[hpsdr] Pennywhistle bias control failure

[Chris Smith]

John

I'm not absolutely sure about the RF feedback but the symptoms are that on 20M and above, although I'm apparently (from reports) generating a strong signal, the audio is very distorted. I borrowed  an FT817 from G4EFO and monitored my signal and can confirm that this is the case. This only started happening after I went from an electret mic to a moving coil mic - both on booms from a headset - plus the inclusion of an extra connector at the metal plate.

In the past distorted audio has usually been because of a) overdriven modulator or b) RF feedback.  The distortion seems to occur at even moderate mic gain settings so I assumed b). Remember this doesn't occur on 80M or 40M.

Cheers & 73

Chris G4NUX


On 16 May 2010, at 06:39, John Petrich wrote:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> Chris,
> 
> You posted that you were getting RF back into the mic input.  What are your symptoms?  What makes you so sure that RF is feeding back to cause the symptoms?
> 
> Regards,
> 
> John Petrich, W7FU 
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