range hood wrote:
Hello all, I'm new to this forum. I may not even be in the correct forum
for a question like this, if anyone has a link for a better place for me
to go, I would appreciate it. I have acquired an old tube radio at a
garage sale. It just kind of looked at me and said "help me". I don't
have any experience rebuilding electronics, especially antique stuff. I
am handy with small parts and soldering. The radio is a Deforest Crosley
built in 1937 and is a battery operated model. I don't really know what
a B+ 135 volt battery looks like, I've never heard of anything like
that. Is it possible to use a transformer to convert AC to what I need?
I have ordered the wiring diagram, but don't have it yet. I am aware of
issues with old electrolytic capacitors, some of the threads I have
have read in this forum have made it apparent that they may have to go
in favor of modern ones. That is OK with me, I'm not too concerned with
keeping it all original, I just want it to work. If anyone has general
advice for me for a project like this, please feel free to respond.
Thanks. Norm




Regarding the batteries, one of your replies was right on. It used 3
45v batteries in series for the B+. I doubt you'll have many
electrolytics in that set owing to the fact that its a battery set.
There may be one in the audio output cathode circuit. The schematic
will tell all, of course. The hardest part will be coming up with the
1.5v for the tube filaments, again assuming they are 1.5v tubes.
Fairchild has a nice and inexpensive ($3) TO-220 regulator package rated
at 4 amps. One can drive it from one half of a rectified, center tapped
6.3v transformer and/or half-wave rectifying the entire secondary. Its
a very cheap and easy way to get reliable 1.5v for those tubes. If the
tubes are 6v types, just half-wave rectify and filter the 6.3v winding.