On Fri, 14 Jul 2006 08:29:52 -0700, W7RY wrote:
>We have been finding issues using switching power supplies on
>commercial 2-way radio base stations and repeaters.
Interesting. To have an intelligent discussion of this, I think we
need to understand that switchers can be made with any range of
performance spec for RFI from very good to awful. Because I don't
have a handle on which are good and bad, I've always stuck with
linear regulators.
So perhaps we ought be begin this discussion by looking at the
make, model, and performance specs of those supplies that were
problematic.
We should also look at the mechanism(s) by which the interference
was coupled. For example, was it riding on the DC and getting past
poor filtering on the radio's power leads, was it radiated by
interconnect wiring as common mode and picked up on the antenna,
was it radiated by the AC power line and picked up on the antenna?
What was the spectrum of the trash that the switcher generated? Was
it baseband (that is, audio and harmonics) and it caused the radio
to generate transmit or receive spurs? Or was it up at 450 MHz?
Depending on the answer to these questions, there may or may not be
easy fixes.
73,
Jim Brown K9YC
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