[sdiy] Preventing Radio Ham Interference

Mike HEQX mike at heqx.com
Tue Nov 29 15:23:04 CET 2016

I like the idea of an earth grounded mesh on the wall behind the 
recording rig. It can't hurt even on a good day. This lath screen is 
what comes to mind.


On 11/29/2016 4:55 AM, Oakley Sound wrote:
> Wow. Thank you for all the replies and help. I got several PMs too and 
> even a phone call.
> To answer a few questions:
> I have done the ferrite clamps and they seem to work on the hi-fi when 
> added to the speaker and main cables. But I have yet to test this when 
> he is outputting at full power.
> 20W causes a noticeable buzz on the Event monitors in my music area 
> even with the audio cables unplugged and ferrites on the mains cable. 
> At 60W then the buzz is so loud it's unusable and VCOs go out of tune. 
> 60W is the maximum power output of his rig. I've no idea how much ERP 
> is being developed.
> I've not asked him to see what happens when the antenna is pointed in 
> any other direction. But when he was doing the tests it was around 45 
> degrees away from pointing directly at my house wall. Getting him to 
> test it with a dummy load sounds a good idea - although it should be 
> noted that the same rig driving a different but omnidirectional 
> antenna causes no problems.
> We do share the same power and phase. The substation (step down 
> transformer) is up a pole just outside my back garden and I'm the 
> closest in the village to it. When pointing at my house his antenna is 
> also pointing straight at the overhead power lines that feed my house.
> I will look into adding some capacitance across the bridge rectifier 
> diodes of the modular power supply.
> His hi-fi is unaffected by it although it's more modern and the beam 
> was not pointed across his house at the time of testing.
> His antenna is probably about as high as it can go on a single 
> unsupported pole. We're both in bungalows and the antenna is about as 
> high as the apex of his roof.
> With the exception of the modular and the Event monitors everything 
> that is affected is old and was built before the letters EMC meant 
> anything. The Events are also liable to picking up mobile phone 
> interference so I think it may be worthwhile getting some more 'rad 
> hard' replacements for these.
> I may try some grounded chicken wire to create a shield but from 
> various answers it seems that this may have little if no effect unless 
> I go for the full cage which is impractical. However, that idea I had 
> of buying an old shipping container and converting it to a home studio 
> is starting to become more and more attractive.
> Tony
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