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Re: [Amps] Alpha 76A - 120hz hum on 160m only

To: amps@contesting.com
Subject: Re: [Amps] Alpha 76A - 120hz hum on 160m only
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Thu, 17 Oct 2013 08:31:12 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
On 10/17/2013 6:22 AM, TexasRF@aol.com wrote:
Jim, it is possible that the hum is present only in your local receiver and
  not actually being transmitted.
As a test, you might have a local listen to the signal and give you a
report.

That's good advice. The RF may be getting into your RX via a Pin One Problem on audio or control leads. Hum is a common symptom of a gain stage going non-linear due to RFI. There's a discussion of "The Pin One Problem" in http://k9yc.com\RFI-Ham.pdf and in several other tutorials on http://k9yc.com/publish.htm in the section on audio.

73, Jim K9YC
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