[UK-CONTEST] CQWW SSB 10m SO Unassisted : G3ZQH

[Darren Collins (G0TSM)]

The lower noise floor on the 4 ele Yagi is due to it's better F/B, 
narrower forward lobe but mainly due to the lack of side nulls on the 
Hexbeam.

Clive is right, If you hear Mike SED on the higher bands then you may 
know he uses an optibeam, but with only 2 elements on 10M (actually 2 
elements on all 5 bands) but its up at 75ft. Mike is only 9 miles away 
and we are always comparing with stations at the other end. On 10M Mike 
is neck and neck with my 5 ele @45ft on 90% of the stations. 
Unfortunately planning restrictions, a 21ft wide garden, and overhanging 
tree branches limit what I can do here so the 5 ele is the biggest 
antenna I can get up for 10M for my everyday DXing, the problem when 
using that in a contest is the narrow forward lobe, deep side nulls and 
25dB F/B. When beaming to the West Eastern Eu can be barely readable but 
swinging the beam round they can be 9+. Great for point and shoot, not 
so good for multiplier hunting. I have a dipole at 90deg on the sub Rx 
which helped in CQWW but I need to dig out my 10M 5/8 vert which is 
corroding in the grass somewhere, that is a more effective mult finder.

Darren G0TSM

On 30/10/2012 13:39, Clive GM3POI wrote:
> Forget about minor differences in alleged gain of the different antennas, and think in terms on Wave angle required at the wanted frequency. For example 10m is roughly half the angle of that required at 20m typically often below 5 degrees. This is the only real DX performance to worry about, fractions of a db are meaningless. Far better to have a 2el 10m yagi at 70ft than a 6el at 30ft and you can make a 2el 10m yagi for next to nothing.
> 73 Clive GM3POI
>
> -----Original Message-----
> From: UK-Contest [mailto:uk-contest-bounces at contesting.com] On Behalf Of G3ZQH
> Sent: 30 October 2012 07:52
> To: uk-contest at contesting.com
> Subject: Re: [UK-CONTEST] CQWW SSB 10m SO Unassisted : G3ZQH
>
> Thanks for info on hexbeam vs Yagi.  Interesting that the noise level was lower with the Yagi- possibly as a result of the higher angle lobe that appears on the hexbeam at around 50’ height.
>
> I have pasted in a table I put together a couple of years ago when I was looking for best value for a 5-band directional antenna. It is interesting to see that with these inevitably compromised antennas there is generally fairly poor performance on 10m particularly F/B ratio. The SteppIR in 2- or 3-el format is actually worse than the hexbeam on 10m F/B!
>
>   
>   
> SteppIR 3 el
> SteppIR 2 el
> Optibeam 10-5
> G3TXQ hex
> Spiderbeam
> Max. Element length (m)
> 10.97
> 10.97
> 7,70
> 6.6
> 10
> Boomlength (m)
> 4.9
> 1.44
> 3.75
> 6.6
> 10
> Turning Radius (m)
> 6
> 5.61
> 4.3
> 3.3
> 5
> Weight (kg)
> 19
> 13.6
> 14
> 10
> 11.5
> Windload (sq ft)
> 6.1
> 4.0
> 3,2
> 6.0
> 3.8
> Gain dBd 20
> 4.9
> 4.2
> 4.2
> 3.8
> 4.5
> Gain dBd 17
> 5.5
> 4.2
> 4.4
> 3.2
> 3.2
> Gain dBd 15
> 5.7
> 4.1
> 4.2
> 3.5
> 4.7
> Gain dBd 12
> 6.2
> 4.0
> 4.4
> 3.0
> 3.0
> Gain dBd 10
> 6.3
> 3.8
> 4.8
> 3.6
> 4.9
> F-to-B dB 20
> 21
> 18
> 22
> 22
> 15
> F-to-B dB 17
> 20
> 19
> 17
> 19
> 20
> F-to-B dB 15
> 27
> 13.7
> 15
> 16
> 20
> F-to-B dB 12
> 21
> 13
> 15
> 13
> 10
> F-to-B dB 10
> 11
> 9.3
> 20
> 16
> 18
> Price £
> 1500
> 1100
> 1000
> 500
> 450
>   
>
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