[UK-CONTEST] Vertical Dipole

[Stewart GM4AFF]

Jim,
I'm using vertical dipole(s) here in 5X and they have been brilliant for me.
I have a balun at the feed point. I threw a string up a tree and hoisted one
end up. The feed point comes away at 45 deg to the ground/antenna, and the
bottom leg on 20 and 30m has to be more horizontal than vertical. Perfect
SWR every time. As to whether I'd be better with a ground plane is open to
test/discussion, but these are so simple.
I'm out in the bundu at the moment but should be back in Kampala tomorrow PM
and QRV on 30m in the evening. Amazing having high speed wifi in the middle
of the rift valley!

73
Stewart
5X1SF / GM4AFF

-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com]On Behalf Of Stewart Rolfe
Sent: 26 July 2011 15:35
To: uk-contest at contesting.com; mm0bqi
Subject: Re: [UK-CONTEST] Vertical Dipole


Jim,

Are you using a choke balun at the feed point? That'll make a difference...

I used a vertical Moxon for 20m in ARRL DX last February and experienced the
same thing. Fortunately was able to keep the feeder almost perpendicular
coming away but the choke balun (a la GM3SEK) made a big difference with
'touchiness'.

I assume without the balun the feeder is, to a greater or lesser extent,
acting as another radiating element and interacting when not at 90deg from
the vertical element. With the balun you just have to worry about induction
on the braid from your dipole, so keep it straight out if possible. Perhaps
a second choke at the tx end?

73,

Stewart, GW0ETF


--- On Tue, 26/7/11, mm0bqi <mm0bqi at blueyonder.co.uk> wrote:

> Set them up in
> the garden yesterday
> and they are very touchy regarding the angle at which the
> coax leaves the
> feed point.  Changes the resonant frequency and
> SWR. 
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