Brian Alsop wrote:
Walwarts of the future will most likely be a real pain. I understand
some legislation has required all of them to be switching in the near
future.
I have a small halogen lamp which has a walwart that can be used as a
noise generator for adjusting the filters in my K2. It produces a
wideband hash that is perfect for this purpose. It is very loud in most
of the HF spectrum. I have never heard a switcher make a noise like
this; usually they make burbles, floaters, and digital tinkles.
Speaking of switchers, I once had an IC751 with a built-in AC supply, a
switcher which was mounted in a flat shielded box on the bottom of the
radio. There was a tinkling noise audible on all bands which drove me
crazy. This was some years ago, and it didn't occur to me that it might
be the power supply. I actually sent the radio to ICOM, and they 'fixed'
several things but the noise remained.
Although I know switchers can be quiet -- especially when you are
careful to use baluns, etc. on antennas to reduce local noise pickup --
I prefer an old heavy Astron linear supply in my shack.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
K2 no. 709
K3 no. 00007
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