[JRomero]

Hellow from Spain

Some body knows something about this small ac/dc tombstone under license RCA?
I fixed it and it’s working but i’m looking for the schematic to understad what kind of circuit it is (and how it works).

Some info and photos:

[Image: http://thumbs.subefotos.com/cd805be12a22...ce2d1o.jpg] [Image: http://thumbs.subefotos.com/9b3e71f3593a...31b52o.jpg] [Image: http://thumbs.subefotos.com/a072bcf6564f...4fffbo.jpg]

[Image: http://thumbs.subefotos.com/8162cf50a9c0...42fa8o.jpg] [Image: http://thumbs.subefotos.com/bd5474d683f0...34d0bo.jpg] [Image: http://thumbs.subefotos.com/0a0fd59a3401...29583o.jpg]

[Image: http://thumbs.subefotos.com/53003dcf68f2...871d2o.jpg] [Image: http://thumbs.subefotos.com/fb741d1e84c0...54d10o.jpg] [Image: http://thumbs.subefotos.com/e570c6e8260e...689b3o.jpg]

[Image: http://thumbs.subefotos.com/d6a4fc5d0c90...71f63o.jpg]



Broadcast and Long Wave bands.
three-section tuning condenser.
Paper "CuB" capacitors.
Tube line-up is 25Z5, 43, 77, 78, 6A7 and a 6,3V 0,3A bulb on the scale dial.
Electrodynamic speaker.
It had a resistance line cord, replaced time ago with a non polarized capacitor.

I think it is an RCA’s kit, or at least the circuit.
There isn't any paper label into the cabinet.
“Licensed under patents of the Radio Corporation of America and Associated Companies, only for radio amateur, experimental and broadcast reception … Serial number 64256. Made in U.S.A.”

It is a very strange radio to me.
Before i started to fix it, i thougth it was a classic superhet but it seems to have only one I.F. transformer (No Second I.F. transformer under or above the chassis, i think).
On the top of the chasis there is a little unshielded transformer conneted to the 77…
There are two trimmers near the band selector (well).
One padder at the chassis’s back (well).
Only one trimmer in the chassis’s back asociated to the little unshielded transformer conneted to the 77…
Ah! It haven't AVC circuit, at 02:00 A.M. strong stations are a problem

Some times i think this radio is something like an “AC/DC 84B” with an RF amplifier stage  

Thank you very much  

[Arran]

The second If transformer is that coil, mounted sideways, on top of the chassis, it is a superhet just a cheap one, the third section in the tuning capacitor is either unused or used for a preselector circuit, not for a tuned RF amplifier stage, I have a Sears Silvertone set like this. If it has a preselector circuit this may explain why they decided to use a second IF transformer with no can and only one trimmer, although it does seem silly to do that. It isn't an RCA, I don't know what it is exactly, it has a control layout similar to some Belmont radios, but more then likely it was made by one of the independent radio manufacturers in the Chicago area.
Regards
Arran

[Radioroslyn]

+1
>Licensed under patents of the Radio Corporation of America and Associated Companies
Just means that RCA was paid for the uses of some proprietary information or circuit used it this set. Doesn't mean that RCA had any other connection w/it. 
>Tube line-up is 25Z5, 43, 77, 78, 6A7
Not enough tubes to have a rf amp. 6A7 mixer/osc, 78 IF amp, 77 detector,  43 audio output, and 25Z5 rectifier. The triple gang capacitor as Arran stated is used for a double tuned ant circuit or it's not connected.
The key to finding this set is the 77 tube, that's the only unusual thing about the tube lineup. A more popular lineup would have a 75 rather than the 77. Short of that it's very common.

GL

[JRomero]

Thanks Arran and Radioroslyn

Tomorrow i'll check the gang condenser.

[JRomero]

[Image: http://thumbs.subefotos.com/dd0bbfb99fd2...4b849o.jpg]

I have been taken notes about the circuit, not drawing the schematic.
Still I have my eyes like two potatoes, trying to follow the circuit

[JRomero]

A while ago I modified the three gang condenser drawing, I drew it wrong

Well, Now I have something to understand this radio.
I found a few schematics with the same tube line-up (77 as detector) in "Rider's perpetual" thanks to the searcher of www.americanradiohistory.com.
Very strange line-up indeed, there are many more schemes with 75.

Not the same but very close:
Electric & Automotive Prod. Co. mod IL-55-LW and mod. IL-5.
https://www.americanradiohistory.com/hd2...8%206a7%22


Same line-up, they are similar but they have two gang capacitors:
Halson Radio mod 20B.
[Image: http://thumbs<br /><br />.subefotos.com/...defb3o.jpg]

Halson Radio mod 20B EUROPEAN.
[Image: http://thumbs<br /><br />.subefotos.com/...14343o.jpg]

Transformer Corp. of America (Clarion) mods. 422, 423, 425.
https://www.americanradiohistory.com/hd2...8%206a7%22

Remler Company, LTD. Mod: 26.
https://www.americanradiohistory.com/hd2...8%206a7%22

Federated Purchaser Mod: 8-A.
https://www.americanradiohistory.com/hd2...8%206a7%22

Regards

[Arran]

The Halson 20B European looks close (as well as being logical to find in Spain), as does that Electric and Automotive, model IL 55 AW, I was also looking for a three gang tuning cap, and a second IF transformer with a single trimmer on the schematics, as well as that tube lineup.
Regards
Arran