Thank you gentlemen for your input.Yes same supply as radio and fan.Yes I see the problems with brushless fans.I bought several and now must experiment.The large caps worked to a point,now I will try ceramic caps. Ron
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--- In BITX20@..., arv <arvid.evans@...> wrote:
Ron
This being a "brushless" fan may provide insight into the problem. These
units
usually have an internal switch circuit that converts DC input into AC
for running
the no-brushes motor. Polarity switching noise may be the culprit.
<
>
< >
Some electrolytic capacitors have significant internal inductance and
thus may
not be the best thing to shunt HF signals to ground. A disk ceramic
capacitor
that has fairly low impedance at either RF or IF frequency may be more
effective
at minimizing interference from the fan. In difficult cases it may even be
necessary to design and build a band-stop filter to minimize the noise
problem.
Arv - K7HKL
_._
On 05/27/2013 03:38 PM, ronbaechle wrote:
Tried three 470 parallel caps still sum hum.This is 3200 rpm fan. Any
more ideas? Thanks Ron
--- In BITX20@... <mailto:BITX20%40yahoogroups.com>,
"ronbaechle" <ronbaechle@> wrote:
Tom I tried 100uf didn't work. I will try larger Thanks Ron
--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, Tom
Sevart <n2uhc@> wrote:
Bought a nice brushless silent geld fan,but was surprised to
hear all the huge
amount of noise in receiver. Best way to clear noise, Cap? What
size? Thanks all
techs Ron
I put a nice large electrolytic cap across the terminals for the
fan, but I don't remember how large it was. I think it was probably a
1000 uF or something. I don't think you'll go wrong with that size or
larger.
Tom Sevart N2UHC
St. Paul, KS
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