[TowerTalk] Re: [Antennas] Dipole

[n7ws@azstarnet.com]

At 06:37 PM 10/22/00 EDT, ATanner283@aol.com wrote:
>Hi all.....I am putting together a rotatable diplole for 40  meters. I am gg 
>to mount it about 10 feet or so above a HyGain TH-7. What are the thoughts
on 
>this??? Should I mount it at 90 deg to the tribander or 0 degrees?? I just 
>cant get it much above that. Have Rohn 25 tilt over tower at 60 feet. Thanks 
>for any help..............Al/W8FAX
>


Al,

A couple of thoughts:

1) Have you tried modeling this?  You can do a reasonable job with the
Eznec demo available at www.eznec.com.

2) You say "tilt over tower" do you mean fold-over?  If so, have you
considered the extra moment that the tower will be subjected to during
raising and lowering.  The moment will be the weight of the element times
the length of the additional mast length (10 ft?) plus the weight of the
mast times half of its length.  If in fact you have a Rohn model FK-25 58'
tower, a (very) old data sheet I have before me shows the "Safe Load at
Apex, Lbs. as 100.  I don't know what the combined weight of your TH-7 and
rotator are, but I'd guess you're close to the limit already.

Regards,

Wes  N7WS


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