[Collins] 6DF5 pin #7 not used in 75S3B?

Fri, 10 Jan 2003 13:49:00 -0600

HI DOCTOR JOHNSON. Re shielding, where can one get mumetal for that kind
of a shield?
jack..

On Fri, 10 Jan 2003 11:08:42 -0600 "Dr. Gerald N. Johnson, electrical
engineer" <[email protected]> writes:
> The tube grid is hooked to both 1 and 7. Doesn't matter which is 
> wired
> at the socket.
> 
> I found background AC hum in my 75S3B from hum modulating the noise
> through the mechanical filter. I added a magnetic shield to cure 
> that
> back about 1965. The other hum source was a little heater cathode
> leaking in the notch Q multiplier tube.
> 
> 73, Jerry, Technical Advisor to the CRA.
> 
> -- 
> Entire content copyright Dr. Gerald N. Johnson, electrical 
> engineer.
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> 
> 