[NJARC] Buzzzzzzzz

[Scott Roberts]

Hi Everybody!

Here's the latest issue I'm working with...

A Motorola Model 61A, AM radio. I've already recapped
& re-resistored it (I did not rewire this one! I'm
learning!!! lol)and there were a few previous "bodges"
put in by an earlier owner, which I cleaned up. One is
an electrolytic with 2 of the 40mfd lines running over
to one tube,(25Z5, at pins 3&4 cross link) the third
to another(6D6, at pin 3) and the ground a capacitor
going to ground at the on-off switch... Without this
cap, the radio plays nothing... There is also a switch
on the back panel which was added, I am not quite sure
of its function...

Anyway, it is receiving well- at 3am I was pulling in
WHAM 1180, Pittsburgh, WWVA 1170 Wheeling WVa, and
1140 WRBA Richmond, Va., among others. However, from
700 down, there is an ever present buzz, and a minor
hum throughout the whole range. Could this be due to
electrical interference, dirty tuning capacitor(I
spritzed with RS cleaner) etc.? Would my isolation
transformer reduce the possibility of electrical
interference?

Any ideas?

Thanks!
Scott


       
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