Today I found at a second hand shop an AWA Standard six receiver model C38 from 1927 in good condition. I was able to purchase this radio for a very good price. When I purchased this radio I assumed due to its age it would be a TRF receiver. Further investigation reveals this receiver is in fact a superheterodyne. I found it surprising that AWA were manufacturing superheterodyne receivers in 1927, yet my AWA Radiola 45 from 1930 is a TRF receiver. I'm curious to know why AWA switched from a superheterodyne to a TRF design for their Radiolas?
I also discovered that the original UX199 triode valves had been swapped with A609's which have a different filament voltage. I will see if I can find six UX199's to restore this receiver.

Superhet was invented around 1911 & I have seen early examples & one. I have to deal with one at some point it has around 10 WECO tubes (Trench Valves) and a modulation transformer and the weirdest push pull stages I have ever seen.

Marc

Hi Samt,

I think I will have to head down to Hobart ASAP to see if there are any more gems left at those antique stores. The C38 sounds like a great find.

I have an empty C38 case that I would love to fit a chassis into. The only problem is not knowing what to look for. Even finding a schematic is proving troublesome. How have you gone with your radio restoration? Any luck with the 199s?

Regards, Frank.

Even that they are wrong tubes, a 7806 with heat sink would handle their 6V filament. Radio museum list UV199 as rare and it had several numbers & bases. It is a 3V filament. I not it is a universal valve where A609 is radio & TV.

It could be got going with A609 in the interim if its got a full set.

Marc

It would be nice to have some photos of your radio on the Radio Museum?

https://www.radiomuseum.org/r/amalgamate_radiola_standard_6_c38.html

Hi Frank, Mark and Gary.

I have so far found five good UX199's. I also found a great article and a circuit for the C38 in the January 2003 edition of the HRSA magazine Radio Waves. I will email a photo to Brad to include. I would like to send a photo to Radiomuseum as they do not have one, however the front of the cabinet is missing some veneer and one of the tuning knobs is missing. I will see if I can find a matching tuning knob or have the existing knob reproduced.
AWA used a similar design to the American RCA superhets and potted the IF coils and transformers in a steel box filled with wax.

Hi Samt,

Just thought I would ask is your radio the 1927 model with the Emmco dials for tuning or is it the 1928 model with the AWA tuners.

If it has the Emmco dials I may be able to help with a tuning knob. I will have a knob which is very similar which is a very dark brown rather than black. It is yours if you want it. Just email me your details and I will post it to you. My email address is open.

Regards, Frank.

Photos uploaded to Post 6.

I'm not really into coffin radios but I do like that one.

Hi Samt,

I am so glad you sent in the photos. It is great to see the insides of one of these sets. My set is a big fat empty at the moment, but I do want to turn it into a working radio that looks close to right at least.

One thing I did notice is the tuning capacitors. Are they AWA or Emmco capacitors? According to the information I saw C38 radios with AWA dials were supposed to have AWA capacitors, but that information may be wrong.

Regards, Frank.

Hi Frank,
Sorry about the late reply. The tuning capacitors are AWA. It is a 1927 model according to the inspection slip inside the cabinet. It uses the earlier circuit with no Brach-Stats fitted and uses six UX199's. The 1928 model used four UX199's, and two DEP410's as the output valve. Brach-Stats were connected in series with the valve filaments on the 1928 model and changed in resistance with varying A battery voltages, in theory prolonging the life of the valves. The earlier 1927 model which I have has a hand rheostat to adjust the filament voltage so has an extra knob. The audio coupling transformer on top of the chassis is not original but a later repair. The original transformer is in the metal box underneath the valve sockets potted in rosin/wax. It looks like it went open circuit and a new transformer was mounted on top. After 90 years the wax tends to crack and move, breaking the fine wires leading to the IF and RF transformers. Repair involves melting the wax to access the coils and transformers. If you like I can scan and email you the circuit for the C38.

The C Bias Battery I found under the chassis still had 2 volts across it after 90 years.

Hi Samt,

I would love a copy of the C38 circuit.

It sounds like your radio may be a transitional radio. The tuning capacitors are a different design to the 1929 AWA tuning capacitors so I presumed they were Emmco capacitors. It was also very interesting to see that the sockets were Benjamin sockets. The way things are looking the chances of creating a reasonable reproduction are getting better and better thanks to your photos.

Regards, Frank.