On Tue, 3 Jun 2008, Count Floyd wrote:

I have heard that there are very few electrolytic capacitors in this
machine, as most of them are ceramic disk. The only ones are in a can
on the chassis. If the radio is working well as original, would it be
better to just leave well enough alone? I always try to live by the
maxim: If it ain't broke.....
Thanks,

Of course, there were never many electrolytic capacitors in tube
equipment. In the power supply, and bypassing the cathodes of the
audio stages, and maybe at some point to bypass the B+ line close
to the audio output stage.

They weren't common because they weren't needed. Since tubes are
high impedance, large value capacitors weren't needed much, and
hence no shift to electrolytics.

Solid state equipment uses a whole lot more electrolytics because
of their low impedance operation, so you need large value capacitors
for coupling and bypassing. Electrolytics are the only reasonable
way to get those larger values.

All the talk of recapping old radios is basically due to old capacitors.
Badly designed capacitors at the time, or simply the best at the time,
end up aging badly. The capacitors were fine at the time, it's just
few gave much thought to the equipment being used decades past their
prime. So decades later, those low value capacitors often need replacing
because they just don't work properly nowadays. So you get bad bypassing
at RF, and you get weak or non-existent audio because the coupling
capacitors have gone.

Replacing an electrolytic in the power supply is hardly "recapping", it's
repair. "Recapping" is when someone feels they should replace all
the capacitors, or actually needs to replace a specific capacitor. And
then once you've done one, it often makes sense to do the whole lot,
especially if it requires a complicated disassembly. IN some cases
capacitors known to go bad over the decades were used, so it's worth
replacing all of them because they will go bad eventually, or enough
have gone bad that it's hard to get a handle on where the exact problem
lies, and replacing the capacitors gets that variable out of the way.

Michael VE2BVW