[Rover] Interstation Interference in Multi-Op Rovers

[Robin Midgett]

I don't know how "everyone" handles this, but having had the same problem
20 years ago, I feel your pain. We (NT4L) never did address the issue due
to life circumstances ending our roving adventures.
What you're getting is most likely a harmonic from the 6m transmitter that
lands in the pass band of the 2m Rx.
For reference:
http://forums.qrz.com/index.php?threads/vhf-notch-filter-with-coax.408931/

http://www.repeater-builder.com/antenna/heliax-6m-filter.html
(note the comment about the 'tuning rod stopped turning slightly below 51
MHz'); you might try to find one of those
Telewave 45 MHz cans, but it'll be BIG, probably much bigger than you want
to haul around in your rover vehicle.

It seems that one of the tuned stubs from large coax would be worthwhile.
Configure one as a narrow band pass on the 6m Tx, and perhaps another as a
notch filter on the 2m Rx.

https://is.gd/yHBWkd




On Thu, Sep 21, 2017 at 3:17 PM, Sean Waite <waisean at gmail.com> wrote:

> How does everyone handle this?
>
> Our setup is as follows:
> Front seat station, 2m and 70cm
> Rear seat station, 6m and 1.25m
>
> The front station uses a drive-on mast with the 2 and 70cm antennas on it,
> the rear station uses a hitch mount mast with the 6 and 1.25 antennas on
> it.
>
> The 6m station has a bandpass filter and the 1.25 station is on a triplexer
> that kinda sorta almost (not really) filters out some of the crud. We're
> planning a bandpass filter on the 2m station, but it hasn't happened yet,
> and I'll be building up some coax stubs (likely 6m and maybe a 70cm
> bandstop to put on the 2m station).
>
> Depending on which direction the antennas are aimed, we get somewhere
> between a faint amount of QRM up to rendering it useless on 2m when 6m
> transmits. I think some of the filtering will help, but when you are
> transmitting 100W of 6m into a moxon and it's aimed right up the rear end
> of the 2m yagi I'm unsure how much that will do. We got around it somewhat
> in the September rove by calling CQ at the same time.
>
> Any other recommendations here? One idea would be to bond the grounds on
> all of the radios together, but I'm leaning towards that being worthless.
> We also could put 6 and 2 at the same station, but we're hectic enough at
> times that whichever op was on that station would be pretty busy. It might
> also be a bit boring on the 222/432 station, but maybe we'd grab a few more
> random contacts on there by calling CQ. The preference would be to keep the
> band split unless it's truly hurting us.
>
> Thanks!
>
> 73 de Sean WA1TE (K1SIG/R)
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