[NLRS] 70-cm Antenna Dilemma

[Brad Johannes]

Sounds like the exact antenna I have up from N0VZJ. Maybe he remembers the 
brand? I'd have to look at my log from the contest in Jan for grids worked, 
but I know I made contacts with it and 25w no problem and the SWR was fine. 
I'm feeding it with about 70' of...cough cough.. radio shack RG8.
Brad
KB0HNN


>From: "Carl Estey" <cestey at mn.rr.com>
>To: <nlrs at mailman.qth.net>
>Subject: [NLRS] 70-cm Antenna Dilemma
>Date: Wed, 7 Jun 2006 07:03:19 -0500
>
>
>
>In the Spring of 2005 I obtained a used 16-element 432-Mhz yagii of 
>un-known
>design.  When I got it up on a 40’ tower and fed it with 65’ of LMR-400 I
>found performance over a 50-mile path very poor.  Last week I put up a 48’
>piece of Andrew 7/8” Heliax and a 15’ LMR-400 Ultraflex jumper at the
>antenna the best I can do on a fifty mile path with 100-watts at both ends
>is 20-24 db above the noise – somewhere there is a loss of 40-50 db!!
>Physical exam of the antenna shows nothing wrong, which makes me think the
>balun is the problem – and it is a ½ diameter six-inch long tube that is
>sealed (soldered) on the end with the female N-connector.  One the opposite
>end of the balun from the N-connector are flat zig-zagged metal straps that
>go to several of the elements.  Does anyone recognize the design of this
>16-element antenna and have any specs on it?
>
>
>
>Yesterday someone loaned me a 25-element 17’ 5” long K1FO-style yagii.  I
>tried the same path with similar poor results.  Adjustment of the T-match
>failed to provide proper SWR at 432.1 and the lowest point was at 430 Mhz
>despite a large amount of re-adjustment.  The measurements (made mostly in
>the dusk so forgive small errors) are as follows: