RE: Unknown 1 tube regenerative radio -
klondike98 - 04-14-2023
Mike, I will check to make sure I drew the headphone wiring correctly. The lead labeled WHT is the antenna connection I believe. BLK is for A- and B- , Red is A+ (2v) and the unlabeled lead with the arrow is B+ (45v) if I understand MrFixr55 and Chas correctly.
Chas, is the stub of a wire in the fixed coil (#4) supposed to connect to the chassis? It is physically located right next to #2, a chassis connection, and perhaps has simply lost connectivity at the connection point. I do not see any provision in the cabinet to make an earth ground connection.
RE: Unknown 1 tube regenerative radio -
morzh - 04-14-2023
Bob
Because WHT was connected to what I thought was GND (now I think it was but then you tried to cross it out, but to me it still looked like GND) then I thought the free end was Antenna.
If the WHT is Antenna then the Free end is GND.
RE: Unknown 1 tube regenerative radio -
klondike98 - 04-14-2023
Thx Mike. Hopefully I can get my soldering iron in there and get that stub #4 reconnected to the chassis without messing it up. Then I might have a radio that has a chance of working.
RE: Unknown 1 tube regenerative radio -
klondike98 - 04-25-2023
Some more progress on this one. The chassis was very simple but a bit rusty. I took it apart to clean it up some, of course, in the process I managed to break one of the coil connections for the trimmer/regen coil, but fortunately was able to get it repaired.
I found a replacement for the missing knob on eBay for a very reasonable price and while not an exact match does, I think, fit the bill pretty well (its the center knob in the picture).
The grid leak resistor has drifted and is 40% high (2.8Meg instead of 2.0Meg) but I decided to leave it alone for now. Here it is part way through the clean up process.
[Image:
https://www.dropbox.com/s/dnokn0bkwvnpfu6/unknown_11.jpg?raw=1]
It all went back together OK. Some of the wiring connections are made with a small machine screw and nut. I wonder if this might have been some form of kit that the consumer put together. I hooked up the A+ as 2v and B+ as 45v. Since I did not know what frequency range this might receive in I used my modulated signal from my generator and coiled an output signal wire around the antenna wire a couple turns.
[Image:
https://www.dropbox.com/s/6cp70zq5hce4ftl/unknown_12.jpg?raw=1]
I was able to hear the modulation tone through some period earphones (I know it was tone because the fellow who owned the signal gen before me modified it to be able to switch between two modulation frequencies...very convenient to be sure of what you are hearing) by adjusting the radio tuning capacitor to a specific spot and also adjusting the trimmer/regen coil to a specific spot. My generator was at 1.090 megc. I was also able to hear the modulation tone at other generator frequencies both above and below 1.09 but that seemed to be the loudest. If I moved the radio tuning capacitor to any other position I could not hear anything on any generator frequency. It was only the unique combination of radio tuning cap position plus regen position that I was able to hear the signal generator so I'm not sure things are working properly but at least I heard something. Any further advice is most welcome.
RE: Unknown 1 tube regenerative radio -
klondike98 - 04-26-2023
Time to write the final chapter on this restoration. I went back and checked all the connections. Sure enough, one of those grommet style connections on the coil was not making proper contact with the connection lead the grommet was holding so I added in some copper braid to ensure it was solid. It was the #1 connection seen on the coil in an earlier post. The pic shows the braid which went through the grommet and was trimmed off on the other side.
[Image:
https://www.dropbox.com/s/k0f34tuozw450yn/unknown_13.jpg?raw=1]
When I tested reception with my SSTran I was able to tune in on the broadcast band nicely. I could not pick up our one local AM station but I only have about 30 feet of antenna. Here's the radio back together. It will now head back to the
Bandon Museum.
[Image:
https://www.dropbox.com/s/p7r4qidsusczqwo/unknown_14.jpg?raw=1]
Here's the as completed schematic:
[Image:
https://www.dropbox.com/s/i7vlsy2t0hy8ojh/unknown%201%20tube%20schematic.jpg?raw=1]
RE: Unknown 1 tube regenerative radio -
GarySP - 04-26-2023
Beautiful restoration, Bob! Amazing considering what you started with! Take care and BE HEALTHY! Gary
RE: Unknown 1 tube regenerative radio -
MrFixr55 - 04-26-2023
Fantastic job, Bob. A very interesting radio, very interesting graphics, built in a very interesting (and painful) time! I hope that eventually someone identifies it!
RE: Unknown 1 tube regenerative radio -
klondike98 - 04-27-2023
Thanks guys, it was a fun one. Used new skills on the cabinet and learned new things on the chassis.
RE: Unknown 1 tube regenerative radio -
radiorich - 04-27-2023
Hello Bob,
Wow, that set looks really nice so is this going to be just static display at the museum .
Sincerely Richard
RE: Unknown 1 tube regenerative radio -
klondike98 - 04-27-2023
Thx Richard. Well, it’s does work now and I could set them up with the power supply, AM transmitter and earphones for demonstrations but it is primarily a shelf piece, not unlike most radios in our own collections. I restored a Radiola 60 for the museum several years ago and we had it set to play old time radio shows from an AM transmitter through out the day. That worked OK for awhile but it would often either not get turned on in the morning or off at night so we decided to not keep it on anymore.
RE: Unknown 1 tube regenerative radio -
palegreenthumb - 04-28-2023
Great work! I agree with the comment that it seems like a World's Fair or Century of Progress type promotional radio. Absolutely fantastic!
RE: Unknown 1 tube regenerative radio -
morzh - 04-28-2023
Great work, Bob! This is sure one unique radio.
RE: Unknown 1 tube regenerative radio -
klondike98 - 04-28-2023
Thanks for reminding me about that Century of Progress 1933 Fair reference that Mr F mentioned earlier. I searched on that and a radio museum image popped up that identifies the radio as a Stewart Warner “Century of Progress” radio from 1933. I searched the worldradiohistory.com site for a 1933 Stewart Warner catalog but came up empty. Here’s the radio museum link:
https://www.radiomuseum.org/r/stewart_wa_century_of_progress_unknown.html