model 20 hum (detector circuit?)

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model 20 hum (detector circuit?)

OZ4
Senior Member

Posts: 285
Threads: 27
Joined: Nov 2012
City: Tehachapi. California

#5

10-20-2015, 09:01 AM

I would try poking around the grids with a .1uf cap to ground to localize the source of the hum. The cap will ground out any signal without messing up the bias. Make sure voltage rating is high enough. An oscilloscope would help here too. And don't forget to check the tube sockets for bad connections.

!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!
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     [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif] Chris

(This post was last modified: 10-20-2015, 09:04 AM by OZ4.)

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model 20 hum (detector circuit?) - by Tubesforme - 10-19-2015, 12:11 PM

RE: model 20 hum (detector circuit?) - by Steve Davis - 10-19-2015, 02:40 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-19-2015, 05:23 PM

RE: model 20 hum (detector circuit?) - by Steve Davis - 10-19-2015, 06:03 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-20-2015, 09:01 AM

RE: model 20 hum (detector circuit?) - by mikethedruid - 10-24-2015, 06:04 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-24-2015, 08:24 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-27-2015, 02:58 PM

RE: model 20 hum (detector circuit?) - by Alan Douglas - 10-24-2015, 06:23 PM

RE: model 20 hum (detector circuit?) - by mikethedruid - 10-24-2015, 10:48 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-29-2015, 05:21 PM

RE: model 20 hum (detector circuit?) - by Steve Davis - 10-24-2015, 11:01 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-24-2015, 11:46 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-28-2015, 07:14 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-30-2015, 06:30 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-25-2015, 09:57 AM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-25-2015, 11:40 AM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-25-2015, 10:39 AM

RE: model 20 hum (detector circuit?) - by Kenneth F. Besso Jr. - 10-25-2015, 07:01 PM

RE: model 20 hum (detector circuit?) - by morzh - 10-25-2015, 10:08 PM

RE: model 20 hum (detector circuit?) - by Steve Davis - 10-26-2015, 07:38 AM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-26-2015, 09:18 AM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-26-2015, 11:14 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-26-2015, 09:34 AM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-26-2015, 10:24 AM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-26-2015, 11:12 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-27-2015, 07:43 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-27-2015, 10:38 PM

RE: model 20 hum (detector circuit?) - by Steve Davis - 10-27-2015, 11:25 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-28-2015, 12:12 PM

RE: model 20 hum (detector circuit?) - by Ron Ramirez - 10-28-2015, 01:34 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-28-2015, 07:07 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-28-2015, 10:52 AM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-28-2015, 12:08 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-29-2015, 06:50 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-28-2015, 02:36 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-28-2015, 07:03 PM

RE: model 20 hum (detector circuit?) - by Ron Ramirez - 10-28-2015, 08:10 PM

RE: model 20 hum (detector circuit?) - by radiohenry - 10-29-2015, 06:31 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-29-2015, 06:44 PM

RE: model 20 hum (detector circuit?) - by LASJayhawk - 10-29-2015, 06:57 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-29-2015, 09:10 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-30-2015, 06:21 PM

RE: model 20 hum (detector circuit?) - by LASJayhawk - 10-29-2015, 09:36 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-30-2015, 12:28 PM

RE: model 20 hum (detector circuit?) - by LASJayhawk - 10-30-2015, 02:29 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-30-2015, 02:34 PM

RE: model 20 hum (detector circuit?) - by klondike98 - 10-30-2015, 03:24 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-30-2015, 05:13 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-30-2015, 06:04 PM

RE: model 20 hum (detector circuit?) - by OZ4 - 10-31-2015, 09:40 AM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-31-2015, 01:06 PM

RE: model 20 hum (detector circuit?) - by Ron Ramirez - 11-08-2015, 09:28 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 11-09-2015, 07:11 PM

RE: Low continual hum in model 21 - by Steve Davis - 10-23-2015, 09:34 PM

RE: Low continual hum in model 21 - by Tubesforme - 10-23-2015, 10:19 PM

RE: Low continual hum in model 21 - by Steve Davis - 10-23-2015, 11:01 PM

RE: model 20 hum (detector circuit?) - by Tubesforme - 10-24-2015, 05:50 PM

Need correct voltages for det and af model 20 - by Tubesforme - 11-07-2015, 04:54 PM

RE: Need correct voltages for det and af model 20 - by morzh - 11-08-2015, 11:09 AM

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