In article "Wern" wrote:

Thanks for reading this message.
Setup: Catamaran 45'
ICOM M802 with AT140 tuner, professionally installed, sidestay ant
portside
Battery Charger/Inverter Mastervolt Dakar Sinus Combi, located in engine
room s/board side.

My problem, if the Battery charger/Inverter is on, which it normaly is a
carrier every 20khz (+ -) with a 60hz humm is audible over the whole HF
spectrum. Quite strong so that weak stations are not readable. The noise
is picked up via the arial not thru the DC supply. If I disconnect the ant
the noise is gone. But just having the ant tuner connected with no ant,
the noise is audible.
I am looking fwd to some ideas how to get rid of the interference
thanks and rgds
Wern


There are a FEW, tricks that you mght try, but the MAIN thing you will
find IS:

1. Any type of Switching Powersupply is going to produce wideband RF
noise across the MF/HF Radio Spectrum. Battery Chargers, Computer
Power Converters, DC Motor Brushes, a whole range of things cause
this problem.
2. Most ALL the OEM's of such equipment do NOT certify their stuff
for RF Noise output, and don't use this criteria as a design
parameter.
3. ReEngineering other peoples stuff is a PAIN in the Posterior.
4. Very few Mariners actually use MF/HF Radios in the Commercial
Services, these days, compared with Days gone bye, in the 60's
thru the 80's.
5. If you want to make it work, you have to either pay an OLD
Marine Radioman, a lot of money, to come fix it for you, or
learn to become an OLD Marine Radioman, and spent a little less
money to fix your problem. It is NOT, going to be cheap....

Bruce in alaska
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