I had a friend spend hours trying to match an antenna with a short piece if
coax. Turns out his proximity to the antenna caused the SWR to be high. When
he installed a 1/2 wave length if coax and took his measurements at a distance
he was successful in adjusting the match.
Sometimes it doesn't pay to be too close to your antenna ;-)
73
Dave
Wa3gin
Sent from Dave's iPhone4 ;-)
> On Jul 3, 2014, at 10:32 AM, TexasRF--- via TowerTalk
> <towertalk@contesting.com> wrote:
>
> The half wave multiple is certainly needed for taking R +j measurements.
> For simple vswr measurements the vswr is not changed by the line length as
> long as line losses are low.
>
> This is assuming 50 ohm test equipment and a 50 ohm line of course.
>
> 73,
> Gerald K5GW
>
>
>
>
>
> In a message dated 7/3/2014 6:52:28 A.M. Pacific Daylight Time,
> w4byg@att.net writes:
>
> Additionally, I would connect the analyzer with a half wave length of coax
> instead of the 4 foot piece. The half wave length will reflect what the
> actual impedance at the antenna feed is. The 4 foot piece will only do
> that
> if/when the antenna impedance is actually at 50 ohms. Remember to
> calculate
> the half wave length by the velocity factor of the cable you are using.
>
>
> Ray, W4BYG
>
> Kindness is the inability to remain at ease in the presence of another
> person who is ill at ease, the inability to remain comfortable in the
> presence of another who is uncomfortable, the inability to have peace of
> mind when one's neighbor is troubled... Samuel Holdenson
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of John
> Lemay
> Sent: Wednesday, July 02, 2014 11:14 AM
> To: 'James Archer'; towertalk@contesting.com
> Subject: Re: [TowerTalk] Advice Wanted-Tuning A 10 Meter Telrex Beam
>
> Hopefully, you are taking measurements with the aerial clear of the ground,
> and pointing skywards ? Otherwise ground proximity will make an impact.
>
> John G4ZTR
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> James
> Archer
> Sent: 02 July 2014 14:58
> To: towertalk@contesting.com
> Subject: [TowerTalk] Advice Wanted-Tuning A 10 Meter Telrex Beam
>
> Tuning a Telrex 10M523 (Telrex 5 element beam on 23 foot boom)
>
> After several days of work on the ground working with the matching system
> and trying multiple combinations of driven element length to the Telrex
> match position-the best we can get is an SWR of 2.3 at 28.500. We are using
> an MFJ tuner through a 4 foot piece of coax to the antenna. Antenna has a
> tuned matching stub set for 28.500.
>
> We have followed exactly the specifications from the 5 page Telrex
> instructions that are beautifully illustrated.
>
> This is a wonderfully built antenna and we are very keen to get this tuned
> up right and in the air working!
>
> Anyone have any golden words of advice, we are of course looking to get the
> SWR down below 1.5:1 at 28.500
>
> Thanks in advance for any help you can provide. Replies to N3ZS at
> james.archer at erm.com
>
>
>
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