dgsvetan@rockwellcollins.com wrote:
> Deni,
>
> The fact remains that you could spend a lot of time applying ferrites
> and
> by-pass caps, as well as line filters, to many computers and related
> gadgets, and still have moderate to severe RFI to your ham gear from
> this
> other equipment. (Keep in mind that the majority of readily available
> ferrite cores and beads are designed for maximum effectiveness in the
> VHF
> region. You can get ferrite mixes that work well at HF, but you
> usually
> need to find a vendor and order them.) One approach that almost
> always
> works is to REPLACE the blasted switcher power supplies with linear
> ones.
> This is probably easiest to do with wall warts. Simply measure the
> output
> voltages (and take note of the current rating) from an offending wall
> wart
> supply (such as the one for your printer), and either buy or build a
> linear
> replacement.
Hi Dale, and all who have given advice and comments, many thanks.
One thing is clear I am not alone with this nuisance and my experiences are
in line with others.
I agree, having tried ferrites on numerous things they often don't work as
expected probably because of unsuitable/unknown type. I am trying to source
some type 43 and type 77 in EU.
I've resorted to running my Toshiba laptop (15v @3A) from a linear
PSU, although the laptop switched mode supply is, or would, be ideal for
powering/charging my K2 but as it is so noisy I don't use it.
The main PC is in a metal tower type case and is a homebrew, built about 2
years ago using good components, (but not neccessarillry best from an RFI
point of view, I know) The main problem is the CRT monitor as
usual, and I sometimes do switch it off if the birdies are causing trouble
on a signal, seems quite a number of people resort to the "switch off "
method!
I know the usual tricks of changing the screen resolution etc but this just
moves the mess to some other band/ frequency.
One day I hope to have a quiet monitor but it will no doubt be the newer
technology and not CRT, in the meantime I will try to reduce my RFI sources
around the shack.
Thanks to all for comments, great group.
73, Deni
F5VJC, GM3SKN
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