A Brief History of Arvin Industries
Arvin Industries started out as the Indianapolis Air Pump company in 1919, their first product was a reliable air pump used to inflate automotive tires.
In 1927, they changed their name to Noblitt-Sparks Industries and sold "Arvin Heaters" which were specialized heaters used in the automotive field. Back in the day most cars were not equipped with heaters. By the 1930s, Noblitt-Sparks had diversified into making radios for the automobile industry. In addition, they made Silvertone branded radios for Sears.
In 1950, Noblitt-Sparks changed their name to Arvin Industries. While still a leading automotive supplier, they branched out into consumer electronics and appliances. My Arvin 33R78 Stereo Radio was built in 1963.
Arvin Industries left the consumer electronics and appliance market in the early 1970s but still has as a reputation for building quality products in Automotive and Research & Development fields.
My Arvin 33R78 worked perfectly back in 1985. But slowly over time it developed an annoying AC hum as the electrolyte in the power supply capacitors dried up. Recently the FM Mono and Stereo modes of the radio ceased to work altogether which made me think it was time to do a full restoration on this marvelous old radio.
****Caution Electrical Hazard****
The Arvin 33R78 Stereo Radio does not employ a transformer to isolate the AC line current from the chassis. AC Power directly out of the wall is rectified/filtered and used for the B+ Voltage for the vacuum tubes. Tube filaments are configured in series so as to drop the line voltage to the proper voltage levels for the vacuum tubes.
Transformerless designs, as used in the Arvin 33R78, had a metal chassis connected to one side of the power line. While the user is perfectly safe from electrical shock due to the insulated cabinet and knobs, you need to take extra precautions when servicing the radio when removed from the cabinet.
FIRST UNPLUG THE ARVIN RADIO FROM THE AC OUTLET! Speakers are removable and come with long speaker cords. Unwind the speaker cords and unplug from the Arvin Stereo.
Remove left and right speakers from the wooden cabinet and set aside. Also remove the knobs from the front of the Arvin Stereo.
Remove the four screws that hold the back cover onto the wooden cabinet.
Notice that the internal speaker wires are soldered to jacks on the back cover and that the electrical cord is disconnected when the back cover is removed.
You have to remove several screws from the bottom of the cabinet in order to remove the chassis.
Two nuts on the left side hold the chassis to the front of the cabinet, the second one is directly below the one circled in the picture.
Two nuts on the right side hold the chassis to the front of the cabinet, the second one is directly below the one circled in the picture.
I recommend unsoldering the internal speaker wires from the back cover then insulating the exposed ends with electrical tape or wire nuts. It is easier to work on the chassis with the back cover out of the picture.
Make sure you unsoldering the second pair of internal speaker wires and insulate the ends as well. The yellow speaker wire just came off without unsoldering. Possibly a cold solder joint.
Finally the chassis is free and clear of the wooden cabinet.
Cleaning and Lubrication
Notice the poor repair job someone did when replacing an electrolytic capacitor.
Here is the chassis and printed circuit board fresh out of the wooden cabinet. Notice how dusty and dirty.
Here is the chassis and printed circuit board after I cleaned it with compressed air. Much better looking!
I used contact cleaner to clean the contacts in the variable resistors. There is a small opening next to the terminals of the variable resistors that you can spray contact cleaner into.
I use Labelle 109 model train oil to lubricate the shafts of all variable resistors.
Make sure you lubricate the pulleys for the dial indicators!
Test Vacuum Tubes
Electrolytic Capacitor Replacement
C2A (80uF), C2B (30uF) and C2C (40uF) are all housed in the metal cylinder circled in the picture.
You must jumper together where the grounding tabs of C2 where connected to the printed circuit board. C2C was replaced with a discrete 47uF 25Volt Capacitor as seen in the picture. Make sure you get the polarity correct!
C2A was replaced with a discrete 100uF 150Volt Capacitor, C2B was replaced with a 47uF 150Volt Capacitor. Once again, make sure the capacitors are polarized correctly.
C1 (120uF) was replaced with 220uF 150Volt Capacitor. Get the polarity right!
Don't forget to replace C3, a tiny 4uF capacitor towards the front left of the printed circuit board. I replaced this capacitor with a 4.7uF 50Volt capacitor.
Testing and Troubleshooting
As mentioned, the chassis of the Arvin 33R78 is "hot", meaning it is connected directly to the AC Line. Care must be taken when testing and troubleshooting. When working on a electronic equipment with a hot chassis, I always wear rubber soled shoes and use the old tried and true practice of sticking one hand in my pocket and using the other hand to manipulate test leads and switches. I also recommend attaching the insulated knobs to the shafts of the front controls. Disconnect the power before making any changes to the chassis or the printed circuit board!As you can see from the picture, I used test leads to connect the cabinet speakers to the audio transformers mounted on the chassis.
Get the Arvin 33R78 Stereo Radio Schematic
Arvin 33R78 Stereo Radio SchematicThe Arvin 33R78 Stereo Radio Schematic with parts listings and troubleshooting documentation is available from SAMs Photofact for around $20.
The Arvin 33R78 Chassis ready for testing and troubleshooting.
Testing the Arvin 33R78 Chassis
Cleaning up the wooden cabinent
Arvin 33R78 cabinet before cleaning and polishing.
Look how nice the cabinet looks after several applications of Old English Lemon Oil.
I even treated the inside of the cabinet to the a good cleaning and some Old English!
Cleaning the Knobs
Here are the knobs before cleaning.
An old toothbrush is the best tool to clean between the ridges of the knobs. It also prevents the knobs from getting tooth decay!
Here is a picture of the freshly cleaned knobs.
Installing the chassis back into the cabinet is just the opposite of removal.
Make sure you properly fasten the chassis into the cabinet. If a fastener or screw is missing get a replacement from your junk box or local hardware store.
You may need to use a Dremel to cut the shaft lengths of replacement screws.
Make sure you solder the left and right channel speaker connections back to the terminals on the back cover.
The back cover back in place and the speaker wires neatly wound around their caddy.
My restored Arvin 33R78 Stereo Radio in Action!
The restoration of this vintage Arvin 33R78 Stereo radio was most gratifying. It took my mind off of the stresses of my daily job and reminded me of a simpler time when people had the time to sit around and listen to the radio for enjoyment.
Radio Restoration Books On Amazon
I consult books often during radio restoration. I grew up in the transistor and rectifier era and these books taught me a lot about vacuum tube and selium rectifier technology.
The Yaesu FT-1900R is a 2 Meter FM Transceiver that is capable of up to 55 Watts transmit power. This radio is setup for mobile use and requires 12 Volts 11 Amps to power it. With the addition of a bench DC (Direct Current) power supply, this transceiver would be at home in any Ham Shack.
I myself am a newbie and I ordered the Yaesu FT -1900R from Amazon as my very first radio once I got my Technicians License. Once ordered, the radio showed up two days later as I am subscribed to Amazon Prime and get automatically upgraded to two day shipping.
Upon opening the package, I was immediately impressed with FT-1900R. The body of the radio is one massive heat-sink eliminating the need for a noisy fan to keep it cool. There is a minimal number of switches on the front, this was accomplished by using menus to change different parameters of the radio that are not accessed often. I immediately attached the radio to a DC bench power supply and to an Arrow J Pole antenna I mounted in our attic and was able to pick up multiple transmissions.
The manual was easy to understand, it took me about five minutes to set the PL Tone and to save my first repeater frequency into memory. I then proceeded to store a couple of other repeater frequencies. You can store up to 200 frequencies in memory. One of the great features of the FT-1900R is that you can scale back on the transmit power, by default it transmits at 55 Watts. I can see that it would be important to scale back transmit power if you are running off of a battery in an EMCOM (Emergency Communications) situation and need to get the maximum battery life.
The buttons on the front of the FT-1900R and on the microphone are illuminated for easy nighttime use. You can also recall frequencies in memory from the illuminated keypad on the microphone which would be ideal for mobile operation. On an hour long rag-chew, transmitting at 55 Watts, the case of the FT-1900R does get hot to the touch. I believe the aluminum chassis was designed this way to dissipate heat. The receive audio is very clear audio and all repeater contacts indicate that they can hear me clearly.
There are some features, such as WiRES-II, which would appeal to the more seasoned Amateur Radio Operators. WiRES-II allows you to communicate by Amateur Radio and the Internet.
The FT-1900R was a great purchase and I definitely recommend this radio to any amateur radio enthusiast.
Video of Amateur Radio operator using his FT-1900R to listen to transmissions from the International Space Station as it hurtles by overhead!
As any owner of a Kenwood TS-520S can attest to, it is a real pain to calibrate the analog tuning dial so that the frequency read is the truly accurate. The process involves changing the function switch to CAL-25kHz, this is an internal reference signal, then you turn the main tuning knob until you zero beat the the internal reference signal, adjust the dial scale until it shows the correct reading. In order to maintain turning dial accuracy, you have to do the dial calibration again when changing bands or modes of operation (Upper Sideband, Continuous Wave, Lower Sideband). I thought it would be cool to eliminate all of this calibration nonsense by adding a digital frequency counter to the to the TS-520S so that you always have the tuning frequency accurately displayed.
Video showing the process of zero beating for dial calibration against station WWV
Easier procedure for analog dial calibration by K4TFJ
The Bad News
One of my goals was to provide a readout of the current tuning frequency on the frequency counter but it does not look it is quite that simple. I am not sure what "Magic" the DG-5 does to directly perform a readout of the tuning frequency. It somehow does this while monitoring the signals of the CAR OUT, HET OUT, and VFO OUT jacks on the back of the TS-520S.Here are the outputs and their frequencies:VFO OUT: Same frequency variation not matter what the setting of the Band Switch.With both the Main Tuning Knob and Sub-dial set to 0: 5.5MHZWith the Sub-dial set to 600 and the main tuning dial set to 0: 4.9Mhz CAR OUT: Constant 3.2987Mhz no matter where the tuning dial or Band Switch are set.HET OUT: Changes with the Band Switch setting:1.8 - 10.693MHZ3.5 - 3.1239Mhz7 - 15.893MHZ14 - 22.892MHZ21 - 028 - 028.5 - 0I have not yet solved this riddle.
The Good News
If you connect your frequency counter to the VFO OUT on the TS-520S, with some simple math you should be able to determine the true tuning frequency.For you consideration:With both the Main Tuning Knob and Sub-dial set to 0: 5.5MHZWith the Sub-dial set to 600 and the main tuning dial set to 0: 4.9Mhz 5.5MHz - 4.9MHz = 600kHzFormula:True Tuning Frequency = Band Switch + + 100kHzFor example, if the Band Switch is set to 7 and frequency counter reading is 5.200MHz, the true dial frequency is:7MHz + 200kHz + 100kHz = 7.300Mhz
Connecting your Frequency Counter to the TS-520S VFO Output
I use a short video cable with RCA jacks on the ends to connect my frequency counter to the VFO Output on the back of the TS-520S. I removed the RCA jack from one of the cable ends, stripped the insulation back and separate the outside braid from the internal conductor. I then tinned the ends of the outside braid and internal conductor so that they would not come unwound and connected them to the Fahnestock clips which serves and input terminals to my frequency counter. See area circled in the above picture.
The Frequency Counter in Action!
Adding a PIC based frequency counter is a great way to calibrate your tuning dial and provide digital accuracy to your vintage Kenwood TS-520S SSB Transceiver.
Knowing my new interest in Amateur Radio, my father-in-law, or the "Old Man from California" as he likes to call himself, offered me his old ham radio equipment that he no longer used. I readily agreed. In the next couple months, my father-in-law shipped me the following from his collection:
- Kenwood TS-520 SSB Tranceiver
- Azden PCS-3000 2M FM Transceiver
- Ten-Tec Century 21 CW Transceiver
- Yaesu FRG-7700 All Mode Transceiver
- MFJ 949C Antenna Tuner
This encouraged me to obtain my Amateur Radio Technician license. As soon as I passed I immediately started fiddling with the Azden PCS-3000 2M Transceiver. I installed a J-Pole antenna, made by Arrow Antenna, in the attic and routed the coax transmission line through the closet on the first floor and to my Radio Shack in the basement. I knew that the J-Pole antenna was closely impedance matched to the RF output of the Azden PCS-3000 so that no Antenna Tuner was required. I set the frequency offset and enabled the PL Tone switch on the top of the transceiver and was ready to make contacts!
Despite repeated attempts I was unable to trigger the local repeater. I then decided to put my MFJ 949C Antenna Tuner in series with the PCS-3000 and the J-Pole antenna. I set the Antenna Tuner to direct mode bypassing the internal LC circuit. The issue became evident. Keying the microphone produced no RF output to the antenna! The cross needle meter on the Antenna Tuner did not indicated any forward or reflected power. Time to take apart to the PCS-3000 to determine the issue!
Disassembly - Loosen Control Unit Knobs
Time to figure out what's "broke", first you must remove the detachable control unit. This is done by loosening the knobs on each side of the radio.
Disassembly Tip - Organization is important!
When disassembling a radio, I carefully place the parts into two bins, one bin for the larger parts and a smaller bin for the screws.
Disassembly - Remove the control unit
Pull the control unit strait forward, the control unit attaches electrically to the body of the radio by an edge connector.
Dissaembly - Remove the mounting rails
There are two mounting rails, one on each side of the radio. Two counter sunk Philips screws hold them in place. Remove the screws then pull the rails off.
Disassembly - Top cover Removal
The bottom cover is held in place with four screws, one at each corner of the cover. Remove the four screws and pull the cover off. The speaker is attached to the bottom cover, you will need to disconnect the speaker from the printer circuit board.
The RF Amplifier Module
The Taiyo VP-15E13LF RF Module is circled in red, I believe that this is the failed component but need to do some checks first.
Voltage and Signal Checks
All voltage and signal measurements are taken with reference to the metal chassis. I attached the negative lead of my Multimeter and ground lead of my Oscilloscope to the internal metal chassis when making measurements. Signal measurement is in Volts Peak to Peak.
PA Board Input Checks
Measurements taken on connector circled in red. PIN5 12 Volts DC, PIN9 9 Volts DC, PIN4 9 Volts DC when MIC keyed. PIN1 9 Volts DC when MIC NOT keyed.
PA Board Input Checks (Continued)
You should see a small FM signal (under 1 Volt) on the IN pin circled in red when the MIC is keyed.
RF Amplifier Module Checks
IN, VC, VD, OUT are marked on the PA printed circuit board. IN should be a small FM (under 1 Volt) signal when MIC is keyed. VD should be around 9 Volts DC, VC should be 12 Volts DC. OUT should be an FM signal of several volts when MIC is keyed.
My Troubleshooting Results
I have determined that all the proper voltages and signals were present going into the PA Circuit Board. I have also determined that the proper voltages where present on the pins of the Taiyo VP-15E13LF RF Amplifier and the proper FM signal was present on the IN pin of the RF Amplifier Module but that no signal was present on the OUT pin of the RF Amplifier Module. This leads me to believe that the RF Amplifier Module is defective.
The RF Module is made of Unobtainium
The Taiyo VP-15E13LF RF Amplifier Module part has been discontinued. I like to say is that it is now made of "Un-obtainium". I cracked the RF Module open to see if there was any serviceable parts. The RF transistors that are in the Taiyo VP-15E13LF RF Amplifier Module are available but our expensive as they have been discontinued as well. The RF transistors were too expensive to justify the repair of this aged 2M Transceiver that is worth under $100 in working conditions. Time to look for alternatives.
Inside the Taiyo RF Amplifier Module
What's inside the Taiyo VP-15E13LF RF Amplifier Module
The M57737 RF Amplifier Module
Pinout and package dimentions of the Mitsubishi M57737 RF Amplifier Module
Source for replacement Mitsubishi M57737 RF Amplifier Module
As mentioned, the pin layout of the the M57737 is slightly different. The M57737 does not have any ground pins but instead the metal base of the module is ground.
Make sure you apply heat sink compound to the back of the RF Amplifier Module before mounting.
Here are the connections of the M57737 to the PA Board:
M57737 Pin | PA Board Connection
Pin1 ============ IN
Pin2 ============ VD
PIN3 ============ VC
PIN4 ============ Anode of D30 which is connected directly to OUT
Metal Case ======= Any connection designated as G
The Transplanted M57737 RF Amplifier Module
The M57737 mounted and soldered in place. Notice the ground connection between the M57737 metal case and G on the PA printed circuit board.
A Leap of Faith
I had no idea if the replacement Mitsubishi M57737 RF Module was going to work. It was a $50 gamble! That was the cost of the replacement part. I could easily power it on an smoke the new RF Amplifier module.
I moved the Azden PCS-3000, with the newly installed RF Amplifier module, over to the desk in my Radio Shack, connected power and attached the antenna output to my MFC 949C Antenna Tuner. I then set the Antenna Tuner to use the built in dummy load.
Upon power up there was no smoke....whew....the PCS-3000 was working correctly in receive mode. I checked voltages at VC and VD points on the PA printed circuit board, they look correct.
Time to key up the MIC and transmit into the Dummy Load. Success! I was reading about 100 Watts Peak to Peak as forward Wattage on the cross-hair meter on my Antenna Tuner.
Once connected to my J-Pole antenna, I was able to trigger our local repeater and establish contact with a fellow Ham on the 2 Meter band.
Bench testing my Azden PCS-3000 after the RF Amplifier module implant.
The Down Side
As part of my testing, I decided to try low power mode which is accomplished by pulling the Squelch control out. Low power mode effectively cuts the RF output power in half. I heard a "pop" as soon as I keyed the MIC in low power mode. It blew the inline fuse in the power cable. I immediately turned off my 12 Volt bench power supply. My first concern was, did it blow the newly installed RF Power Amplifier module? I replaced the inline fuse with a suitable size, pushed the Squelch control back in, putting the PCS-3000 back into high power mode, and turned the 12 Volt bench power supply back on. The PCS-3000 sprang back to life and when I keyed the MIC I was still able to contact our local repeater.....whew.
My solution to this problem was to not use the low power mode and to place a sticker on the top of the rig warning to not use this function.
Back in Service
My Azden PCS-3000 back in service in my Radio Shack!
My transplant of a similar Mitsubishi RF Amplifier module into my vintage Azden PCS-3000 2M Transceiver was a success! I am hoping that this Hub will help you in diagnosing and fixing a "no RF output" problem with your PCS-3000 was well.
What is a Doerle Short Wave Set?
Doerle "sets" were a popular home built regenerative shortwave receiver 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 and Boat Anchor amateur radio enthusiasts of today.
Regenerative Receiver: Type of receiver that feeds a portion of the output signal back to the input, in a positive feedback configuration, in order to boost the amplitude of a radio signal many times.
Glowbug: Term used by amateur radio enthusiasts to describe a simple home built tube-type radio set, reminiscent of the shortwave radio craze of the 1930s.
Boat Anchor: Obsolete tube type radio sets that are so heavy and cumbersome that they could be used as a boat anchor!
It's the 21st Century, 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 vacuum tubes and other components used in the Doerle Short Wave Set I built are available from the two vendors below.
Source of Vacuum Tubes and related components
Building a Two Tube Doerle Shortwave Receiver Set
Step 1 Source Vacuum Tubes and Electronic Parts
I found everything required to build my Two Tube Doerle Shortwave Radio set from Antique Electronic Supply (AES), the link to this company's web site was provided earlier.
Step 2 Design and Build Cabinent
The cabinet is made of salvaged wood from shelves that used to hang in my garage. I used degreaser to remove motor oil from the surface. Once degreased and dry, I used a palm sander to smooth out dents and imperfections.
The cabinet for my Doerle Shortwave Receiver is going to be open type. Basically, L shaped with the top piece used as the front panel with all of the controls, and a bottom where the majority of parts are to be placed.
The shafts for the Tuner, Regeneration, and Filament controls are not long enough to protrude through the front of the 3/4 inch wood. So I decided to carve out areas in the wood so that the shafts could protrude through the front.
Next, it was time to layout the parts on the front panel and bottom of my Doerle Shortwave Receiver. I then mount parts with screws and checked for fit and placement.
I used tape to mark the depth of holes I want to drill so as not to drill right through the wood.
I used a Wooden Hole Saw Set to drill concentric holes 1/2 deep into the back of the front panel.
I then used a screwdriver like a wood chisel to remove the remaining wood between the concentric holes drilled by the Hole Saws.
This is how the back of the front panel looks after the remaining wood was removed from the indentations created. The indentations were then sand to remove any roughness.
I created a paper template to be used later to plan out the wiring.
Time for two coats of polyurethane with light sanding between each coat!
I glue aluminum foil, the same type you use to wrap food in, to the back of the front panel. Elmer's White Glue works fine. This foil will be tied to circuit ground in order to reduce the effects of hand capacitance during operation.
Finally, some rubber feet on the back side of the bottom panel.
Step 3 Final Mounting of Electronic Parts
It is easiest to mount the variable capacitors and variable resistor to the front panel first!
Finally, you can mount the hardware on the bottom panel.
Step 4 Wiring
Creating a wiring diagram a head of time makes wiring easier.
Here is my Doerle Shortwave Receiver ready for wiring.
First, I wired all of the ground connections (Black wires).
Next the 90 Volt circuit (Purple wires)
Followed by the tube filament circuit (Red wires).
Finally the 45 Volt and Tuning circuits (Yellow and Blue wires).
Step 5 Winding the Coils
The coil that is part of the tuning tank circuit, and the regenerative coil, are mounted to a removable 8-pin octal base. You plug in different coil assemblies into the octal socket on the bottom panel of the radio to change Shortwave Bands.
Here is a picture of the coil assembly for the 15-45 Meter Bands.
Next you have to scrap off the varnish insulation on the 22# magnet wire in order to prep for soldering.
Next you feed the bare part of the magnet wire through the proper pins and solder.
Here is top view of the coil assembly.
Finally, check each coil's continuity at the pins.
Step 6 Final Prep
Install the Type 30 Triode Tubes, plug the coil into the socket, label connections.
In addition, label the front controls and headphone connections.
Step 7 Obtain Suitable Power Supply
In my "Battery Box", I use two D batteries for the 2 Volt filament voltage. I connect many 9 Volts in series to obtain the 90 and 45 Volts needed to power the receiver.
Fahnesstock Clips on the back of the "Battery Box" provide access to the required Voltages.
Connect the Doerle Shortwave Receiver to a suitable power supply, antenna and ground. I use my external G5RV Amateur Radio antenna and main water pipe that comes into our house as a ground. In addition, connect high impedance headphones to the front.
Front view showing the Tuning, Filament, and Regeneration controls. In addition, connections for headphones.
Step 9 Testing
Set the Tuning, Filament, and Regeneration controls to mid position. You should hear atmospheric "hiss" from the headphones, once the power supply, antenna, and ground are connected. Use the Tuning knob to select AM broadcasts. Once selected, adjust the Regeneration control counter-clockwise to the point of where you hear oscillation, then turn it clockwise slightly until the oscillation stops and the AM broadcast is clear.
This is the point that the Doerle Shortwave Receiver is at maximum gain. Turn the Regeneration control further clockwise to reduce receiver gain if the AM broadcast is overpowering the headphones. The only time you should need to adjust the Filament control is if your A+ batteries is getting weak. Adjust the control until there is 2 Volts at the filament pins of the Type 30 vacuum tubes.
Here are some troubleshooting tips if your Doerle Shortwave Receiver is not working as expected.
No sound from headphones:
This was a most gratifying project. When not in use it is proudly displayed on a shelf in my basement "Man Cave". Building a Doerle Receiver is a great way to learn about electronics past.
Who Writes This Blog?
John is an IT professional from Cleveland, OH who enjoys amateur radio, ham radio, metal detecting,
Copyright © 2017
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