> I presume that the Astron supply in question is the SS-35
> or SS-35M. Those
> are switching power supplies, but are among the best I
> have ever seen
> regarding RFI to HF or other radios. I have been using an
> SS-35M for more
> than 3 years now and think it is great.
RFI is like describing pain, every station has a different
tolerance for RFI just like every person has a different
tolerance for pain.
At my station http://www.w8ji.com/station_ground.htm:
1.) feedlines all have very solid connections on the
shields and all enter through a bulkhead
2.) antennas are properly fed and decoupled for common mode
currents
3.) antennas are a long distance from the shack
Because of this I can use a pretty ratty power supply and
not have RFI.
The very same supply in my mobile where the antenna is only
ten feet from the supply or at another person's house is
absolute trash.
Most of the severe RFI problems I've seen come as much from
shack wiring and poor antenna implementation as from the
supply itself.
It takes two to tango. Not only must the supply radiate (and
the Astron switchers certainly do that!); the antenna system
or equipment must somehow be letting the noise in. The nice
thing about looking at the antenna system and feedlines is
any problems cured there make every work better. This is
where we pay the price for dipoles without baluns or with
poor baluns, poor cable shield connections and entrance
grounding, verticals with no ground or a mediocre ground,
and other similar things.
73 Tom
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