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[RFI] Problem solved

To: rfi@contesting.com
Subject: [RFI] Problem solved
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sun, 28 Nov 2010 21:29:21 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
A while back I mentioned when operating 75 the system worked fine until 
I passed roughly 1KW out.  At that point all the LEDs on the 6-0pack 
(SO2R) controller would light to full brilliance.  I tried many turn 
chokes on several ferrite cores (#31 mix), but nothing appeared to get 
rid of the RF in the shack. So I had pretty much avoided operating on 75 
this fall, but 40s been open world wide any way.

This afternoon I was making up some current baluns using 5 2.4" cores 
(#31 mix) and 5 turns of LMR-400 and LMR-400UF. The coils are fairly 
tight at roughly 5" per turn.  I put 4 dabs of super glue equally spaced 
on the faces of the cores and press them together which forms a 
cylinder.  Although not terribly sound mechanically they hold well 
enough to complete the winding process and that's good enough.

While contemplating making up center connectors for some 75 meter fan 
dipoles, It occurred to me that it might be worth a try adding one of 
those baluns just prior to the remote antenna switch, just before the 
coax reaches the tower from the 75 meter sloper to the SW.

Tonight I was checking out the antenna when I realized I hadn't checked 
for RF getting into the LEDs and control lines to the 6-pack when 
operating on 75.  I had the tuner set for 1:1 SWR at that frequency, 
flipped the amp switch to operate, and hit the key.  1500 out and not a 
sign of RF feed back.

73

Roger (K8RI)
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