Herb: What do you mean "sweet point?" This has always been a mystery to
me. I have a 90' tower with a TH-& etc on top that I am getting ready to
feed. I have heard "feed it at the top (just under the beam)" and I have
heard 55' up. How does one go about finding the right spot to attach gamma
rod to the tower? I plan on using 1/2" hardline outer conductor for the
line.
Thanks to all for the good advice on this reflector and 73, Wayne N1WR
--------------------------------------------------
From: "Herb Schoenbohm" <herbs@surfvi.com>
Sent: Saturday, April 24, 2010 6:20 AM
To: "w8uvz" <w8uvz@voyager.net>
Cc: "Phil LaMarche" <plamarc1@verizon.net>; "Topband"
<topband@contesting.com>; "Kyle N4NSS" <n4nss@yahoo.com>
Subject: Re: Topband: Shunt fed tower
> w8uvz wrote:
>> Hi Phil
>>
>> There is an excellent article in Ham Radio May 1975 by John True, W4OQ on
>> "shunt-feed systems for grounded vertical radiators". His system uses an
>> omega match for matching the gamma rod (or wires) to the radiator.
>>
>> Using large diameter tubing or multiple wires for the gamma will result
>> in
>> more usable bandwidth on top band.
>>
>>
>>
>
> Using the other solid aluminum shield on discarded 3/4 inch CATV cable
> end runs (called by some 750 or .750) spaced 24 to 36 inches from a
> towers is a significant improvement over a single #8 wire. Yet a
> skeleton cage around the tower and taped at or near the "sweet point" of
> 3 or 4 wires is even better.
>
>
> Herb Schoenbohm, KV4FZ
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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