[Antennas] Re: Gamma Match

[Sergio Finotto]

Hello Alan


I check my  yagi antennas mounted vertical in a metallic
pole no mare high than  3 meter.
Is easy and accustomedly  dont vary when the antenna
is mounted definitive on air.
Sergio IV3MUC
----- Original Message ----- 
From: <antennas-request at mailman.qth.net>
To: <antennas at mailman.qth.net>
Sent: Wednesday, May 16, 2007 10:01 AM
Subject: Antennas Digest, Vol 40, Issue 4


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>    1. Gamma Match (Alan)
>    2. Re: Gamma Match (Val)
>    3. re:Gamma Match (Alan)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 16 May 2007 17:24:49 +1200
> From: Alan <zl3kr at ihug.co.nz>
> Subject: [Antennas] Gamma Match
> To: antennas <antennas at mailman.qth.net>
> Message-ID: <464A95A1.9030505 at ihug.co.nz>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Can anyone suggest what I may have set up wrong.
> I have a homebrew 4 el Yagi for 10 metres which appears to be working
> well, however I do not seem to be able to get the swr down below about 2
> or 3 to 1.
> The set up is, the driven element is one inch Diameter, the gamma rod is
> half inch diameter
> and the spacing is approx 3 inches. I have a 100 pf variable capacitor
> which is fully meshed
> and turning for less capacity makes the SWR worse. From books that I
> have read, 100pf
> sounds to be very much on the high side. I have adjusted the shorting
> bar but do not seem to be able to improve the SWR.
> I Might add that my situation is such that when the antenna is swung
> over it is very close to a metal sided garage and therefore I have to
> swing it back up to check out what if anything has happened
> which in itself is kinda frustrating but you put up with  what you can
> have hi.
> Would changing the diameter of the gamma rod maybe help by changing the
> range of
> impedance(I think I have that right).
> Almost to the stage of considering changing to a Beta Match to see if I
> can get the SWR
> better, I am sure as good as it is working now ity would be even better
> with a decent match.
> Any helpfull ideas would be appreciated.
>
> Alan ZL3KR
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 16 May 2007 09:21:58 +0300
> From: "Val" <val at vip.bg>
> Subject: Re: [Antennas] Gamma Match
> To: "antennas" <antennas at mailman.qth.net>
> Message-ID: <009f01c79782$843d6ff0$0201a8c0 at TATI>
> Content-Type: text/plain; charset="iso-8859-1"
>
> > Would changing the diameter of the gamma rod maybe help by changing the
> > range of  impedance(I think I have that right).
>
> I don't think so. The length is what matters. How long is the rod?
>
> 73, Val
> LZ1VB
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 16 May 2007 19:11:33 +1200
> From: Alan <zl3kr at ihug.co.nz>
> Subject: [Antennas] re:Gamma Match
> To: antennas <antennas at mailman.qth.net>
> Message-ID: <464AAEA5.5050104 at ihug.co.nz>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> I do not know what the actual length of the gamma rod is with out
> dropping the antenna
> to measure it but a rough guess would be  around 3 feet and the shorting
> bar around the 2 foot mark,
> I have moved it quite a bit without seeming to be able to reduce the SWR.
> I am sorry I do not have the equipment to measure the R and J
>
> Alan ZL3KR
>
>
>
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> End of Antennas Digest, Vol 40, Issue 4
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