A question about vacuum tubes

["A. Joseph Ross" <lawyer@attorneyross.com>]

I'm sure there are some people around here old enough to be familiar with 
how tube sets work.  I have an old Zenith AM-FM radio with a rather nice 
sound, but it's had some problems lately.  I diagnosed the problem as the 
audio output tube, which is 35C5.  I had an old 50C5 tube, which was used 
for the same purpose in AM-only radios, I substituted it, and it works 
well (I seem to remember something about it being sort of OK to do that 
if the substituted tube had a higher voltage, as represented by the 
initial number.).  My question is whether there's any harm to the radio 
in leaving it that way, or whether I really ought to look for a 35C5 from 
somewhere.

-- 
A. Joseph Ross, J.D.                           617.367.0468
 15 Court Square, Suite 210                 lawyer@attorneyross.com
Boston, MA 02108-2503           	         http://www.attorneyross.com