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Old April 5th 04, 01:54 AM
Mike
 
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Looking over the replies to this post makes me wonder where the helpful
ham hand is lurking these days. This poor guy just wants to know about
plans and materials for an antenna to build and all but one reply tells
him he doesn't want one or you should buy this one or he's stupid for
considering one or I can get into this repeater with that antenna, bla,
bla bla. It can be made with the same components as an SO-239 1/4 wave
ground plane but with a little more wire with a cork screw turn at the
bottom. Doesn't anyone have the simple plans for this guy?

George Cronk wrote:

Does anyone know where I can get plans for this antenna? Materials needed
to build one?

Thanks

  #12   Report Post  
Old April 5th 04, 05:21 AM
Howard
 
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On Mon, 05 Apr 2004 00:54:06 GMT, Mike wrote:

Looking over the replies to this post makes me wonder where the helpful
ham hand is lurking these days. This poor guy just wants to know about
plans and materials for an antenna to build and all but one reply tells
him he doesn't want one or you should buy this one or he's stupid for
considering one or I can get into this repeater with that antenna, bla,
bla bla. It can be made with the same components as an SO-239 1/4 wave
ground plane but with a little more wire with a cork screw turn at the
bottom. Doesn't anyone have the simple plans for this guy?

George Cronk wrote:

Does anyone know where I can get plans for this antenna? Materials needed
to build one?

Thanks

Actually I do have plans for a colinear 5/8 over 5/8 2 meter antenna;
all you'd have to do is omit the phasing coil and top radiator. This
one is built from wire on an SO-239.

To the original poster - I can scan the sketch & email it to you, let
me know if you'd like that & it's a done deal.

Howard
KE6something or other
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Old April 5th 04, 08:56 AM
Mark Keith
 
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"Dave VanHorn" wrote in message ...
"Mark Keith" wrote in message
om...
George Cronk wrote in message

. 154.205...
Does anyone know where I can get plans for this antenna? Materials

needed
to build one?

Thanks


You would be better off with a 1/4 wave ground plane on 2m. Seriously.
And one of those can be as simple as five 19 inch pieces of wire and a
So-239 connector. MK


Why would he be better off with a 1/4 wave, with it's large vertical lobe?


Cuz it's easier decoupled with it's 1/4 wave radials, and is less
likely to have feedline radiation than the funky 5/8 antenna with 1/4
wave radials. In direct comparisons here, the 1/4 GP was a good bit
better than the 5/8 with 1/4 radials. The maximum gain of an elevated
1/4 wave GP on 2m, mounted at 35 ft at the base, is appx 6.2 dbi at 3
degrees. The maximum gain of a 5/8 GP with horizontal 1/4 wave
radials, at the same height, is about 4.7 dbi at the same angle. And
this does not yet take into account any decoupling problems! If the
feedline radiates, any gain on the horizon is likely lost as the
pattern is skewed up off the horizon. The average 5/8 antenna is
ruined by using 1/4 wave radials. A 5/8 should be paired with a mirror
image 5/8 to function properly. IE: dual 5/8 collinear such as the
isopole, etc...
And decoupling must still be used even on those. I agree with one
thing Richard said about height and a 1/4 wave..If you get the tip of
the 1/4 GP at the same height as the tip of a tall dual 5/8 collinear,
there is little real difference between the two. And the dual 5/8's
collinear is better than a 5/8 GP. 2m is real critical as far as the
low angles used, and also to the effects of feedline radiation
lowering the gain at those low angles. Now on 10m, many times I do
prefer a 5/8 GP over a 1/4 GP, but there the angles used are less
critical.
If your 5/8's works, I wouldn't worry much, but in comparing them in
A/B tests, "at appx 35 ft" I've never seen a 5/8 GP with 1/4 radials
beat a 1/4 wave GP with 1/4 radials. I once built a fancy 5/8 GP with
a nice larson coil, lots of 1/4 wave radials, etc...Was a super
dud...I tore it up the 1st day and went back to a 1/4 wave. The 1/4
wave was an average 3-4 S units better on local rptrs, and simplex.
About the same difference as comparing a undecoupled ringo ranger, to
a decoupled ringo ranger 2... MK
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Old April 5th 04, 09:07 AM
Mark Keith
 
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Mike wrote in message .com...
Looking over the replies to this post makes me wonder where the helpful
ham hand is lurking these days. This poor guy just wants to know about
plans and materials for an antenna to build and all but one reply tells
him he doesn't want one or you should buy this one or he's stupid for
considering one or I can get into this repeater with that antenna, bla,
bla bla. It can be made with the same components as an SO-239 1/4 wave
ground plane but with a little more wire with a cork screw turn at the
bottom. Doesn't anyone have the simple plans for this guy?


Sure, if he really wants to use an inferior antenna, I can tell him
how to build it. It's simple. A 5/8 wave radiator, and about 4-5 turns
of coil on a one inch form for matching will get him fairly close.
But I don't recommend one. You wouldn't get me running a 5/8 GP on 2m
for anything. It's like G5RV's on 80m...They usually suck...So do most
5/8's GP's on 2m...:/ But don't take my word for it. Compare them with
an antenna switch and see. The only time I ever see a 5/8's beat a 1/4
on 2m, is if they are nearly on the ground. And I think thats just a
line of sight deal... MK
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Old April 5th 04, 04:00 PM
Dave VanHorn
 
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"Mark Keith" wrote in message
om...
"Dave VanHorn" wrote in message

...
"Mark Keith" wrote in message
om...
George Cronk wrote in message

. 154.205...
Does anyone know where I can get plans for this antenna? Materials

needed
to build one?

Thanks

You would be better off with a 1/4 wave ground plane on 2m. Seriously.
And one of those can be as simple as five 19 inch pieces of wire and a
So-239 connector. MK


Why would he be better off with a 1/4 wave, with it's large vertical

lobe?

Cuz it's easier decoupled with it's 1/4 wave radials, and is less
likely to have feedline radiation than the funky 5/8 antenna with 1/4
wave radials. In direct comparisons here, the 1/4 GP was a good bit
better than the 5/8 with 1/4 radials.


Interesting. You obviously have developed a far superior measurement
technique than most antenna engineering firms, and maybe even NIST. Your
results disagree with pretty much everyone who measures antenna gain
professionally, and the ARRL handbooks, but hey they must all be wrong then.

Though it's entirely done in the HF spectrum, a pretty detailed analysis is
presented he
http://www.cebik.com/58-3.html
A good ground, and cleaner near-field space, is easier to come by at VHF and
UHF, so I would expect results to be somewhat better than what was seen here
even at the high end of the HF spectrum.

If you google a bit, you'll probably find some articles on converting a CB
antenna to a 5/8 2 meter antenna.






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Old April 5th 04, 05:21 PM
Tdonaly
 
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Dave VanHorn wrote,
lobe?

Cuz it's easier decoupled with it's 1/4 wave radials, and is less
likely to have feedline radiation than the funky 5/8 antenna with 1/4
wave radials. In direct comparisons here, the 1/4 GP was a good bit
better than the 5/8 with 1/4 radials.


Interesting. You obviously have developed a far superior measurement
technique than most antenna engineering firms, and maybe even NIST. Your
results disagree with pretty much everyone who measures antenna gain
professionally, and the ARRL handbooks, but hey they must all be wrong then.

Though it's entirely done in the HF spectrum, a pretty detailed analysis is
presented he
http://www.cebik.com/58-3.html
A good ground, and cleaner near-field space, is easier to come by at VHF and
UHF, so I would expect results to be somewhat better than what was seen here
even at the high end of the HF spectrum.

If you google a bit, you'll probably find some articles on converting a CB
antenna to a 5/8 2 meter antenna.


In volume 1 of the Antenna Compendium series is an article entitled "The
5/8-Wavelength Antenna Mystique" by Donald K. Reynolds, K7DBA.
I don't think Reynolds would disagree with Mark too much.
73,
Tom Donaly, KA6RUH


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Old April 5th 04, 07:36 PM
Mark Keith
 
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"Dave VanHorn" wrote in message

Cuz it's easier decoupled with it's 1/4 wave radials, and is less
likely to have feedline radiation than the funky 5/8 antenna with 1/4
wave radials. In direct comparisons here, the 1/4 GP was a good bit
better than the 5/8 with 1/4 radials.


Interesting. You obviously have developed a far superior measurement
technique than most antenna engineering firms, and maybe even NIST.


Maybe so if using a simple antenna switch to A/B test is superior...

Your
results disagree with pretty much everyone who measures antenna gain
professionally, and the ARRL handbooks, but hey they must all be wrong then.


No, they do NOT disagree with most who have a clue. BTW, those
"results" I gave you with gain numbers were from modeling.

Though it's entirely done in the HF spectrum, a pretty detailed analysis is
presented he


HF? Thats the problem....You can't apply the performance shown on HF,
and expect it to pan out on 2m. The decoupling problem will rear it's
head on VHF.

http://www.cebik.com/58-3.html
A good ground, and cleaner near-field space, is easier to come by at VHF and
UHF, so I would expect results to be somewhat better than what was seen here
even at the high end of the HF spectrum.


A good ground is not the whole answer. Decoupling is more important at
those higher frequencies.

If you google a bit, you'll probably find some articles on converting a CB
antenna to a 5/8 2 meter antenna.


Why would I need to do that? I already done that before. I've built
enough 5/8 antennas to choke a horse. Maybe two or three. Thats why
I'm fairly comfortable with what I say.
I'd like to ask one question. Have you ever actually compared the two
types at the same time using a switch? MK
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Old April 5th 04, 07:44 PM
Mark Keith
 
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"Dave VanHorn" wrote in message

If you google a bit, you'll probably find some articles on converting a CB
antenna to a 5/8 2 meter antenna.


One note...There is only one case on VHF where I often prefer a 5/8
over a 1/4 , and that is on a car when roof mounted. The 5/8 will
usually "picket fence" less, if you are in an area that is all flat
terrain. But as far as elevated ground planes at the house, I prefer
the 1/4 wave anyday. If I use 5/8 elements at home, it will always be
a dual 5/8 collinear of some type. Not a GP with 1/4 wave radials. MK
  #19   Report Post  
Old April 5th 04, 08:39 PM
Dave VanHorn
 
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"Mark Keith" wrote in message
om...
"Dave VanHorn" wrote in message

If you google a bit, you'll probably find some articles on converting a

CB
antenna to a 5/8 2 meter antenna.


One note...There is only one case on VHF where I often prefer a 5/8
over a 1/4 , and that is on a car when roof mounted. The 5/8 will
usually "picket fence" less, if you are in an area that is all flat
terrain.


And that's exactly where I use them.
Not much problem with ground planes or decoupling.



  #20   Report Post  
Old April 5th 04, 08:47 PM
Vito
 
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Hustler makes a 5/8 wave 2M antenna they call the SF-2. HRO sells them for
$14.95.
At that price the only reason to make one is "for fun" but that's
worthwhile.
73, K3DWW

"George Cronk" wrote in message
54.205...
Does anyone know where I can get plans for this antenna? Materials needed
to build one?

Thanks



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