[TowerTalk] XM240 interaction - question

k6ll@juno.com k6ll@juno.com
Sat, 17 Oct 1998 23:16:27 +0100



On Sat, 17 Oct 1998 22:48:20 -0700 Sam Ferris <ve5sf@sk.sympatico.ca>
writes:

>  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.

I have a 40-2cd mounted six feet above a KT-34XA, booms
parallel. The 40 is set for a compromise between cw and
mid-band settings.

Here is the swr curve on 40:

7.0 - 2.4
7.1 - 1.4
7.2 - 2.2
7.3 - 2.8


Dave Hachadorian, K6LL
Yuma, AZ
K6LL@juno.com




















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