
Step 9 Initial Testing and Polarized Plug Install
Time to install the vacuum tubes and do initial testing. But before I start testing I install a polarized plug on the end of the power cord. An 120 Volt AC line voltage potential can be on the metal chassis, which can pose an electrocution risk, depending on how the non-polarized AC cord plug is plugged into the power outlet.
I replaced the plug with a polarized one that most closely matched the original. The wider blade should connect to the Zenith Consoltone chassis as this is the Neutral connection. The thinner blade connects to Hot.
With the Zenith Consoltone is plugged into an electrical socket, you should detect only a very low voltage (less than one Volt) AC between the ground connection on the wall socket and the chassis. I used test leads with alligator clips to temporarily connect the spider web antenna.
Success! The Zenith Consoltone immediately picked up a local AM broadcast station once warmed up. 
Step 10 Cabinet Repair
I do not like to apply paint to a Bakelite cabinet as I feel it covers its natural beauty, but I feel I didn't have a choice in the matter due to the large jagged crack, with small pieces missing, on the side.
Click on the link button below to see my blog on Bakelite Cabinet Repair.
Below is a picture of the newly repaired Zenith Consoltone Cabinet
As finishing touch, I spray the paint that I used on the radio cabinet into the lid. I then use a fine paint brush dripped in the paint and apply it along the back edge.
I used a sharp stick dipped in gold enamel to paint the Consoltone logo on the front of the cabinet.
I spray painted a knob I found in my junk box the same color as the cabinet, this will be the new Volume/Power control. I once again used sharp stick dipped in gold enamel to paint the position indicator line on the knob.
I use silver enamel paint to brighten up corroded screw heads after they have been lightly sanded.
I decided to paint the spider web antenna assembly a matt black as this is what you will see from the back of the radio.
The original back panel was too badly damaged to repair. It will not be installed on my restored Zenith Consoltone.
Meguiar's PLASTX works great for restoring old tuning dial windows.
I then use Meguiar's Quik Glass for a streak free shine on the tuning dial window.
Meguiar's Product on Amazon
Meguiar's Automotive Wax and Cleaning products work great for detailing vintage radios!
The original gold speaker grill cloth looked pretty shabby. I replaced it with a new black speaker grill material I had lying around.
Step 11 Assembly
The first step in the assembly process is to install the red pilot lamp lens. A couple dabs of Superglue hold it in place.
The next step in the assembly process is to reinstall the tuning dial window. Four compression rivets hold it in place. I had to install washers under the compression rivets as the tuning dial window had shrunk over the years.
Four compression rivets also hold the speaker grill in place.
The spider web antenna needs to be reattached to the chassis before it can be installed in the cabinet.
It is held in place with one metal bracket. The two wires from the antenna connect to terminals on the tuning capacitor. 
There is one wire on the external side of the antenna that connects to the metal bracket.
Then the chassis is carefully slid into the back of the cabinet. It is held in place by two screws, one on each side of the chassis.
At this point I install the knobs, I install the outer tuning knob first. Then, I install the inner Volume/Power knob. The set screw must be positioned so that it comes in contact with the metal shaft and not the blue plastic spacer I created.
Finally, a picture of the finished product!
Conclusion
I spent many hours restoring this vintage Zenith Consoltone. It was satisfying bringing it back to life. Watch my video below to see my newly restored radio in action.
The Accident
I had built a Doerle Shortwave Receiver that employed two vintage Type 30 vacuum tubes. This receiver, and its pristine Emerson Type 30 vacuum tubes, was the crown jewel of my "home-brew" radio collection. I proudly displayed it, with the rest of my home-brew radio collection, in a shelving unit in my basement. One fateful evening I came downstairs and discovered that the shelf above it gave way, smashing the the two Type 30 vacuum tubes in my Doerle Shortwave. This receiver was of open breadboard design and didn't have an enclosure around it that would protect the vacuum tubes from physical damage.
Type 30 vacuum tubes are relatively expensive, typically between $15 and $20 a piece on most websites, catering to "Tube Amp" enthusiasts. You could also try your luck on an auction site like eBay. I wanted to make my Doerle Shortwave Receiver operational again, but didn't want to drop between $30 to $40 to make it happen! Pictured below is my Doerle Shortwave Receiver, before the accident. 
"Old Time Radios! Restoration and Repair" book on Amazon
I consult this book often during radio restoration. I grew up in the transistor, diode, and integrated circuit era and this book taught me a lot about vacuum tube and selium rectifier technology.
The Idea
Like most antique radio enthusiasts, a have a cache of vacuum tubes and other miscellaneous vintage parts. For some reason I had acquired an unusually large number of 1T4 miniature vacuum tubes. Then an idea formed. Create a tube base adapter that would allow me to substitute a 1T4 for a Type 30 vacuum tube. I liked this idea as it allowed me to get my Doerle Shortwave Receiver up and running at very little cost and without modification. This also allows me to convert back to the Type 30 vacuum tubes should I come across an inexpensive set.
Challenges
Here are the design challenges and specifications I set for the Type 30 to 1T4 Vacuum Tube Converter project:
Design
Vacuum Tube Parts on Amazon
Sparked by the interest of Audiophiles in vacuum tube amplifiers, Amazon offers a wide variety of vacuum tube parts and accessories.
Construction
I bent two solder lugs at right angles, then soldered them to a 7 pin miniature tube socket. This will hold the tube socket to the 4 pin tube base. Sorry about the blurry picture.
I drilled then tapped two holes on the opposite sides of the 4 pin tube base. 4-40 screws will hold the 7 pin miniature tube socket to the 4 pin tube base.
Three small holes were drilled into the side of the 4 pin tube base. These holes will be used for the connections to the 50K potentiometer that will adjust the Screen Grid Voltage.
The 50K potentiometer is held to the side of the 4 pin tube base by bending the three leads once mounted. A dab of Superglue under the potentiometer keeps it firmly in place.
I then connect all the wires, the 10 Ohm resistor, and the .05uF capacitor to the 7 pin miniature tube socket. It is much easier to solder with the tube socket out of the 4 pin tube base.
I drilled another hole in the 4 pin tube base then I threaded a test lead with alligator clip through it. This will be used to connect to B+, needed for the screen grid.
The other end of the test lead is connected to an end terminal of the 50K potentiometer.
A black wire is soldered between the other end terminal of the 50K potentiometer and one of the filament pins of the 4 pin tube base. A dab of solder at the end of the hollow tube base pin holds the wire securely in place.
The 4 pin Bakelite tube sockets I had on hand have a built in pin on the side, I will use this as a test point. I soldered a white wire to it.
The white wire from the test point is soldered to the wiper of the 50K potentiometer. A second white wire is soldered to the potentiometer and will eventually connect to pin 3 of the 7 pin miniature tube socket.
Time to wire the 7 pin miniature tube socket to the 4 pin tube base.
Two 4-40 screws, on opposite sides, hold the 7 pin miniature tube socket to the 4 pin tube base.
Here is a side view of one assembled Type 30 to 1T4 Vacuum Tube Converter. Two converters are required for my project.
Here is a top view of an assembled Type 30 to 1T4 Vacuum Tube Converter.
Vacuum Tubes on Amazon
Believe it or not, Amazon sells a variety of vacuum tubes.
Continuity and Resistance Checks
I always like to take continuity and resistance checks with my Multimeter before putting a piece of newly built equipment into production. I want to make sure that I wired it correctly. I built two Type 30 to 1T4 Vacuum Tube Converters, you can see the second one in the background.
Testing
Once the Type 30 to 1T4 Vacuum Tube Converters passed continuity and resistance checks, it was time to put them into a live circuit. You can see them mounted in the white porcelain tube sockets in the picture below. As you can see, the yellow leads from each Type 30 to 1T4 Vacuum Tube Converters are connected by alligator clips to the B+ (90V and 45V) terminals of my Doerle Shortwave Receiver.
The next step was to install the 1T4 vacuum tubes into the Type 30 to 1T4 Vacuum Tube Converters.
Time to power up my Doerle Shortwave Receiver, equipped with the Type 30 to 1T4 Vacuum Tube Converters and 1T4 vacuum tubes installed, to see if they work. The wood cabinet sitting below my Doerle Shortwave Receiver is a "Battery Box". The Battery Box contains Two D batteries, wired in series and tapped, used to provide 1.5 and 3 Volt A+ Filament. In addition, it contains Ten 9 Volt batteries, wired in series and tapped, to provide 22.5, 45, and 90 Volt B+ Anode. The 9 Volt batteries in the Battery Box are getting weak so I had to a connect extra ones externally to achieve the 90 and 45 Volts B+ required for the Doerle Shortwave Receiver.
Success! I could immediately hear atmospheric "hiss", once my Doerle Shortwave Receiver, equipped with Type 30 to 1T4 Vacuum Tube Converters, was powered on and a suitable antenna and ground were connected. I could pickup several AM an CW (Morse Code) transmissions after I fiddled with the Tuner and Regenerative controls. I use a "home-brew" amplifier to amplify the audio output instead of high impedance headphones. My amplifier is housed in the black project case in the the picture below.
Screen Grid Voltage Adjustment
If you recall, each Type 30 to 1T4 Vacuum Tube Converter had a 50K potentiometer installed so that the Screen Grid Voltage could be adjusted for maximum amplification. In order to adjust the Screen Grid Voltage, I tuned my Doerle Shortwave Receiver to a fairly week AM broadcast transmission then adjusted the potentiometer on each converter for maximum station loudness. Measuring the Screen Grid Voltage to ground with my Multimeter, I found the following to be the optimal Voltages:
Type 30 to 1T4 Vacuum Tube Converter used in the RF (Radio Frequency) Section: 37.5 Volts Type 30 to 1T4 Vacuum Tube Converter used in the (Audio Frequency) Section: 45.6 Volts Conclusion
My fabricated Type 30 to 1T4 Vacuum Tube Converters were a complete success, making my Doerle Shortwave Receiver once again operational. I had all the parts on hand so there was no expense. The best part is that at any time I can remove the Type 30 to 1T4 Vacuum Tube Converters an replace with an actual Type 30 vacuum tubes.
Here is a before and after picture of my vintage RCA Victor 15X Radio. I think you'll agree that the makeover was a complete success!
About my RCA Victor 15X Radio
I paid $10 plus shipping for this radio at on online auction. I don't think any other "vintage radio enthusiast" wanted to touch it because:
1. There was physical damage to the Bakelite cabinet: 
2. The tone switch knob was missing. Most collectors know how hard it is to find matching knobs.
3. The dial indicator, circular and unique to this radio, was missing. 4. The dial cord was either broken or missing. 5. The back panel was missing, exposing the built in antenna. "Old Time Radios! Restoration and Repair" book on Amazon
I consult this book often during radio restoration. I grew up in the transistor and rectifier era and this book taught me a lot about vacuum tube and selium rectifier technology.
Step 1 Remove Chassis from Cabinet
The RCA Victor 15X uses only two screws to hold the chassis in the cabinet. One on each side of the chassis. The Volume, Tone, and Tuning knobs must be removed first. They just pull off. As mentioned, my RCA Victor 15X is missing the Tone switch knob. Once the screws are removed, the chassis slides straight out of the back of the cabinet.
The Tuning Dial Window is also held in place by two screws, one on each side. You can remove the Tuning Dial Window from the back once the screws are removed. Handle the Tuning Dial Window with care as it is made of glass. I removed the Tuning Dial Window both to clean it and to prep the cabinet for paint.
Step 2 Chassis Cleaning and Lubrication
I use compressed air to remove any loose dirt, then Windex moistened paper towels to remove any remaining dirt and grime from the top of the chassis. Windex moistened Q-Tips work great for getting into hard to reach areas. I only clean the tops of the vacuum tubes as I don't want to remove the markings from the sides of them.
I use Labelle 107 oil to lubricate all of the pulleys for the tuning dial indicator. This oil is safe for plastics. I have this oil on hand for my model train hobby.
I also use Labelle 107 oil to lubricate the shafts of the vintage Volume potentiometer and Tone switch.
I use Labelle 106 Grease to lubricate the bearings of the Tuning capacitor. The red arrows indicate the location of the bearings.
Contact cleaner is used on all electrical contacts, like where the potentiometer wiper contacts the resistive element in the Volume control. I then rotate the Volume control back and forth several times.
Labelle lubricants on Amazon
I use Labelle oil and grease for my radio restoration projects. I already have these products around as I am also a model railroad enthusiast. These products will not harm plastic.
Step 3 Test Vacuum Tubes
Unlike semiconductor transistors that have a near infinite lifespan, vacuum tubes age and become less efficient. In addition, their filaments burn out rendering them inoperable. It is always a good idea to test all vacuum tubes in a radio you are servicing before doing any more troubleshooting.
In addition, make sure that that the right tube is in the right socket. This will save you troubleshooting time later. Pictured below is my Eico Model 635 Vacuum Tube Tester testing a tube from the RCA Victor 15X radio: 
Step 4 Rewiring and Capacitor Replacement
As electrolytic capacitors age, their electrolyte dries up, causing their electrical capacity to drop and leakage current to increase. Circled below is one of two electrolytic capacitors used in this radio.
Electrolytic capacitors should be replaced with one of similar capacitance and equal or above voltage rating. It is definitely a good idea to replace all electrolytic capacitors in a 74 year radio, such as this RCA Victor 15X. 
Molded paper capacitors, like the one circled below, become very unreliable with age and should be replaced with one of similar capacitance and equal or above voltage rating. Molded paper capacitors are not polarized although they may have a black band on one side indicating which lead is connected to the outside foil. I replace molded paper capacitors with new Polypropylene type.
The chassis wiring was complete mess in this radio. Some components weren't even soldered in place!
At some point the electrolytic capacitors were replaced. Their leads were just twisted to a wire and covered in electrical tape. Some component leads were twisted around tube sockets pins. It looks like several "novice" repairmen tried to fix this radio with little success. See the carnage below: 
I couldn't trust any of the wiring in the chassis of this radio. I double checked and corrected all wiring during the process of replacing electrolytic and molded paper capacitors. I am rather pleased with the results. See the picture below:
Step 5 Trimmer Cap Replacement
There are two compression-type trimmer capacitors built into the Multi-section Tuning Capacitor. They are adjusted by screws, circled below. The top screw adjusts the LO (Local Oscillator) Frequency, the bottom screw is the Antenna Trimmer. The screw holes were badly stripped out an neither setting could be properly adjusted.
I replaced the built in trimmer caps with two external trimmers of the of same capacitance range (3 to 25pf) See new trimmer capacitors circled below:
Step 6 Tone Switch Repair
The RCA Victor 15X incorporated a Tone on/off switch instead of a potentiometer. The wiper contact of the switch was missing.
I fashioned a new wiper contact out of a spade lug soldered to the end of the shaft. I also drilled small holes and installed a terminal pin, bent into a U-shape, to limit the travel of the switch. The U-shaped terminal pin was held in place by a dab of Superglue. The red arrow is pointing to the travel stop in the below picture.
Finally, I painted my repair with silver enamel hobby paint to make it less noticeable. I did not paint where electrical contact is made.
Step 7 IF Transformer Resistance Checks
Circled below is one of two IF (Intermediate Frequency) transformers used in the RCA Victor 15X.
As part of my restoration steps, I perform resistance checks using my Multimeter on the primary and secondary windings of all IF transformers. This can be done with the IF Transformer still wired into the radio circuit. The resistance accross the primary or secondary windings should be 50 Ohms or less. I noticed that the a winding of the 2nd IF Transformer had an open. Click on the link button below to see my blog on how I repaired it.
Step 8 Dealing with Chassis Rust
My RCA Victor 15X radio had a fair amount of rust on the chassis.
The first step to chassis rust repair is to give yourself some room to work. I removed the vacuum tubes in the near proximity. I also to unsoldered the wires that connects to the pilot light and then pulled the wires through the feed-through hole.
I started with a Dremel with a grinding wheel installed to remove as much of rust as possible. I then sanded the rusted area starting with coarse sandpaper finally finishing with a fine sandpaper.
It is important to perform paint prep before applying spray paint. I masked off the area to be painted. I used denatured alcohol to degrease the area before paint.
I use silver Dupli-Color automotive rim paint as it is the closet color I can find that matches the natural color of most chassis. Apply in light coats and feather it out so as to make a natural transition from the newly painted area to the chassis color.
Repair job complete! Time to install a new grommet in the hole then thread the pilot lamp wires through the grommet and solder to the proper rectifier tube socket terminals. The final step is to install the vacuum tubes into their respective sockets.
Duplicolor Rim Paint on Amazon
I use this paint to touch up places on the chassis that have rusted.
Step 9 Tuning Dial Back Plate Refinishing
The Tuning Dial Backplate, circled in the picture below, was in need of refinishing.
I removed the Tuning Dial Backplate assembly from the chassis and then sanded the area to be painted with a fine grit sandpaper. I then masked off the area to be painted and wiped it down with de-natured alcohol to remove any residual grease.
The next steps were to apply automotive primer and then lightly wet sand, once the primer is dry.
Finally, a leather brown top coat was applied. Once dry, the Tuning Dial Backplate assembly was re-attached to the Chassis.
Step 10 Dial Cord Replacement
The Dial Cord, Tension Spring, and Dial Pointer were missing from my RCA Victor 15X Radio. I fashioned a new Dial Pointer from a Terminal Pin and Solder Lug I found in my junk box.
I painted the newly fashioned pointer red using Enamel hobby paint.
Most radio schematics include a diagram on how to string the Dial Cord.
I used a spring from a battery holder as the Tension Spring.
Finally, the Dial Cord replacement is complete. I will not attach the Dial Pointer to the Dial Cord until reassembly, so that I can properly align it in the Tuning Dial Window.
Step 11 Cabinet Repair
I do not like to apply paint to a Bakelite cabinet as I feel it covers its natural beauty, but feel I didn't have a choice in the matter due to the large jagged crack, with small pieces missing, on the side.
Click on the link button below to see my blog on Bakelite Cabinet Repair.
Below is a picture of the newly repaired RCA Victor 15X Cabinet.
As finishing touch, I spray the paint that I used on the radio cabinet into the lid. I then use a fine paint brush dripped in the paint and apply it along the back edge.
Step 12 Assembly
The first step in the assembly process is to reinstall the Tuning Dial Window. A screw on each side holds it in place.
Then the chassis is carefully slid into the back of the cabinet. It is held in place by two screws, one on each side of the chassis.
At this point I install the knobs, then I rotate the Tuning knob counter-clockwise until I see that the Tuning Capacitor's plates are fully meshed. The next step is to move the Dial Pointer along the top of the Dial Backplate until it shows the lowest point on the Tuning Dial Window. I then affix the Dial Pointer to the Dial Cord with a dab of Superglue.
Next, its time to consult the schematic and solder the wires to the built in antenna. There are also two connections that go to an RCA Jack that allow you to use the radio as an audio amplifier.
The internal antenna is attached to the Chassis with two screws, circled below. I sprayed painted the fiberboard piece that the internal antenna attaches to a matt black.
Finally, a picture of the finished product! I still need to find a replacement knob for the Tone control.
Conclusion
I spent many hours restoring this vintage RCA Victor 15X Radio. It was satisfying bringing it back to life. Watch the video below to see my newly restored radio in action.
My Baofeng UV-3R+ Dual Band UHF/VHF Transceiver has served me well during the year of ownership.
I use mainly the 2M band fucntion in order to communiate with other Amatuer Radio Enthusiests on a local repeater. One day I went to charge my UV-3R+ and noticed that the LED (Light Emitting Diode) on the Charger Base did not rapidily flash between red and green when plugged in. The LED on the Charger Base was off yet the LED on the AC Adapter was lit. In addition, the LED on the Charger Base did not change to a solid red indicating that the UV-3R+ installed was charging. This led me to believe the issue was with the Charger Base itself. Step 1 Disassembly
The bottom of the UV-3R+ Charger Base just snaps in place with the top. All you need to do is take a Jewel's screwdriver and pry where the two halves meet to separate. Do not be fooled by the screw heads on the Charger Base bottom, they are molded in the plastic and serve no purpose.
The next step is to remove the screw that holds the Charger Base printed circuit board in place. See area circled in the picture below.
What puzzles me is the center terminal, circled below, does not have any internal connection. Yet, there is a mating contact on the back of the UV-3R+ battery. Looking on the Internet I have found references of the a "third pin" used to monitor the internal temperature of a Lithium ION battery or to balance a charge between cells. There is the letter "T" over the center contact of the UV-3R+ battery, making me believe this was for a temperature sensor. It is a mystery why this function was never implemented.
Step 2 Diagnosing the problem
I could measure 5 Volts with my Multimeter on the coax male connector that plugs into the Charger Base. It was a mystery why the Charger Base was not being powered. Upon further investigation, I determine that the coax female connector, soldered to the Charger Base printed circuit board, was the culplit. I removed the coax female connector from the Charger Base printed circuit board in order to take a closer look at it.
I immediatley determined the issue once I looked down the barrel of the coax female connector. The center pin had broken free and was pushed back in the connector. This prevented it from making contact with the center contact of the coax male connector. See below picture. 
Step 3 Fixing the Problem
The lead that holds the center pin of the female coax connector was very flimsy. I soldered a much thinker terminal pin to it. This will give it added physical strength that will prevent it from being pushed back into the connector in the future.
I had to drill an extra hole in the printed circuit board in order to accommodate the supporting thicker terminal pin. You can see the end of the terminal pin protruding from the printed circuit board, circled below. This is before I cut the terminal pin flush with the printed circuit board.
Step 5 Reassembly
Putting the charger back together is just the opposite of taking it apart. The printed circuit board is attached to the top section of the Charger Base with a single screw (circled below). The bottom of the Charger Base just snaps in place with the top.
Step 6 Testing
Testing is pretty straight forward, plug the AC Adapter into the wall and connect the AC Adapter cable to the Charger Base. The LED on the Charger Base should rapidly flash between red and green. See area circled in the picture below.
Install the UV-3R+ into the Charger Base, the LED should change to a constant red when charging. The Charge Base LED will change to a constant green once the UV-3R+ is fully charged.
The LED on the AC Adapter is green when:
- It is not connected to the Charger Base - It is connected to the Charger Base and without the UV-3R+ installed. - It is connected to the Charger Base with the UV-3R+ installed and fully charged. The LED on the AC Adapter is red when the UV-3R+ is installed on the Charger Base and it is charging. 
Conclusion
Repairing a UV-3R+ Charger Base is a pretty simple task, requiring a minimum of tools. I recommend disassembling a broken UV-3R+ Charger Base, determine the root failure, and fixing it, before purchasing a new one.
My Inspiration
I came across this great book from 1938 on how to build four different short wave receivers. What was even cooler is that someone took the time to format it in Kindle EBook format! One click and a Kindle version of the vintage "HOW TO BUILD 4 DOERLE SHORT WAVE SETS" book was mine!
"HOW TO BUILD 4 DOERLE SHORT WAVE SETS" Kindle book on Amazon!What is a Doerle Short Wave Set?
Doerle "sets" were a popular home built regenerative shortwave receivers of the 1930s. Designed by amateur radio enthusiast Walter C. Doerle of Oakland, California. Doerle's regenerative radio designs were published in many amateur radio magazines in the 1930s. Doerle's Short Wave Set designs were so popular in the 1930s because of the ease of construction and use of inexpensive parts in their design.
Not much is know about Walter C. Doerle or if he was even compensated for the designs featured in the book "How to build 4 Doerle Short Wave Sets" and other vintage publications. The Doerle name lives on as his shortwave set designs are still popular with "Glowbug", amateur radio enthusiasts that enjoy building simple tube radios, of today. Can I still purchase vacuum tubes?
Absolutely, there are many vendors that sell vacuum tubes and high voltage electronic components required for vacuum tube circuits. Many musicians and audiophiles even today love the sound of vacuum tube audio amplifiers as they believe they produce a warmer more natural sound. As such, there are many vendors that cater to their vacuum tube needs.
The type 30 and 32 vacuum tubes, and other components used in this shortwave receiver, are available from the two vendors below. Source of Vacuum Tubes and related components
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Who Writes This Blog?John is an IT professional from Cleveland, OH who enjoys amateur radio, ham radio, metal detecting, Archives
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