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Philuk
Junior Member
Username: Philuk
Post Number: 35
Registered: 4-2009
| | Posted on Friday, August 17, 2012 - 3:29 pm: | 
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Hi and thanks for reading.
I have been playing around with home brew version of a comercial vertical 25-30mhz antenna which includes a TX capacitor and a coax matching shunt, this antenna when laying horizontal across my antenna rests at a hight of aprox 6ft above ground in the garden receives exceptionly well (best antenna Ive tried yet!) and has a reasonable swr but as soon as I erect it vertical the swr shoots up from 1.6:1 to above 3 and it becomes as deaf as a post, all connections are sound and it is not the matching stub as even clipped to the main antenna element nothing changes?
Can anybody explain this please?
see the antenna plans here
http://photobucket.com/Homebrewantenna
cheers
Phil
M6MRP Yaesu FT817nd, FT840 FT51R.
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Tech833
Moderator
Username: Tech833
Post Number: 2190
Registered: 8-2002
| | Posted on Sunday, August 19, 2012 - 12:08 pm: |
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According to your picture, it is essentially a Gainmaster.
Having the antenna 6 feet above ground and horizontal will drastically change the way it tunes. If you get it tuned like that, then erect it vertically, the tuning will be off by a lot.
Best bet is to tune the antenna with it in the vertical plane, possibly hanging by something (maybe a tree limb?).
You mentioned that with it just 6 feet above ground and horizontal, quote: "best antenna Ive tried yet!".
If that is the case, why not just leave it as-is where you had favorable results?
Your radio 'Mythbuster' since 1998
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Tech237
Moderator
Username: Tech237
Post Number: 1608
Registered: 4-2004
| | Posted on Monday, August 20, 2012 - 9:01 am: |
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What Tech833 says x 2
Tech237
N7AUS
God made me an athiest, who are you to question his wisdom?
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Philuk
Junior Member
Username: Philuk
Post Number: 38
Registered: 4-2009
| | Posted on Monday, August 20, 2012 - 5:35 pm: |
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Thanks guys, Ive tried leaving it where it is but the xyl is not impressed as usual, no trees here in this very small garden so its a pain in the backside trying to tune a vertical in free space, I have not been trying to tune it lying horizontal just noticed that when it was in that possition it was working good? I thought it may be working as a type of NVIS antenna and the ground having some strange effect on it? yes it is based on the gain master and I have wasted so much time on the dam thing I have decided to bite the bullet get some cash together and buy one! something else for the xyl to gripe about hihi.
thanks again
Phil
M6MRP Yaesu FT817nd, FT840 FT51R.
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