---Sam Ferris wrote:
>
>
> Wonder if any CC 402cd or XM240 owners can give me some advice
regarding
> interaction associated with a XM240 and a TH7 stacked about 6 feet
apart
> (that's all the space I reasonably have). Here's the situation.
>
> Put up my new XM240 a couple of days ago - 5.25 hours on the tower
> removing the old Hygain 402 BA and pulling and assembling the XM240
up
> through a couple of other antennas. The TH7 is mounted at 70 feet
just
> above the top of the tower and the XM240 is about 6 feet above that.
The
> booms are perpendicular to each other since that is the way that I
had
> the hygain 402 mounted previously to reduce SWR impacts on 15 metres
on
> the TH7. Presently the SWR on the XM240 is a little high, bottoming
> out at about 1.55 at 7.050 , 1.8 at 7.000 and 2.0 at 7.125. I set
it for
> the CW setting in the manual and followed the advice regarding the
> measurement mistakes in the manual posted by others - most helpful.
In
> comparison to the Hygain 402, it seems that impacts on the TH7 are
about
> the same, the 15 metre SWR curve looks about the same as before and
the
> SWR on 10 and 20 metres is now actually lower than with the previous
40
> metre antenna.
>
> My question is if any others have similar setups with PARALLEL
BOOMS, and
> if such a change to my system would reduce the impact on the XM240 by
> lowering the SWR. Bottom line is I am not all that anxious to make
many
> more trips up the tower to spin it.
>
Sam,
I have had a similiar setup for quite a few years. I have a TH6DXX @
62ft and a 40-2CD @ 72 ft. The TH6 is setup with the CW dimensions
and was up some years before I added the 40-2CD. Both boom are
"in-line". After installation of the 40, I noticed that the VSWR of
the TH6 on 15M went up, from like 1.2:1 to 1.5:1 at 21025. It seems
like the F/B on 15 degraded slightly also. The pattern is still good
and the gain seems up there as it will bust pileups in a DX contest
with all the big guns. the 40m VSWR (antenna set for CW) is almost
exactly per the CC specs. I think the 40 will affect the 15, not the
other way around. Yours spacing is a little tighter than mine so the
effects may be more pronounced. Also, a TH6 may be more/less effected
than a TH7. GL with ur project.
73, Stew, K3ND
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