[CQ-Contest] SO2R interference help update

[Mike Smith VE9AA]

Hi Dan, 

 

I am late to the party. I am not your best resource, but will tell you that
I contest here on ~2.2acres

LP (and even some HP) nearly interference free with no filters and no stubs
! (gasp!)

 

My secret? Well..I do have 2+ acres to spread out on and have my antennas
separated as far as possible in a NW to SE line...NW is my least used
direction..at least until all the Japanese hams and F2 prop comes back.

 

My other secret?  On radio #2 is only 1 horizontal antenna.( a modified
ZS6BKW )

 

On radio #1 is a variety of verticals or vertical arrays.

 

I did oscilloscope measurements for all antenna combinations and was w/in
the safe zone (even at HP), but there are some combos that create a little
hash on the 2nd band that's not conducive to doing true 2BSIQ.

 

F'rinstance, if I am beaming WNW (W7/JA) on 20m with my vertical 4-square  I
am aimed right at my ZS6BKW if that was on 40m.  Ditto if I was transmitting
on 40m, beaming NW..so I can really only can do Run + S/P on those band
combos when aimed NW..and sometimes even when aimed SW..the lobes are pretty
wide on my 4-squares. Most other bands I can do RUN/RUN or a very quiet
RUN+S/P if I choose.

 

So maybe that helps.I am not sure what you have for antennas, or maybe you
only have 1 antenna for each band.

 

I know my SO2R setup is not setting any fires in the Pacific (or even EU for
that matter) but I don't need band decoders, a full array of filters or even
switchable coax stubs..I tried some stubs and in 1 case it made it worse.  I
will wait for Jim to tell me that I did it all wrong, hi !

 

I did get the FB book by George, W2VJN which helped with measurements.

 

I also swapped some power supplies around in the shack one time which then
lessened my interference and one time, for a quick test, physically swapped
radio #1 for radio #2 and it also lessened interference.  I have no idea why
that worked.I just thought I'd try it.  They are identical IC-7410's.

 

Lastly, you have to stay away from your harmonic.  Ie: if you are on 7.010
you're going to destroy the area around 14.020, so park higher up in the
band.like 7.040 - because there are many less stns on 14.080 for example

 

HTH

 

Mike VE9AA

 

 

TNX to all who responded. I have a sense of direction and will begin
diagnosing.

 

So far I have transmitted on 40 into a dummy load connected with a short
cable 

with Radio 1 (K3) and listened on 20 with the 1000MP on the tribander.
Turning 

the rotator seems to indicate the harmonic is coming from the shack. Now I
will 

be checking all cable and connectors, unplugging all wall warts and
eliminating 

any antenna switches in the path of the tribander. Probing with my Tecsun SW
on 

the harmonic has not revealed any true peaks on any piece of gear so far but


I'm just starting.

 

If I have a revelation and/or some success I'll repost with my results.

 

As an aside I'm making a flow chart to show all antennas and switching for 

future reference. Amazing how much "stuff" gets added over the years!

 

73 Dan W8CAR

[CQ-Contest] SO2R interference help update

Mike, Coreen & Corey

Keswick Ridge, NB