[TowerTalk] Detuning booms?

[Michael Dinkelman]

Hi Steve

I have 2 yagi's, a C31XR and a 3el 40M (old KLM) I just
refurbished and put up underneath it. As long as the two
booms are lined up. All is fine. (At least that makes it simple :>)
If they start pointing in different directions, the
20M SWR starts rising.

The 40M antenna's boom is about 30+'. I figure it's close
enough to 1/2 wave on 20M to make a difference. I might be
able to raise the C31XR a couple more feet on the mast - there
is about 8' between them now. I expect we'll try that first but
I don't expect it to make a difference.  The 40M is on a
Tic Ring and isn't going anywhere for now (it took 3 months
to align the moon and the stars enough to get it on the tower :>).
So that'll make  it hard to hang wires off the end.  :>)

At least I have a work around for now - keep 'em lined up while
I'm on 20M. :>)




K7LXC at aol.com wrote:
> In a message dated 10/17/2008 10:18:08 P.M. Pacific Daylight Time, 
> towertalk-request at contesting.com writes:
> 
>      >  I swear I've seen stuff on detuning a boom. I even thought I saw
>     it in the
>     ARRL Antenna handbook. However, I can't seem to anything.
>      
>         What are the circumstances that made you determine that you need
>     to detune a boom? You have 2 yagis and have some destructive
>     interaction between them? What are the antennas and what are you seeing?
>      
>         If the boom is interacting, doesn't that mean that it resonates
>     somewhere where you don't want it? How about hanging a piece of wire
>     off of each end of the boom? That would change the resonance.
>      
>     Cheers,
>     Steve    K7LXC
>     TOWER TECH 
> 
>  
> 
> 
> 
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