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Seeking advices on eliminating noise on a Philco 70-A
AI2V
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Posts: 201
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Joined: Dec 2005
City: Morris Plains, NJ
#2

01-13-2006, 12:40 PM
It depends what the noise sounds like- static crashes are often a bad tube.

I would first check the cathode bias resistor, #27- the 50K. If the bias on the AM detector is too low all sorts of noise will pass through.

The screen grid cap #31- .09 must stay in the circuit- it keeps the audio, RF, and IF signals from crosstalking to other tubes.

My only problem with the 70 is the audio distortion at higher audio levels; next time I'll buy a 90!. Good troubleshooting......
Pete AI2V
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Noise in the 70 detector - by AI2V - 01-13-2006, 12:40 PM
[No subject] - by Guest - 01-13-2006, 03:08 PM
[No subject] - by PTurney - 01-13-2006, 07:20 PM
[No subject] - by Guest - 01-14-2006, 09:41 AM
[No subject] - by Guest - 01-24-2006, 05:53 PM



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