[UK-CONTEST] CQWW CW QRP 7MHz

[Steve Knowles]

Gordon

The antenna sounds like a variety of what used to be called a 'half-bobtail' 
(2 x 1/4wave verticals 1/2wave apart) except that in the classic 
configuration they're connected together at their tops and one is fed at the 
base against earth (OK with QRP but decidedly dicey with higher power!).  I 
used one myself for many years and they are VERY good but they are 
vulnerable in a noisy environment, which is why I moved to a loop.

Without knowing more details of Barry's antenna, particularly the ground 
arrangements, and without details of the receiving antenna(s) and relative 
paths length/directions, I would say it's impossible to make any meaningful 
comparisons.  Also, the figure quoted is S/N rather than absolute strength. 
W6EL estimates the principal wave angles at the relevant times for both 
stations to ES as 13degrees, for G-DL as 21degrees and for GM-DL as 
10degrees.  These are low for a horizontal dipole and the vertical could be 
expected to do very much better than +4db, particularly if the receiving 
antenna is also a vertical.

73

Steve
G3UFY


----- Original Message ----- 
From: "Gordon Brown" <gordonbrowns at btinternet.com>
To: <uk-contest at contesting.com>
Sent: Tuesday, November 30, 2010 3:13 PM
Subject: Re: [UK-CONTEST] CQWW CW QRP 7MHz


I guess we are all looking at ways of improving our signal and I was so
impressed by the GM3YEH QRP score that I thought I would have a look at the 
half
square antenna he uses. It seems to be a pair of top fed quarter wave 
verticals
fed in phase and some people claim it gives up to 4dB gain over a dipole at 
low
radiation angles. My next step was to see how Barry's signal compared to 
mine
on the air and I used reverse skimmer to get the following results -
Rx Stn Tx Stn freq S/N speed
time date
ES5PC GM3YEH 7012.6 CQ 23 dB 25 wpm 1048 28
ES5PC G1N 7010.0 CQ 24 dB 25 wpm 1050 28
DL2CC GM3YEH 7012.7 CQ 20 dB 26 wpm 1051 28
DL2CC G1N 7010.1 CQ 26 dB 25 wpm 1052 28
ES5PC GM3YEH 7012.7 CQ 14 dB 25 wpm 1059 28
ES5PC G1N 7010.0 CQ 24 dB 25 wpm 1100 28

These were the only anywhere near meaningful comparisons I could find
I was running 110 watts to a dipole which should give me about 16dB over 5 
watts
and give him 4dB with the half square over my dipole making an overall
difference of 12 dB in my favour. I guess I don't have enough information to
allow for the different paths but it looks like the GM3YEH half square is 
much
better than I thought it was.
73
Gordon.

----- Original Message ----- 
From: "GM3YEH" <gm3yeh at googlemail.com>
To: <uk-contest at contesting.com>
Sent: Monday, November 29, 2010 8:57 PM
Subject: [UK-CONTEST] CQWW CW QRP 7MHz


> I've never been much of a QRP fan, but I decided to give it a go for the
> 2010 RSGB 80m sprint series and was astonished with the results. This
> encouraged me to think about a QRP effort for this year's CQWW CW. I only
> use wire antennas and can just get one up in my garden at a time so I
> decided on something with a bit of gain for a single band 40m entry. A
> half
> square was decided on with main lobes towards the east and west. I got it
> up
> and tested just before the snow started. One of the most impressive
> things
> I noticed over the weekend was the high proportion of Ws who managed to
> copy
> my tiny wee 5W signal on the first call - lots of those guys have really
> great ears. A lot of time was spent on repeats and my callsign was
> regularly mis-copied as GM3YES - which is a real pain in the neck after
> the
> other guy gives his TU and I need to call him again with the correction.
> Although I probably wouldn't be patient enough to use QRP all the time, it
> was a nice change - especially getting into VK! I didn't work GM or GI.
>
> Points - 127,568
> QSOs - 721
> Zones - 21
> Countries - 91
>
> 73 de Barry GM3YEH.
> _______________________________________________
> UK-Contest mailing list
> UK-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/uk-contest

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