[captainclock1988]

Hello everyone today I took a trip up to Michigan and picked up a 1930s Stromberg-Carlson Tombstone Radio that I need help finding a model number for it because all of the model number information tags are either damaged or missing from the radio and I know there's a website out there that you can use to find a radio model number by typing in the tube line up but I can't for the life of me remember the name of the website and I need this radio's model number to look up some service data for it for electrically restoring it, and also locating a replacement tuning dial for it because the original phoenolic tuning dial is broken and I need to replace it to help make this radio functional and complete again.

See pictures below.

   

   

   

Do any of you guys recognize this radio and what model it might be? 

I appreciate any help you can give me.

Thanks.

[RodB]

Try radiomuseum.org for the tube list. That's a beast!

[morzh]

R-110A

Stewart-Warner.

https://www.radiomuseum.org/r/stewart_wa...110_a.html

[captainclock1988]

OK, yeah, I meant to say Stewart-Warner not Stromberg-Carlson, I tend to get those brands mixed up.

[morzh]

http://www.nostalgiaair.org/PagesByModel...029874.pdf

[Arran]

Really, I used to get Setchell Carlson mixed up with Stromberg-Carlson, but never mixed up either one with Stewart Warner. Stewart Warner was in Chicago (Belleville, Ontario in Canada) whereas Stromberg Carlson was in Rochester, New York (Toronto, Ontario in Canada). I don't think Setchell Carlson set were ever marketed in Canada, and they don't seem to have been as prolific in terms of models, or production, as either Stromberg-Carlson nor Stewart Warner. Stewart Warner used to manufacture speedometers and other dashboard instruments for cars, and even manufactured grease guns for a time, so car enthusiasts are familiar with the company, some are even surprised to find out that they got involved in the radio and TV business.
Regards
Arran

[captainclock1988]

Well what makes me confuse all of those companies is that all three of those companies (Setchell-Carlson, Stromberg-Carlson, and Stewart-Warner) is that they all start with an "S" and so when you have 3 companies that are two name companies that are Hyphenated (or can be hyphenated depending on how they chose to write out the names) then it can be very confusing.

[captainclock1988]

I have a question about this radio, is there anyone that has access to this radio that has an intact unmolested speaker that they can take a picture of for me or has a wiring diagram for the speaker on this radio? I'm asking because while I have access to an original Rider's service manual for this radio, it doesn't list resistance measurements or give wiring diagrams for things like the speaker, the power transformer or IF and RF Coils and it would be nice to have wiring diagrams for those, especially the speaker, because I think the speaker was miswired at one point in time and I want to be able to see a wiring diagram or a picture of an unaltered speaker in one of these radios so I can confirm if the speaker in this radio was miswired or not.

Thanks for your help

[MrFixr55]

Hi Cap'n Clock,

Unfortunately, I do not have this radio.  This is a shame because this should be a good performer.  2A5s are the same as 42s (6F6s) except for filament voltages.  at 7 watts audio and an 8" or 10" speaker, this set should have a big sound.  I always recommend adding an aux input to radios like these so period music can be played from a computer or MP3 player with better fidelity than through an AM transmitter.

Attached below are sections of the schematic.  The first one is the complete audio and power supply section.
   

The next is a blow up of the speaker connections.
   
Examine your radio chassis, topside and underside.  Where is the output transformer?  Schematics will correctly indicate the radio's circuit but not necessarily the location.  From the above section of the Rider's Schematic that I obtained from Nostalgia Air, it appears that the
output transformer should be on the chassis or on the underside of the chassis. You will need to inspect your radio chassis and speaker to locate the output transformer. It does not appear that the transformer is on the speaker based on your picture.  The speaker looks like a period-correct speaker but may or may not be the original.  Different manufacturers use different field coil impedances.  Some put the whole radio B+ load through the field coil.  Other do not put the output stage plate load through the field coil.  Almost all "electrodynamic" speakers (speakers with an electromagnet instead of a permanent magnet field) have a "hum bucking" coil.  this is wound along with the field coil and is wired in series with the voice coil with a polarity that should "buck" or cancel any hum not filtered out by the rest of the power supply design.
.
If the transformer is on the chassis (maybe the underside?), then there should be 4 leads to the speaker.  2 of these leads (white and green) are for the field coil.  The other 2 red and yellow) are for the speaker voice coil.  Between the rectifier filament (white wire) and the output tube screens (green wire) there should be about 460 Ohms.  Between the speaker voice coil (and hum bucking coil in series with it) the resistance should be very low.  Because the speaker voice coil / hum bucking coil is in parallel with output transformer secondary, the connection must be disconnected to correctly measure the voice coil.

If 2 of these speaker leads go directly to the output tube plate connections, then your speaker is likely incorrect as only "magnetic" speakers have a direct connection to the output stage without a transformer.  In the 1930s, magnetic speakers were used only on battery powered radios.

Hope this helps.

[captainclock1988]

Hi Cap'n Clock,

Unfortunately, I do not have this radio.  This is a shame because this should be a good performer.  2A5s are the same as 42s (6F6s) except for filament voltages.  at 7 watts audio and an 8" or 10" speaker, this set should have a big sound.  I always recommend adding an aux input to radios like these so period music can be played from a computer or MP3 player with better fidelity than through an AM transmitter.

Attached below are sections of the schematic.  The first one is the complete audio and power supply section.
[Image: https://philcoradio.com/phorum/attachment.php?aid=31256]   

The next is a blow up of the speaker connections.
[Image: https://philcoradio.com/phorum/attachment.php?aid=31257]   
Examine your radio chassis, topside and underside.  Where is the output transformer?  Schematics will correctly indicate the radio's circuit but not necessarily the location.  From the above section of the Rider's Schematic that I obtained from Nostalgia Air, it appears that the
output transformer should be on the chassis or on the underside of the chassis. You will need to inspect your radio chassis and speaker to locate the output transformer. It does not appear that the transformer is on the speaker based on your picture.  The speaker looks like a period-correct speaker but may or may not be the original.  Different manufacturers use different field coil impedances.  Some put the whole radio B+ load through the field coil.  Other do not put the output stage plate load through the field coil.  Almost all "electrodynamic" speakers (speakers with an electromagnet instead of a permanent magnet field) have a "hum bucking" coil.  this is wound along with the field coil and is wired in series with the voice coil with a polarity that should "buck" or cancel any hum not filtered out by the rest of the power supply design.
.
If the transformer is on the chassis (maybe the underside?), then there should be 4 leads to the speaker.  2 of these leads (white and green) are for the field coil.  The other 2 red and yellow) are for the speaker voice coil.  Between the rectifier filament (white wire) and the output tube screens (green wire) there should be about 460 Ohms.  Between the speaker voice coil (and hum bucking coil in series with it) the resistance should be very low.  Because the speaker voice coil / hum bucking coil is in parallel with output transformer secondary, the connection must be disconnected to correctly measure the voice coil.

If 2 of these speaker leads go directly to the output tube plate connections, then your speaker is likely incorrect as only "magnetic" speakers have a direct connection to the output stage without a transformer.  In the 1930s, magnetic speakers were used only on battery powered radios.

Hope this helps.

Yes that was very helpful, I had the original Rider's Book that had the service data but the schematic they had in there for this radio didn't have a very detailed drawing of the audio section of this radio, just an illustration in the schematic showing the various connections to the speaker but no labels showing what connections was what and where each connection went to.

The way the speaker that is in this radio was wired up is that there was a bare copper wire coming from the back of the speaker (I'm assuming that would of been the humbucking coil) that was covered with spaghetti tubing that one of the wires that looked like that was connected directly to the voice coil connection and the other one was connected to one of the wire leads coming out of the radio chassis (I'm not sure which color it was though because the wire insulation is so badly faded that the color is hard to make out) but the way it was connected didn't look quite right, and then one of the other wire leads coming out of the chassis for the speaker was connected to the other voice coil connection but no humbucking coil connection to the other voice coil connection. The other two wires coming from the chassis was going to the field coil, which didn't seem quite right, but I could be wrong which is why I wanted to see a well marked circuit diagram of the speaker connections to confirm whether or not it was wired up correctly or not.

Is it possible that if the previous owner of this radio (or one of the previous owners of this radio) did indeed replace the original speaker in this radio with an "aftermarket" speaker that they may have wired it up in a way that it would work with that particular speaker (which would of been a little different from how the original speaker would of been wired up) and that's why it looked off to me as far as how it was wired up? Because perhaps this speaker wasn't a true electrodynamic speaker but perhaps a modified PM speaker?
I'm asking because this speaker has no makers marks or any other identification marks on it except for a number that is rubber stamped in white ink on the speaker cone and that's it, no serial numbers, no model numbers, no brand name markings or anything, and the cover that goes over the field coil/Hum-bucking coil area doesn't look factory to me, it looks like it was added onto the speaker.