Where does one need to place chokes with multiple RF handling boxes in the
chain? My layout is?
160 M Twin Lead (300 ohm ladder line) and 80 M Twin Lead (etc.).
40 M ? 12 M 43 ft Vertical
20 ? 10 M tribander.
(Total of 4 antennas)
Each antenna connects to a ¼ inch thick copper bulk head plate outside the
window of my shack. The bulk head is bonded to my house ground (and
utilities). My system ground inside is bonded to the above mentioned
bulkhead.
Each antenna feeds a multiple position Alpha Delta Switch. Then the chain
flows as: antenna selected > auto tuner > low pass filter > transceiver. The
cables between the bulk head and the switch are approximately 10 feet in
length. Inter connecting cables between the switch, tuner, amp and low pass
filter are no more than 3 feet long (if that much). The cable between the
transceiver and the amp is RG-214 and about 12 feet long. I am not able to
get the transceiver any closer to the other equipment due to the physical
layout of the room and my operating desk.
Currently I have each jumper between boxes broken with inline RF chokes. I
now realize they are the wrong material and not sufficient for suppression.
I am having significant interference on 10 M. The same is present on 15 and
20 M to a much lesser extent. The same interference is not present (the best
I can tell) on 160 and 80 M (Twin Lead Marconi?s) although there are other
noises sources who origins have not been determined as yet.
Initially I was going to construct two of Jim?s chokes (type 31 Fair-rite
toroids) and place them (in series) at the transceiver. The second choke
will have fewer turns of RG-213 to get the 10 M coverage I need. Where else
do I need to place a choke (s). I am trying to put together an order for
Fair-rite suppression materials, toroids, clamp-ons, and etc. I have a very
good idea of what I need to suppress noise relating to the interconnects
between computers, monitors, cable modem, router, network switch and etc.
The source(s) of the interference is another topic in itself but I am on top
of that.
Thanks
Glenn Pearson, WU2G
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