[UK-CONTEST] 20m vertical

[Danny Higgins]

If you are worried about F/B on receive, why not use a separate RX loop 
antenna with a rotatable null.  If you can get a bit of separation 
between the antennas you may even be able to use a second receiver to 
find multipliers while you are CQing.

Danny, G3XVR

Callum M0MCX wrote:
> James, I can tell you've been off with the flu :). Yes, the 40m vertical
> array was rather special and gave us a 10 hour pile-up from Dorridge.
> Unfortunately it's not rotatable, as you say!
>
> Mark,
>
> I thoroughly recommend a vertical for playing with, certainly most excellent
> for 40m - you'll love it down there. Try a loaded version for 80m too if you
> like. Spiderbeam do a 12m mast (and an 18m version too which will tune on
> 80m by lengthening the radials a whisker). You can't get it wrong being so
> close to salt water. 10m fishing poles can be bought for less than 30 pounds
> so there's no excuse for not buying a pair. Initially, for 20m, go down the
> route of using a pair of radials about a meter above the ground (that's the
> feedpoint raised up a bit) and you'll find a near match to 50 ohms. Very
> convenient. You may find it'll be excellent for general DX. But as James
> says, you won't have any front-to-back ratio and the EU lot will bombard you
> when you're trying to work the US etc. so as a contest antenna it won't be
> so good however Tim (M0URX) worked 100 countries on 40m during CQWW with a
> basic quarter-wave. Build one!
>
> Here's pictures of a 40m vertical done on the cheap with a 10m fishing pole
> at 3m above the ground using 4 radials sloping to about 50cms above ground
> (although a pair should act the same. 4 looked better!). You can use a
> dipole centre from Moonraker / W&S etc as the feepoint. Clamp some ferrites
> on the coax to act as a type of balun by the feedpoint to be more pure. This
> will deliver you a more accurate piece of research.
>
> - http://www.m0mcx.co.uk/gallery/picture.php?/460/category/41
>
> Build both and let us know how they worked..??!!
>
> (and here's a yagi version:
> http://www.m0mcx.co.uk/gallery/picture.php?/458/category/41 - difficult to
> rotate as you say!!) 
>
> Cheers,
>
> Callum McCormick
> http://www.m0mcx.co.uk/
>
>
> -----Original Message-----
> From: uk-contest-bounces at contesting.com
> [mailto:uk-contest-bounces at contesting.com] On Behalf Of James Thresher
> Sent: 12 November 2008 16:05
> To: uk-contest at contesting.com
> Subject: Re: [UK-CONTEST] 20m vertical
>
> This was a 1/4 wave vertical with 4 radials, and another slightly larger 1/4
> vertical (not driven in any way) acting as a reflector, again with 4
> radials, they were about a 1/4 wave apart. It wasn't just a vertical yagi ;)
> It was built for 40m so it was quite large, the modelling suggested pretty
> good gain figures. We had planned to build a 4 or 5 element version for SSB
> Field day this year but decided against it in the end. Not sure how you
> would even get the 2 element version rotating on a mast complete with
> radials.
>
> 73
>
> -----Original Message-----
> From: uk-contest-bounces at contesting.com
> [mailto:uk-contest-bounces at contesting.com] On Behalf Of Ian Maude
> Sent: 12 November 2008 15:53
> To: UK-Contest
> Subject: Re: [UK-CONTEST] 20m vertical
>
> James Thresher wrote:
>   
>> We've actually played around with these, a couple of the others in our
>>     
> club built one the other year for 40m, they had pretty good results with it.
> The big disadvantage of course is that you can't rotate it.
>   
> Why ever not?  If you mount it as ours was on 1 mast, it rotates easily :)
>
> 73 Ian
>
> --
>
> Ian J Maude, G0VGS
> SysOp GB7MBC DX Cluster
> Member RSGB, GQRP
> K2 #4044 |K3 #455
> http://www.amateurradiotraining.org
>
> _______________________________________________
> UK-Contest mailing list
> UK-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/uk-contest
> _______________________________________________
> UK-Contest mailing list
> UK-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/uk-contest
>
> _______________________________________________
> UK-Contest mailing list
> UK-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/uk-contest
>
>
>