[hpsdr] Pennywhistle bias control failure

[Sheldon Hands]

I chased my tail on a similar Mic audio fault, it turned out the real 
culprit was the external powered speakers.
I use a cheap skype headset but fitted a 1nF right accross the mic 
insert and four or five turns on a ferrite ring at the Atlas enlosure entry.
Shel CT1IZU

On 15/05/2010 09:40, Chris Smith wrote:
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> Another problem I'm having is RF getting back into the mic input on 20M and above. I made a (grounded) metal plate with sockets for phones, keyer&  mic/PTT so that I could locate all these conveniently away from Pandora. Despite using screened lead for the mic I can't prevent RF getting into the mic input. Strangely this doesn't appear on the phones when I select MON on PowerSDR. I'm thinking of going back to a direct mic connection to Penny and bypassing my plate. Anyone got any ideas?
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> BTW is there an optimum impedance for the mic? I had been using a cheap headset with electret boom mic and this worked OK on all bands. Since relocating all sockets to my plate and rejumpering Penny to remove electret bias, I'm using a moving coil mic with 200 ohm impedance.
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> Cheers&  73
>
> Chris G4NUX
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