[1000mp] Cooling fan causes buzz in transmit audio on Mark V

Fri, 25 Oct 2002 09:24:16 -0400

That's possible Pete.  An on-air report said it sounded electrical
rather than acoustical but it will be easy enough for me to check
once I get the rig back together.  Right now the rig is partially
disassembled while I install the Inrad key click mod.

Thanks,
Ed
W2UV

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Pete Smith
Sent: Friday, October 25, 2002 9:08 AM
To: [email protected]
Subject: Re: [1000mp] Cooling fan causes buzz in transmit audio on Mark
V

At 08:56 AM 10/25/02 -0400, you wrote:
>It looks like whenever the cooling fan in my Mark V runs, it
>causes a buzz in the transmit audio.  It happens with a MD-100
>and Heil Goldline.  The only connections to the radio are:
>Antenna, mike, external speaker and earth ground.  Does anyone
>else have this problem and/or a fix?  Just starting to trace out
>the fan circuitry in the service manual to see if some by-pass
>caps or shielding of the fan wires might be needed.

This may be too easy, but is it possible that you're running too much
compression?  My Mark 5 fan makes quite a lot of acoustic noise, and it
isn't hard to imagine a microphone picking it up if the gain were high
enough.

73, Pete N4ZR
Sometimes a tower is just a tower

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