I made a misstatement; the stator of the shunt capacitor connects to the
rotor of the gamma capacitor. The rotor of the shunt capacitor connects
to the radial system and the coax shield..sorry about that, folks.
Yes, there is a very high voltage at the feed point in some cases.
A vacuum variable or large cap is required in some cases. My
Omega match is two motor driven vacuum variables.
> I have this system since 2 years with good results, on my self-supporting
> tower 75 feet high, with KLM 20M-5 and Hygain 105CA on top.
> Only two questions:
> Why the stator connected to the coax shield and not to the center conductor?
> I'm using a 8877 in my power amplifier, and there is nothing to be done,
> with more power than 1000 watts, for skip the arcing in my shunt air
> condenser with the arcing (plate separation about 1/4 inch).
> 73 from Barcelona.
> Alberto Perello
> -----Mensaje original-----
> De: email@example.com [mailto:firstname.lastname@example.org]En
> nombre de Phil Clements
> Enviado el: martes 7 de diciembre de 1999 23:03
> Para: Bob See; email@example.com
> Asunto: Re: [TowerTalk] Feeding tower on 80
> Hi Bob,
> ON4UN's new book from ARRL, "Low Band DXing" covers this
> topic very thoroughly, plus many other low band antennas. I highly
> recommend it.
> You do not want the gamma rod (wire) to move around. Aluminum
> tubing is great, but large copper wire is OK if it is made immobile.
> with insulators.
> Use an Omega match; it will allow you to QSY all over the band,
> plus it will not matter where you put the gamma wire on the tower.
> I suggest about 30 feet up. The stator of the shunt capacitor in the
> Omega match and the shield of your coax feedline must be bonded
> to your radial system.
> If you get it resonated to your desired frequency and you are not at
> 50 ohms, let me know, and I'll give you further info.
> That system will be a real killer antenna on 80m.
> Phil, K5PC
> > I would like to feed my windmill type tower on 80 meters with a gamma
> > match. The tower has a triband beam at about 57 ft. It has four legs,
> > about 5.5 ft apart, (free standing). A .JPG picture available if
> > interested. It is grounded by many radials.
> > I would like to shunt feed the tower on the low end of 80 meters using a
> > gamma match feed. I am 75 yrs old and do not look forward to
> > multi-climbings up the tower to find the best point to tie the gamma
> > rod. Also, can I use copper wire for the gamma match or would aluminum
> > tubing be better?
> > Can anyone tell me a past QST article or discussions on Towertalk that
> > would educate me on the parameters of the gamma match that I might
> > expect?
> > Thanks, Bob See, N5PC@Poncacity.net
> > --
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