From: cqbi...@msn.com
To: sdell...@facstaff.wisc.edu
Subject: RE: [Elecraft] K3 RFI Susceptibility
Date: Wed, 22 Dec 2010 10:13:49 -0600
I have had similar issues with my K3/10, but I was asking for trouble. I
have an involved external sequence switcher and band decoder for all the
VHF/UHF/Microwave transverters. Involved is an unshielded wire that runs
between my sequencer switcher and the PTT circuit, accessed at a mike cable
extension on the K3. The TX function for the K3 is operated by the sequencer.
On 6m when running the 250w, the amp RF gets into the keying circuit. With a
bit of lead dressing I have been able to avoid the problem, but I need to do
something a bit more "evolved" for the problem.
73 Bill K0AWU (EN37ed Minnesota)
------------------
> Date: Wed, 22 Dec 2010 09:33:51 -0600
> From: sdell...@facstaff.wisc.edu
> To: elecraft@mailman.qth.net
> Subject: [Elecraft] K3 RFI Susceptibility
>
> While using my shunt-fed tower and amplifier on 80 and 160 CW, the K3 keying
> became erratic. The problem went away when I unplugged the spare headset
> from the rear panel jacks. The front panel jacks aren't a problem, no doubt
> because their shields go right to the chassis. If you use the rear panel
> ones at high power, it would be wise to wrap the cord around a ferrite core.
> I didn't have any trouble with the other rear panel cables, but I put cores
> on them anyway.
>
> My shack is a high-RF environment on those bands, as it's only about 10
> meters from the tower, but it's probably not the worst the K3 is likely to
> see. (Field Day, expeditions?) I've had to take measures to keep RF out of
> other equipment, though not the 60 pound behemoth next to the K3.
>
> I haven't looked into it, but maybe there's an easy way to ground those rear
> panel jacks more directly to the chassis. (This is a classic cause of RF
> susceptibility.) If not, a few ferrite cores is a small investment.
> 73,
>
> Scott
> Scott Ellington
> Madison, Wisconsin
> USA
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