[UK-CONTEST] Vertical Dipole

[Stewart Rolfe]

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.