[RFI] 2nd harmonic help

Ken Eigsti diverken at chaffee.net
Wed Feb 4 09:36:59 EST 2009

RE: Follow up on 2nd harmonic.

Thanks to all the guys who replied.

The antennas are in place so they cannot be moved. The 40 is a C39 XRN
(Force 12 40-10 yagi) at 90 feet. It is approximately 100 feet from the
STEPPIR (3 element at 50 feet) that is connected to the 2nd radio. All fed
with LMR 400.

The consensus seems to be that the 2nd H. will not be eliminated but that
"heavy" filtering might make it usable. That is the approach I am going to
take with a filter plus chokes on the coax  and other lines.

Now, while transmitting on 40 and the 2nd radio's antenna disconnected,
there is still a spike on the band scope. This obviously means that the
separation of the antennas is not all the problem as the problem exists with
no ant. connected. I will work on some of the in shack filtering and see if
it can be minimized.

Thanks again for the suggestions.

CU in the RTTY WPX

On Tue, Feb 3, 2009 at 6:39 PM, Ken Eigsti <diverken at chaffee.net> wrote:

> Hi
> My first post to this reflector and if it is redundant, please forgive.
> Problem: I am running Two ICOM 756PRO3's in a SO2R configuration. I have
> ICE filters in line with both rigs. When operating on 40 the 2nd harmonic is
> wiping out 20 meters on the second radio. I have had others suggest to use
> some ferrite chokes. I might add I am mainly in the RTTY contests and the
> 2nd harmonic of 7040 is 14080,right in the rtty band on 20.
> Just wondering which type? Use the "rods" and tape the coax parallel to the
> coax? Or the clamp on type that clamp around the coax? Or???.and best place
> to get them? Any suggestions will be helpful..
> 73 and thanks
> Ken W0LSD

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