[Towertalk] More on tree antenna mounts

[Peter Sundberg]

Making the cross pipe long will indeed reduce rotor instability but also
degrade the beam quite a lot. The same will happen if the cable is made of
conducting material, especially when the elements are parallell to the
cable or the cross pipe.

I've seen better ideas...

73/Peter SM2CEW
www.qsl.net/sm2cew


At 15:29 2002-09-07 , you wrote:
>
>
>>
>> > > Another way is to string a guy wire between two trees; use it to hang a
>> >  > rotor upside down and a beam hangs from the rotor.
>> >
>>     A good way to fill up a HAM IV or T2X with water. Don't know about
>
>Don't think you actually have to hang the ROTATOR itself upside
>down. Just mount the normal top side to the fixed guy by using a
>short vetircal pipe mast welded to the center of a long horizontal pipe
>which is supported by the horizontal cable.  Then mount the beam to the
>normal bottom side of the rotator.  Easy to do if the bottom side has
>a mast mount clamp, but it could also be done with a flat plate bolted
>to a flat-bottomed rotator and then the plate could be drilled for U-bolts
>to attach the boom.
>
>Probably not all that wonderful around here were the trees are only
>25 ft tall, but it is an interesting idea conceptually--at least
>for relatively modest beams.
>
>I could also see this technique used between two towers when tuning
>a beam and rotation is also desired.  But not sure how long the
>swinging would continue after movement (making the cross-pipe long
>would greatly reduce the rotation instability, but not the bouncing
>and swaying mode.
>
>Probably most useful as a Saturday-morning mental exercise than
>as a real project--but it is always nice to have "secret weapons"
>for unusual circumstances--such as Field Day in the Pacific NW.
>
>John   W0UN
>
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