On 13/12/2015 09:04, Brian-Gaff wrote:
Two devices bought this week. Both work OK but the problem is that their
power supplies being of the switch mode kind push out lots of annoying RF
at frequencies between 100khz and around 20mhz. One of my hobbies is
listening to the short waves and even medium and long waves, so its all a
bit depressing to find that in order to continue both items need to be off.
One, the DVD has the psu inside its box and the on off switch does not
seemingly turn off the psu, which whines away at various places in the
spectrum, but the True Call cal screening device, although it works fine
puts out a nasty load of birdies quite close together which move as you do
various things on the unit or remotely, and have a 50 hz buzz on them for
good measure.
I may ask the company if they know of a source of old fashioned psus for it
as it has a very tiny right angled plug on the end of the wall wart wire.
Life is just getting very depressing when you consider how long we have
been making switch mode devices, surely we should expect better by now!
Brian

You could try putting ferrite chokes onto their PSU cables - it might
help a bit by preventing the RF having an aerial lead to radiate from.

http://www.maplin.co.uk/p/ferrite-clip-on-hem3012-n89ab

(Cheaper from proper components suppliers but MOQ applies)

--
Regards,
Martin Brown