Info on the Gaun Master type antenna's

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ian
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Info on the Gaun Master type antenna's

Post by ian » 13 May 2015, 14:05

Hi I'm looking for info on my Gain Master type antenna's can someone tell me of any wedsites, I have looked on the net and books but all I find are all about the Gain Master I know it a sleeve dipole type but that's all, can someone point me in the right direction cheers.
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Re: Info on the Gaun Master type antenna's

Post by cjay » 13 May 2015, 15:19

There's a *long* thread on here about homebrewing a gainmaster. That should answer most if not all your questions but be prepared, there's lots to read.

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Re: Info on the Gaun Master type antenna's

Post by Mark-in-Essex » 13 May 2015, 17:30

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ian
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Re: Info on the Gaun Master type antenna's

Post by ian » 13 May 2015, 19:01

Thanks for your help but I'm not actually looking for info on the gain master itself but on the type of ariel it originates from, I don't think I worded my question right the first time, I've read a few of the threads on here and got some good info on it cheers.
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Re: Info on the Gaun Master type antenna's

Post by RadioPixie » 13 May 2015, 19:18

It's an Off Centre Fed Dipole that is 5/8 wavelength with a matching stub and a RF choke for the common mode currents along the down feed from the matching stub. So it's very similar to a Carolina Windom antenna (even though it has a wide band 4:1 balun instead of the narrow band matching stub used in the GM), but the lower section of the Gaun Master is coax, so similar in that respect to a Bazooka or T2TL.

If the Gaun Master was an horizontal wire antenna and you didn't need it to be fed with coax at one end (so the matching stud with the feeder dropped vertically down from the feed point), it would be more textbook recognisable and wouldn't be such a mystery!
Last edited by RadioPixie on 13 May 2015, 21:01, edited 1 time in total.
73 from Dave the Pixie - 26CT052 - G7OPC - CB & Ham Radioaficionado

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Re: Info on the Gaun Master type antenna's

Post by ian » 13 May 2015, 19:48

Thank for your info this is exactly what I was looking for cheers buddy
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Re: Info on the Gaun Master type antenna's

Post by Maple » 13 May 2015, 21:26

Actually the Gain-Master is a center fed vertical dipole with 0° (horizontal) radiation angle which is perfect for DX and long range communication.
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Re: Info on the Gaun Master type antenna's

Post by RadioPixie » 13 May 2015, 22:10

Actually you're probably right because as the radiation angle from a vertical OCFD would be more elevated above 0', but as Sirio suggests all the currents are in phase (unlike a conventional 5/8w) :oops: So would that then mean that it works more like a collinear? Sorry Ian I should engage thy brain before typing. I think it's more like a collinear and is similar to a 7/8w mobile whip as used on 2m band which is an in-phase antenna.

Happy to learn from my mistakes :D
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Re: Info on the Gaun Master type antenna's

Post by wa10 » 14 May 2015, 11:05

Don't be fooled by sirio's fancy advertising, gainmaster's don't have a 0 degree takeoff angle when mounted over real earth at typical antenna heights,
freespace plots look nice on paper but its not what you end up with when you stick it on a pole in your back yard.

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Re: Info on the Gaun Master type antenna's

Post by RadioDaze » 14 May 2015, 11:07

I use the Gain Master and I like it. I am not sure about the performance claims yet and have had it about 3 months and being using it mobile static. For some reason I can only get a SWR of 1.5 or 1.6 : 1 whereas my 1/2 wave silver rod goes 1.1 : 1 with ease. I am going to try and test the Silver Rod out in similar conditions in weeks to come. As I change location it is more difficult to get a like for like impression against other verticals.

In saying this (and it might have happened with another antenna) my longest distant contact was to Indonesia and using the Gain Master.
I am trying to base performance considerations on long distance UK point to point line of sight / ground wave contacts. It is a work in progress.

Whatever it does the job well and in my mind is one of the top 3 performing vertical 5/8 length antennas in existence.

They work well but that will be a relatively small performance increase relative to other good 5/8 wave length antennas.

Some report 6dB differences (that is a lot for just an antenna change and much more bang for buck than going from 100W to around 500W which is what you need to get a similar gain increase) 1 S point.

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Re: Info on the Gaun Master type antenna's

Post by RadioPixie » 14 May 2015, 14:29

wa10 wrote:Don't be fooled by sirio's fancy advertising, gainmaster's don't have a 0 degree takeoff angle when mounted over real earth at typical antenna heights,
freespace plots look nice on paper but its not what you end up with when you stick it on a pole in your back yard.
The reality is that most antennas find it difficult to achieve their theoretical potential. Living in the real world is a bit different. But stick to my last statement that it's functioning as a collinear unless somebody prove otherwise. After all isn't the capacitor for phasing?
Last edited by RadioPixie on 14 May 2015, 16:13, edited 1 time in total.
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Re: Info on the Gaun Master type antenna's

Post by RadioPixie » 14 May 2015, 16:06

RadioDaze wrote:I use the Gain Master and I like it. I am not sure about the performance claims yet and have had it about 3 months and being using it mobile static. For some reason I can only get a SWR of 1.5 or 1.6 : 1 whereas my 1/2 wave silver rod goes 1.1 : 1 with ease. I am going to try and test the Silver Rod out in similar conditions in weeks to come. As I change location it is more difficult to get a like for like impression against other verticals.

In saying this (and it might have happened with another antenna) my longest distant contact was to Indonesia and using the Gain Master.
I am trying to base performance considerations on long distance UK point to point line of sight / ground wave contacts. It is a work in progress.

Whatever it does the job well and in my mind is one of the top 3 performing vertical 5/8 length antennas in existence.

They work well but that will be a relatively small performance increase relative to other good 5/8 wave length antennas.

Some report 6dB differences (that is a lot for just an antenna change and much more bang for buck than going from 100W to around 500W which is what you need to get a similar gain increase) 1 S point.
The GM should be better SWR than that on 27MHz, but it's easy to get paranoid about SWR, it's a mental health issue ;)

It's doubtful that the typical s-meter on any rig goes in 6dB steps. More like 3dB in many cases. Even expensive HF rigs have poorly calibrated s-meters. Thus making judgements difficult.

As for apparent performance increase and decrease of a 1/2 or 5/8w antenna, this is hard to tell as there are so many variables, some of which are mast and coax length, soil conductivity, propagation at that moment in time and so forth.

But I like the GM, set it up and plug n play. Job done. No need to add a RF choke, no radials, no tuning, good performance, good bandwidth for CB/10m, all good stuff :thumbup: But i think the OP just wishes to know the origins of the design.
73 from Dave the Pixie - 26CT052 - G7OPC - CB & Ham Radioaficionado

RadioDaze

Re: Info on the Gaun Master type antenna's

Post by RadioDaze » 14 May 2015, 16:25

Well you have to have some kind of reference point and I understood 6dB to be the starting point between S point readings otherwise we will just say anything and that is not much help. I have had to jig my G Master about for portable work and that may have a slight effect on the SWR. I put a very fine/light fishing rod up and tape the wire up that after gaffering the rod to the lower fibre glass section. It could be it does not stretch the wire quite like the original fibre glass and brass inserts make it stretch. Or it might be that the fishing rod makes a little difference. Weird as it SWR'd 1.3:1 when I first got it and there is no way water has got into the bottom section.

I still like the antenna but would like to do some other tests with the Silver Rod and try and build up a picture over weeks and months. This should provide a better guidance of performance for my own ways of operating. Everyone's situation is unique.

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Re: Info on the Gaun Master type antenna's

Post by RadioPixie » 14 May 2015, 16:43

Well you have to have some kind of reference point and I understood 6dB to be the starting point between S point readings otherwise we will just say anything and that is not much help
Yes very true for any technical and scientific measurement, but unfortunately the majority of radios with s-meters are NOT calibrated to a meaningful standard. For years people have been giving reports that in terms of actual signal strength that are meaningless. Just listen to the 5'n'9 reports that is continuously quoted. And if every body is 5'n'9 then it isn't worth quoting. A collection of meaningless data.The first figure is qualitative readability report any case. If you are interested there is an article recently in the May 2015 Practical Wireless that explains this subject well.

Unless calibrated, s-meters are just qualitative devices to give an idea of what's going on with reception, a useful guide and no more.
Last edited by RadioPixie on 14 May 2015, 19:00, edited 1 time in total.
73 from Dave the Pixie - 26CT052 - G7OPC - CB & Ham Radioaficionado

RadioDaze

Re: Info on the Gaun Master type antenna's

Post by RadioDaze » 14 May 2015, 17:49

Other than your ears it is all you have so it's value is not negated. If you just had ears it would be even worse. A consistent 1S point up on a Gain Master (or other Quality antenna : Insert model here ...........) across a wide variety of S meters would average as a 4.5dB increase then. You going to have to push a lot of extra watts upwards from 100 Watts to get 4.5 dB upward swing on a meter.

To my mind it still makes antenna induce meter swing pound for pound better value than electrically produced RF energy.

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