[UK-CONTEST] RF Feedback

[Cooper, Stewart]

In setting up my station for this year's CQ WW SSB I have discovered that my
constantly tripping Alpha 91 is caused by RF feedback getting into the Heil
mic. It's not a problem that is immediately obvious on my transmitted audio.
In fact, no one has ever mentioned anything, and it is worse on some bands
(10m) than others. What I need is some real world practical advice to
eliminate the problem. Perhaps that advice might help others with a similar
problem. I use a Heil ProSet headset with a DX Doubler, MFJ 432 DVK and
FT1000MP. Now, the DX Doubler doesn't appear to add to the problem and the
MFJ might appear to, but I run it on internal batteries and the problem
remains even when it's out of circuit. I use a ferrite toroid on the headset
mic cable before it enters the DX Doubler. I have tried earthing all the
components in the shack to the same earth 'bus' although this (for audio
equipment) might not be a good idea. Any other suggestions?
Mail me direct if you feel this is not contest related enough. Response may
be slow. I'm /5B4.
73

Stewart Cooper 
GM4AFF/GM0F