Hi Geo,
I don't know what frequency you are using to make your measurements, but
the numbers sound about right for 21 or 28 MHz (~1dB/100 feet). The 14dB
return loss of the balun/antenna feed corresponds to a VSWR of 1:5:1 which
seems reasonable for a properly adjusted antenna. Is this consistent with the
manufacturers specification? Also, how does the return loss vary with frequency
(e.g. is the maximum return loss correspond to the desired center frequency of
the antenna? Also, can you disconnect the balun from the the driven element
of the antenna? If so, you can replace the antenna with a non-inductive 50
ohms resistor (200 ohms for a 4:1 balun), and check the return loss of the balun
by itself.
What kind of antenna are you using?
Mike, W4EF..............
----- Original Message -----
From: <K6TFZ@aol.com>
To: <towertalk@contesting.com>
Sent: Sunday, August 12, 2001 1:50 PM
Subject: [TowerTalk] Return Loss of feedline
>
> I am using RG-214. About 125 feet from shack to tower base with return loss
> of about 2.3 db when not connected. About 85 feet from tower base to relay
> box with return loss of about 2 db when not connected. From the relay box to
> a Cal-Av balun feeding the driven element, it is about 14 db but I can't
> disconnect the feedline to the balun. Is there an easy way to know if that
> length is O.K or if the balun is working correctly? I also tried to lower the
> resonant freq of the driven element by lengthening the feed wires from the
> balun to d.e. but it didn't seem to work. Any ideas? TIA, Geoff, K6TFZ
>
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> -----
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>
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
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Administrative requests: towertalk-REQUEST@contesting.com
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