[UK-CONTEST] What anuk-contest@contesting.com <uk-contest@contesting.com>tenna for AFS?

[col]

 i vaguely remember a couple of years ago clive gm3poi did an analysis of 
AFS test propagation from GM and suggested that we would need a 3 el yagi @ 
180' to be competitive from up here!

We thought the wire reflector did help, but that is subjective. i have 
looked at wire yagis but dont think we can get them up high enough to make 
them worth the effort. i do like the look of the 80m moxon cebik describes 
might be worth a try if you have a small garden.

 One of the best all round antennas we have used from GM6NX on 80m was a 
full size quad loop fed 1/3 wavelength up one side chapter 10-6 on4un 
lowband dxing

i think geoff has got it right with a inverted L easy to make with a fishing 
pole for vert section and feed with a 2:1 unun, couple of elevated radials, 
works every time takes minutes to put up.

Talking of wide band noise I wish I could cure my s9+++ constant noise at 
this QTH from 1.8-30mhz noise dies down a bit above 21 mhz to s5. Have tried 
to locate but to no avail its not in my house or immediate neihbours turned 
all electricity off to test.

it has a spike every 50-100 khz wibeband i suspect its a switch mode power 
supply. The noise never dissapears 24/7, vhf frequencies clear.

Is it worth asking ofcom to have a look as it does interfere with am 
reception?


regards Colin


----- Original Message ----- 
From: "G3SJJ" <g3sjj at btinternet.com>
To: "col" <col at v21mail.co.uk>
Cc: <uk-contest at contesting.com>
Sent: Monday, January 02, 2006 6:24 PM
Subject: Re: [UK-CONTEST] What antenna for AFS?


> Be interesting to know if you actually noticed the 0.1dB gain!!  Seriously 
> though, might be worth trying to calculate what take off angle is required 
> to put maximum signal into say Berkshire from a location in central 
> Scotland and then designing the 2 el array spacing for that.
>
> What I find interesting about that article, which John LZQ sent me a 
> couple of years ago, is that for "good" ground my antenna at 55ft is very 
> close to the optimum height for max NVIS gain, and for "very good" ground 
> it is a few feet too high. I would class the heavy clay soil around here 
> as "Good to Very Good." My AFS/80m Cums results over the last few years 
> appear to verify this.
>
> We came to the conclusion that a parasitic reflector would not have any 
> major effect, although I am tempted to try a 140ft wire apex about 15ft, 
> sloping to about 5ft to mimic the slope characteristic of the driven 
> element.
>
> Interestingly I notice on 160m that the dipole (which is the 80m dipole 
> with 60ft extensions on each leg, jumper dissed for 80m) always performs 
> similar to dipoles 15 to 20 higher at other locations. Again I have put 
> this down to local ground conductivity and that it is uninterrupted for 
> many wave lengths.
>
> Chris G3SJJ
>
>
> col wrote:
>
>>Hi Stewart HNY
>>
>>have a look at w4rnl's site lots of info on NVIS antennas for 80m
>>http://www.cebik.com/wire/cb.html
>>
>>John mm0ccc and I used the 2 el wire yagi firing straight up approach at 
>>gm6nx
>>
>>Colin GM0RLZ
>>----- Original Message ----- 
>>From: "Cooper, Stewart" <coopers at odl.co.uk>
>>To: <uk-contest at contesting.com>
>>Sent: Monday, January 02, 2006 3:31 PM
>>Subject: [UK-CONTEST] What antenna for AFS?
>>
>>
>>
>>>HNY contesters! AFS is only a few days away, and I wondered what antenna 
>>>would be best? I have a vertical and a delta loop. Perhaps I ought to put 
>>>up a dipole? Last year my crappy old dipole seemed to perform the best as 
>>>I recall.
>>>
>>>Stewart
>>>GM4AFF
>>>
>>>P.S. Perhaps the dipole ought to be in Oxfordshire, but that's another 
>>>matter.
>>>
>>>
>>>
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