Hi everyone,

Recently I've been asked to restore an old Desoto car radio dated from the 1940s.
I originally thought that it would be an American made radio, but on opening the chassis boxes up I find "Made in Australia under licence" inside on the valve line up chart stuck under the lid.

The radio is in three parts, the vibrator power supply, the radio itself, both of which are bolted via 1 large bolt to the firewall of the car, and the radio control panel which has "Desoto" written on the large chrome speaker grill.
The controls are via Bowden cable to the radio itself.
There seems to be a blanking plate for where push button tuning may have been an option.
The dial glass is long gone sadly.

The valve line up is 6BA6, 6BE6, 6BA6, 6AV6, and 6V6GT, the rectifier in the power supply box is a 6X5, the speaker is a permag one around 5 inch cone.

The main caps inside are UCC branded.

Anyone have any idea who actually made it?

Ill take some photos later when I get a chance.

Thanks,
Raff

That valve lineup looks a bit HMV and with those valves more like 1950's. If it was a genuine CDPD radio it is likely that it would appear in the factory workshop manual.

Other possibilities Ferris / Astor. I have an Astor here but it is actually a known & has the 1940's valves in it. I also have a Genuine one from a MKII Zephyr & its "Smiths Radiomobile" so HMV. I also have the vehicle to put it in.

Holdens often used NASCO which were "Airchief" (Firestone Tyre & Rubber)

A lot of these were badge engineered & used in everything with only a fascia change.

It would be a good idea to post photos. Look for chassis stamps like KJ.

Marc

That's a popular line-up for car radios. I find these matches (and there may be more);

Make, Model, Year

Airchief, CR, 1950
Airchief, CS, 1950
Airchief, JL amended, 1953
Airchief, JM amended, 1953
Astor, CR, 1951
Astor, CS, 1951
Astor, FK (Ford), 1953
Astor, FQJ (Ford),1953
AWA , 902, 1949
AWA , 903, 1949
AWA , 904, 1949
AWA , 905, 1949
AWA , 906A, 1949
AWA , 902A, 1954
AWA, 903A, 1954
AWA , 904A, 1954
AWA , 905A, 1954
AWA , 906A, 1954
Ferris, 89, 1952

Thanks for the info guys.

After looking at the radio and checking again, I suspect it might be an AWA 902/3/4/5/6a.

The values I can find inside seem to fit the circuit diagram I found in my AORSM volume 8.

Lucky as I only have volumes 2,3 and 8 of the AORSM, its a great resource.

I'm thinking when I can afford it I might spring for the CD version.

I've ordered some high voltage caps, so when I next get at the radio, I'll keep you guys updated, and take some photos.

Raff

Some Mopar (Chrysler Spare Parts & Accessories Division) car radios were made here under licence by AWA.

This De Soto radio could be based on the AWA 902A, 903A and 905A (the 6 volt versions), though with some mechanical differences.

AWA 902 Circuit Diagram.

Many thanks for the circuit!

That will help immensely

Now I just have to wait for my capacitors to arrive.

Thanks again,
Raff

Do remember to check resistors as you go. They normally go high, so any high by 10%, or more in my book, are replaced.

This saves grief & rework later.

Marc

Well I got the old girl working fine.

Found all the paper caps leaky, no surprises there, replaced them all along with the 3 electrolytics.

Found the 6AV6 valve has an intermittent plate to everything else short, not good, lucky I had a spare.

The IF was way out in spite of being sealed at the factory many years ago, so I did a full alignment using my rebuilt Motorola r1200A service monitor.

Ive been listening to it daily for the last couple of days to make sure its going to behave itself. As there are no close AM stations around here, I use my home built AM 2 valve transmitter based on the "mate" published in Electronics Australia many years ago.

Good work.

The last photo above should be referenced to by all that intend fixing a radio. Note the 14pF cap on the gang, likely AWA branded. There a two forms of these, one is encased like that & the other is not. These are of a mica wafer & clamp construction & I have not had one of them fail in a set past mid 1930s

The big black "Mud" Tarred & not feathered ones shown split their jackets mainly at the end (visible in photo) and I have seen 70's caramel coloured Polyesters do similar.

The danger here (and I have seen it) apart from moisture, is that these can then fracture at that end point & short. Deep down these are wax paper & should be gotten rid of. It is of no surprise that they were found to be leaking like sieves and rarely do I waste time testing them.

I did actually send the results of a batch from a couple of radios to "Radio Waves" in response to a previous article, in that publication. There is a quote as to how bad the leakage can be, in a NP cap before it has a significant effect, but zero leakage is better, so you don't tolerate any leakage now & use a modern cap.

Marc