Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

General Discussion

Forum home - Go back to General discussion

 Identify 1930's radio
« Back · 1 · 2 · Next »
 Return to top of page · Post #: 1 · Written at 10:56:32 AM on 21 August 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 335

Have a chassis built into a custom cabinet of the 1930's era. There are no makers markings anywhere or any indication as to whom made the radio.

The chassis is factory made, well made with welded and finished off joins. All holes are well cut with hole punches, although worked on some of the original wiring is of a good standard and good construction.

Suspect it may be a kit radio, 7 valves with a r.f amplifier stage. If a kit must have been a top range one. The valve lineup 80, two 59's in output, 55,58,57,58.

The radio itself originated from Eastwood in Sydney.

Would very much like to get a circuit diagram for it.

Thanks for any info.

Unknown Radio
Unknown Radio
Unknown Radio
Unknown Radio
Unknown Radio
Unknown Radio


 
 Return to top of page · Post #: 2 · Written at 11:00:07 AM on 21 August 2020.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1376

Sounds like it would have been a good performer. Be careful with the 59 - they can be instantly destroyed with wrong inputs.


 
 Return to top of page · Post #: 3 · Written at 12:39:10 PM on 21 August 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1895

This would be a depression-era radio. Predates ARTS&P. Probably made by one of the many small concerns that started up at that time, trying to make a quid.


 
 Return to top of page · Post #: 4 · Written at 3:31:35 AM on 22 August 2020.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6334

Photos uploaded.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 5 · Written at 7:35:34 AM on 22 August 2020.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 872

Looked at the photos and noted one thing that could be a concern.
The electros are mounted on insulators hinting they may be above chassis potential in a back bias circuit.
BUT the cans are jammed up against the steel of the transformer!
If that is so and the bias is removed there may be glowing plates on the 59's!

The set would be a great candidate for a complete back to bare chassis rebuild.
Have look on this site for my Yackandandra bare chassis rebuild, same colour blue paint inside the chassis.
The electros could be repacked with moderns, alloy cans stripped back to matte finish, strip kill rust and paint chassis.
Pop a few period tag strips to hold stray parts, would look great.

Fred.


 
 Return to top of page · Post #: 6 · Written at 9:49:17 AM on 22 August 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 335

Actually the electro's are earthed, those tags are metal and the paint has been scraped away to make good contact. Other tags have similar paint scrapes and will solder these to ensure good earthing after all these years. Same for the large variable capacitor.

Still looking about for a circuit which I guess would be buried in some old radio publication of that era.

Sure is a classic depression era radio where utmost economy was practiced in its wiring.

Edit: had a close look at the volume control. The pot is a 5k wirewound and the shaft is insulated from the chassis.

The wiper goes to pin 4 G3 of the 58 RF Amp. Pins 4 and 5 (cathode) are linked together on both the 58 RF Amp and the 58 IF.

A wire runs from pin 4 of the RF amp to pin 4 of the IF amp, so this wire wound volume which gets d.c from a large green multi tap resistor varies this voltage to adjust the volume.

A setup I have not seen before.


 
 Return to top of page · Post #: 7 · Written at 12:18:17 PM on 22 August 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4330

A lot of those cans had shake-proof washers, normally on the inside. The insulated shaft probably relates to how it's wired, in many of those sets the shaft was alive to the wiper.

That would suggest that there is what the Americans call a "candohm" resistor across "B" and like STC 58 (Volume 6K) the volume control actually is in the cathode circuit. Beware the earth of that candohm may not be on the end and they have a notourious habit of going open often y corrosion. That was common wiring & it is going to be an autodyne (screen grid).

#58's (6U7) will be Rf amp & IF amp, #57 (6J7) oscillator / mixer. The STC I got had #59 chassis data could not be found for it & the set had been hacked. That one may have agc .

If nothing can be found, reverse engineer it.

I would leakage test those mica caps, some in that style were not overly reliable whereas the ones AWA used later rarely fail.


 
 Return to top of page · Post #: 8 · Written at 5:01:54 PM on 22 August 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 335

Thanks for the comments Marcc. Measured one of the 0.01μF micas (the large Simplex caps) and it was iffy so replaced it, think I will replace the others which are near the #59's as a long term precaution.

The two large green resistors (500K) had gone well high so replaced them.

The set is working and receives stations but still needs attention which will be done tomorrow.


 
 Return to top of page · Post #: 9 · Written at 9:15:50 PM on 22 August 2020.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 872

Good progress!
Keep it going.
Fred.


 
 Return to top of page · Post #: 10 · Written at 10:01:07 PM on 22 August 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4330

50K & 500k resistors, especially when associated with output valves do have a high attrition rate. I normally leakage test the Mica caps in those at 500V with an insulation tester.

I am not a fan of 450V caps anywhere near a #80 (5Y3) or anything that behaves like one, feeding heater valves. Check the voltage on start up. I will not go below 500V: Too many issues with 450's.

Beware of the IF it is highly probable that it is not 455kHz but perhaps175kHz or lower.

Knot in the cable is not on now & the grommet looks like it gone hard. It would look nicer with a cloth one. These are available with moulded plug top.

So far so good. That white thing looks like a padder that adjusts from the top?

Marc


 
 Return to top of page · Post #: 11 · Written at 8:01:40 AM on 23 August 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 335

That dodgy power cord was the first thing pulled out and binned. New modern cord installed and earthed, have some cloth covered cord about and will put it in later. Proper cable entry anchor put in as well.

Found a curious fault that when tuned to 2CR and push against the back of the 3 gang capacitor the signal improves greatly. Same if the chassis is flexed a bit. So suspect an earthing problem.

Just about the pull the chassis out and restart more work.


 
 Return to top of page · Post #: 12 · Written at 10:31:16 AM on 23 August 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4330

That is rather like a couple of 16 & 18 valve "Midwest's" I serviced. Huge chassis but the scanting saw it flex. I was not impressed by their layout & shielding.

I would also look at wiring: The Gang is in most cases (not all) floating on rubber bushes, with an earth strap, which may be missing?

3mm solder wick, will replace it. Did you align the set? If it has a padder, that is set around 600kHz the aerial trimmers with only an aerial attached around 1500kHz. One thing that is often not appreciated, is the fact that where there is a pre amp it and the mixer's antenna coils, need to be on the same frequency, or you get attenuation.

I doubt that fault has anything to do with anything other than the front end aerial stages. Do check the aerial rotors for fouling. Dry joints are still popular & in common use.


 
 Return to top of page · Post #: 13 · Written at 11:02:26 AM on 23 August 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 335

A few mo's ago finished some basic earthing work. The three gang variable sits on brass spacers, removed these, scraped the chassis and underside of the capacitor lugs with a file. Filed clean the brass spacers and before reassembling smeared all with conductive grease.

As drilled a hole and put a gromment for the dial light wires, the original hole feed through was a short waiting to happen.

Upon powering up was delighted to hear 2CR blasting a full volume with just a 3ft length of aerial wire.

Lithgow and Orange commercial stns thunder in.

That's all it was, aged old rusty joins.

Still think a bit of lower band end alignment could help a bit.


Noted Marcc's last remarks, thanks.

Will send a photo later, got more work to do.


 
 Return to top of page · Post #: 14 · Written at 9:06:25 AM on 24 August 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 335

Afraid my joy at having found the problem was short lived when I shifted the radio about. An improvement but not the full cure. Looking at the earthing of the rotor of the tuning capacitor noticed very long wires about a 140mm long running to a earth lug on one of the can electro's.

This was poor practice so installed a earth lug close to the rotor and ran solder wick as a braid.

This resolved any problems, completely stable now and the radio receives perfectly. Even in daytime can hear Sydney stations on a wire aerial thrown out the window. Quite impressed, the 59 push pull output stage really punches out the sound.

Quite frankly I do not believe this radio ever worked properly. Probably being in Eastwood and close to radio stations it worked well enough for the builders usage.

A basic embeded wiring fault.

A photo of the braid earthing and the custom built cabinet which is made out of Queensland Maple with a fiddleback grain has been sent.

Unknown Radio
Unknown Radio


 
 Return to top of page · Post #: 15 · Written at 4:40:06 PM on 24 August 2020.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6334

Photos uploaded to Post 15.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
« Back · 1 · 2 · Next »
 You need to be a member to post comments on this forum.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.