Roy,
There are 2 possibilities that occur to me. First, yes, RF in the shack
is a good possibility with an OCF antenna. If you can add a 1:1 current
balun (actually a line isolator) at the shack entry AND ground the coax
shield at the point where the isolator is placed, that will go a long
way toward minimizing RF in the shack. If you have a W2DU type balun,
use that, otherwise a coil of coax (about 7 turns 4 to 6 inches in
diameter) will serve the purpose. Run a short ground from the coax
shield on the antenna side of the balun. If you can create a zero
length path to ground that is best.
The second possibility is that your KPA100 is suffering from the 40
meter parasitic - that parasitic was the incentive for the KPA100UPKT,
and if you do not have this latest change installed, I strongly
recommend it.
73,
Don W3FPR
Roy Morris wrote:
A little background info-- my KAT100-1 is grounded, it is connected to a
Carolina Windom 80. It will tune all bands from 80 through 10 meters and give
a 1:1 SWR on all bands except for the phone band on 40 meters. If I go from
the CW portion (7040 Khz for example) straight to the the phone segment, the
K2/100 will click, the KAT ANTENNA LED and POWER RANGE LED will flash brightly
momentarily and the KAT becomes unresponsive. The SWR is high when this
happens, and VFO #2 reverts to VFO#1. If, however, I sneak up the frequency in
approx 20 Khz increments and tune the KAT at each increment, I can tune the KAT
all the way to 7300Khz with a 1:1 SWR.
I have run all the L and C menu parameters, and all the relays click as they
should. The parameters were checked starting on 10 meters and working down the
bands. There were no components that showed a too large or small change in
relation to the others tested. These were my readings on 40 meters:
I am beginning to think that stray RF is created by the off-center fed antenna, and the KAT MCU becomes RF saturated and cannot tolerate it on the higher portion of 40 meters. If I tune the KAT into a 50 ohm dummy load, it seeks and attains a 1:1 SWR on all bands (including 40 meters). Any comments appreciated. Roy Morris W4WFB
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