[RFI] COMM0N MODE NOISE OBSERVATIONS AND REPAIRS
Dxhogg at aol.com
Dxhogg at aol.com
Sun Dec 26 09:57:19 EST 2004
i had posted about a week ago about common mode noise and what i had thought
was a really awesome "repair". well the repair really works but along the
road of determining what was really at play creating all the different noises i
have discovered all of the problems in the station was of poor
infrastructure. i had originally wired the operating position all station grounds and
interstation cabling about 18 years ago. well to put i in simple terms it was all
junk. wall warts, braided cable for grounds, and poor quality coax were the
real culprits.pay extra attention to ground loops.wall warts are a prime
cause of ground loops cut all the cables off the warts and use only the cable
and use a good quality 10 amp power supply for all the ancillary station
equipment. multiple antennas and feed lines should all be kept galvanically
separated from one another till the cables are connected at your main station
bulkhead what i mean by separated is don't use the ground for a 160m lnv l as a
tower ground
ect...look at your station layout in a ground loop aspect you will be amazed
at isolating these problems clean up the noise floor. i had a terrible noise
on 160m that seemed to follow the resonant FREQ of the transmit antenna when
i would disconnect the open wire feed from the tuner the noise on the
receive antennas would disappear.....well it turns out that in 1945 when tech
material corp built this unit using braid as interconnecting leads was cool not
so my tuner was a rebroadcaster....all the junk braid replaced w 1/4 inch
tubing and quiet bands again...this is a wake up call look at your station your
neighbors wifi stuff my be heard because of a rectifying joint in your
station...simple things like coax connectors with the shield not soldered correctly
will cause a hell of a lot of problems dx on ray nr1r
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