Rod,
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. Being an EMC engineer, I was very
wary of having a switcher in my station (I operate 160m thru 70 cm, so
that's a lot of spectrum that could get messed up). If the Astron
switcher is creating RFI, I am guessing that something has gone wrong with
the internal circuits and you would probably do best to contact Astron.
Now, if your power supply is one of their very reliable linear series
(which weigh a proverbial "ton"), then I can just about guarantee that
something has gone wrong with the internal voltage regulator that drives
those big pass transistors on the back of the supply. It is not uncommon
for linear regulators to "take off" and oscillate, creating sometimes
extensive RFI. Sometimes the chip itself is bad, and other times the
problem can happen either because no by-pass cap was used at the input
side of the regulator or the cap is there but went bad. Again, contact
Astron.
Either way, I would hope that with only 20 hours of use that the supply is
still within the 1 year warranty. If not, you'll still do best (in my
opinion) to contact Astron and return it. Trouble shooting either power
supply will involve use of a decent oscilloscope (having at least 50 MHz
bandwidth) and/or a spectrum analyzer. Either instrument should allow you
to find the problem within minutes.
It would be helpful if you were to post which model Astron you have.
73, Dale
WA9ENA
rrath@charter.net
Sent by: rfi-bounces@contesting.com
05/24/2007 11:30 PM
To
rfi@contesting.com
cc
Subject
[RFI] RFI from Astron power supply
Hello to the list. I have a 35 amp Astron power supply that is giving of
RFI.
This p.s. has had less than 20 hrs use. I am charge of the Ham radios for
our EOC, where we use this p.s. I just had the local power company RFI guy
come and we located 9 power poles that are giving off RFI as well as the
p.s. They will take care of the poles, I need to take care of the p.s.
Any help on what to do to get ride of the RFI from the 35 amp power
supply?
The p.s. is giving off about an s-5 to s-7 RFI.
Thank you for any help you can give.
Rod KC7VQR
W7SCC Trustee
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