Fred McKenzie wrote:
In article GNhAf.141967$WH.127022@dukeread01, Kerry Miller
wrote:


Have any of you guys tried the new switching power supplies? I've seen
the one at Radio Shack (claims 25a but I doubt it), MFJ and Astron but
haven't ever used one. I normally just run 1 HF rig (max 100w) and a
small VHF rig (max 25w) for packet. Is a switcher solid and reliable
enough for something like that? I've considered getting something like
that and rebuilding the Astron when I can get the parts.


Kerry-

I have three switching supplies: One from Radio Shack, one from MFJ and
one from Icom (PS-125). They all work quite well as far as delivering
rated current.

The problem is that the high frequency switching noise can be picked up by
an HF receiver. The Radio Shack unit is TERRIBLE in this regard. The MFJ
is fairly good and the Icom is the best. Even so, the Icom switching
noise is picked up if it is anywhere near the antenna.

I'm currently using a makeshift indoor antenna consisting of a dipole made
of a pair of mobile whips on the second floor. Because of the noise
problem, I've gone back to using an old Kenwood linear supply with my Icom
756 Pro II. This radio has the band scope, so you can see the noise floor
increase across the band when the switching power supply is turned on.

73, Fred, K4DII
Thanks for the info. I picked up one of the RS supplies yesterday, and
you're right, it's pretty noisy on 80m, especially on my longwire which
terminates inside the shack. On 40m and above and on the outside
antenna (dipole or vertical) it's fine and below my noise floor. I
found a mod for it with some toroids and caps across the output to
filter it a little, I'll probably try that but it's workable for now
as-is since I don't work much 80m.

It will keep me on the air until I fix the Astron, I'll probably put the
Astron back on the HF rig and use the RS switching supply on VHF and UHF.

73,
Kerry
WD5ABC