TT:
To quote Tom N4KG: <Time for a repeat of this 'oldie but goodie' from
the archives by Ed Gilbert, WA2SRQ. See below.>
http://lists.contesting.com/archives//html/Towertalk/2001-03/msg00125.html .
What I got out of the posting is that a random-wound choke is not as
effective at high HF as is a solenoid (i.e., carefully) wound coil of coax.
I used a small paint can as a removeable form when I wound the balun for my
Bencher Skyhawk. Consists of five turns about 5 inches in diameter, held in
position with tie wraps and tape. I measured (with my MFJ analyzer) greater
than 250 Ohms impedance of the shield from 14 MHz through about 29 MHz.
73 de
Gene Smar AD3F
----- Original Message -----
From: "Al Baker" <w5iz@yahoo.com>
To: <towertalk@contesting.com>
Sent: Wednesday, July 14, 2004 6:17 PM
Subject: [TowerTalk] Mosley and chokes
> Old Carl suggested a choke be inserted in the coax "to eliminate stray RF
> on the coax line". For example, with the PRO 96 he suggested 10 turns,
> 10" diameter done simply by coiling the coax overlapping in one's hand.
> Tape the coil in 3 places and mount it directly beneath the boom and feed
> point on the phasing lines.
>
> With the passage of time and improved analysis, I guess his "rf choke" was
> not the most efficient...and a good balun replaced it.
>
> Seems that keeping rf off the coax was one of the keys to performance of
> these old multi-band antennas.
>
> 73 de
>
> Al, W5IZ
>
>
>
>
>
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