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1920's 5/6 tube trf's - Printable Version

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1920's 5/6 tube trf's - tab10672 - 08-09-2013

Is it possible to replace the tube lineup in the old battery sets from 01a's to another tube, say 30's or 99's by changing/supplying the repacement tubes fil. and plate voltage?

RE: 1920's 5/6 tube trf's - BrendaAnnD - 08-09-2013

I've done similar refits before (long, long ago). There isn't much component tweaking that even CAN be done. You would want to look up the tube characteristics and make sure the plate load is appropriate, or your interstage transformers won't work well.

RE: 1920's 5/6 tube trf's - Ron Ramirez - 08-09-2013

If your sets have UX (plug-in) sockets, then you should be able to use 30 tubes by reducing filament voltage to 2 volts. Your filament rheostats won't work as designed, though.

In the past, before people discovered that the 1G4 could be used as an 01A substitute and the price of 1G4 tubes went up accordingly, I made up several adapters using old bases of four-pin tubes (with the bayonet pin) and an octal socket on top to use 1G4 tubes in sets like the Freshman Masterpiece. Other than not being able to control volume with the filament rheostats, the subs worked fine. Again, filament voltage has to be lowered to an appropriate level.

RE: 1920's 5/6 tube trf's - Arran - 08-09-2013

You can also use 1Q5s as a substitute from WD11s, if they are rewired as a triode, I think there are similar subs you can use for 199s. I don't understand why people think they can only use newer triodes as substitutes for older triodes, why pay extra money for having two fewer grids? When it comes to 201As I can't see the point in using subs unless you happen to have a lot of a given newer tube on hand, if you can't find the globe versions you can always use the ST style ones. I can't see any advantage in substituting a 201A for a 199, 199s are much less common then '01As, probably because RCA brand sets (G.E and Westinghouse) were the primary users of 199s, there may have been others but not many.
Regards
Arran

RE: 1920's 5/6 tube trf's - tab10672 - 08-09-2013

Thanks for the responses, the reason i asked is i recently bought a large lot of tubes that was full of 99's and globe 30's and having used them in single and 2 tube home brew sets before as an 01A sub I thought maybe i could fill up some of the batt. Radio's i have. Thanks again, Todd

RE: 1920's 5/6 tube trf's - Arran - 08-10-2013

I think that the 199s are 3 volts, the 30s are 2 volts, but the 201As are 5 volts at .25 amps each. I would save the 199s for an RCA set that uses them but the types 30s make perfect sense to use as a 201A substitute, however the filament current and of course the voltage is different so the original rheostat/volume control setup in a 201A equipped set won't work.
Regards
Arran

RE: 1920's 5/6 tube trf's - Alan Douglas - 08-15-2013

I expect you could trade 01As for 99s two-for-one, providing the 99s have good emission.