[sdiy] Preventing Radio Ham Interference

[Gordonjcp]

On Mon, Nov 28, 2016 at 04:14:26PM +0000, Oakley Sound wrote:
> 
> When transmission is ongoing I hear what seems to be a loud buzz at
> 100Hz and harmonics. It's as if the mains is being gated into the
> audio pathway during transmission. The higher the RF output power
> the louder the buzz. The Event monitors pick up the noise even with
> the audio cables unplugged and the mains additionally filtered.
> Bizarrely it also makes the modular and my old SY-1 go out tune but
> I can't detect any drop in power supply voltage so I think it's
> directly affecting the VCO circuitry.

That's generally what happens - the RF is picked up by other equipment and "detected" by nonlinearity in it.  There's only so much that sticking ferrites on the power leads will do.  Unfortunately in many cases about all you can do is pick times to transmit when you're not recording, and pick times to record when he's not transmitting :-)

IIRC you're in the UK?  If you ask Ofcom they will probably charge a fortune to come out and suggest you add a bit more shielding and try and co-ordinate your hobbies, but it might be worth trying to get hold of one of the local field guys and see what they suggest.  I might be able to put you in touch with someone in Peterborough, but he might know someone closer.  The Scottish guys all seem to be based around the North-East.

-- 
Gordonjcp MM0YEQ