I am not sure how low the antenna is, but moving from 30' high to 70'
should not make any significant SWR change.
John KK9A
To: towertalk@contesting.com
Subject: Re: [TowerTalk] 402CD
From: Roger Cooke G3LDI <roger@g3ldi.co.uk>
Reply-to: roger@g3ldi.co.uk
Date: Tue, 02 Dec 2014 20:20:00 +0000
Hi.
Many thanks to all who replied. I have kept all the emails and it looks
like there are a couple of
possibilities.
1 The loading coils are not making proper connection, some corrosion may
have crept under the insulating sleeving covering them. This seems a
common fault so I will be having a look at those.
2 A couple of you suggested that it could be too low. I have it installed
on a 70ft crank-up tower which I have to finish roping as yet in order to
crank it up. I'm not sure if this would have accounted for the 3:1 SWR,
which seems very high to me. My linear would baulk at that!!
I did clean the beam thoroughly before putting it up and I used aluminium
graphite anti-seize compound on the elements when assembling it. I used a
1:1 toroidal balun at the feed point and
I used Westflex 50 ohm low-loss coax.
Thanks again to all who replied and I will follow up on all the
suggestions. Hopefully they will work out! I shall crank the tower up to
70ft before testing again. Even that is low for 40m I do realise! I am
just too much of a coward to stack it above my 4-el steppir which is on my
120ft
tower. I guess it might be an idea to swap them around!!!!
73 de Roger, G3LDI
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