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Old May 25th 04, 05:53 AM
Dave
 
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Default 1/4 wave vertical vs. loaded vertical

Hi all,

I'm considering putting up a 33' vertical - just 3 sections of Rat Shack
mast (solidly bolted for continuity) plus a 3+/- foot 'adjustable' part
on the bottom to 'trim' the length. Then a bunch of in-ground radials.
40m is my only 'serious' band. 15 meters should be a bonus, right?
Or not?

Would this work better than my 4BTV (which I'll keep for 20 and 10)?
Or would the improvement be so insignificant as to not be worth all
the bother of building the new antenna?

Thanks

Dave WB7AWK


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Old May 25th 04, 09:22 AM
Cecil Moore
 
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Dave wrote:
I'm considering putting up a 33' vertical - just 3 sections of Rat Shack
mast (solidly bolted for continuity) plus a 3+/- foot 'adjustable' part
on the bottom to 'trim' the length. Then a bunch of in-ground radials.
40m is my only 'serious' band. 15 meters should be a bonus, right?
Or not?


Not really. 33 ft. is too long for good 15m performance. The take-off-
angle at the highest gain point is 47 degrees. The free version of
EZNEC at eznec.com will show that.
--
73, Cecil http://www.qsl.net/w5dxp



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Old May 26th 04, 01:24 AM
Mark Keith
 
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Cecil Moore wrote in message ...
Dave wrote:
I'm considering putting up a 33' vertical - just 3 sections of Rat Shack
mast (solidly bolted for continuity) plus a 3+/- foot 'adjustable' part
on the bottom to 'trim' the length. Then a bunch of in-ground radials.
40m is my only 'serious' band. 15 meters should be a bonus, right?
Or not?


Not really. 33 ft. is too long for good 15m performance. The take-off-
angle at the highest gain point is 47 degrees. The free version of
EZNEC at eznec.com will show that.


It will still be quite usable for "average" use. Maybe not as good as
a shorter vertical at low angles, but he wouldn't have trouble making
contacts with it. My 40/17 GP worked pretty well on 15m, despite the
increased average angle of radiation. It was lame as heck on 12 and 10
though...No doubt about it...MK
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Old May 25th 04, 12:40 PM
Dale Parfitt
 
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"Dave" wrote in message
news.com...
Hi all,

I'm considering putting up a 33' vertical - just 3 sections of Rat Shack
mast (solidly bolted for continuity) plus a 3+/- foot 'adjustable' part
on the bottom to 'trim' the length. Then a bunch of in-ground radials.
40m is my only 'serious' band. 15 meters should be a bonus, right?
Or not?

Would this work better than my 4BTV (which I'll keep for 20 and 10)?
Or would the improvement be so insignificant as to not be worth all
the bother of building the new antenna?

Thanks

Dave WB7AWK

Should be fine on 40M. Although the match might be decent on 15M, the high

takeoff angle will not be good for 15M DX.

Dale W4OP


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Old May 26th 04, 12:26 AM
H. Adam Stevens
 
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"Dale Parfitt" wrote in message
...

"Dave" wrote in message
news.com...
Hi all,

I'm considering putting up a 33' vertical - just 3 sections of Rat Shack
mast (solidly bolted for continuity) plus a 3+/- foot 'adjustable' part
on the bottom to 'trim' the length. Then a bunch of in-ground radials.
40m is my only 'serious' band. 15 meters should be a bonus, right?
Or not?

Would this work better than my 4BTV (which I'll keep for 20 and 10)?
Or would the improvement be so insignificant as to not be worth all
the bother of building the new antenna?

Thanks

Dave WB7AWK

Should be fine on 40M. Although the match might be decent on 15M, the

high
takeoff angle will not be good for 15M DX.

Dale W4OP

I use a Fluidmotion BiggIR vertical on a 3500 ft^2 aluminum roof. The house
is on a hill in the country.
Works great on 40. I really like it. The DX at 3AM (that is just not there
on a dipole) is LOUD.
I can use it as a 3/4 or 1/4 on 15 and can't tell much difference.
Sometimes one is better, sometimes the other. Propagation can be complex.
Nice to be able to push a button and see which is best.
73
H.
NQ5H




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Old May 25th 04, 02:34 PM
'Doc
 
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Dave,
Depending on if the 'old' vertical covered 40 meters at
all, the 'new' vertical might be an improvement. But not
really 'much' of one, there may be no practical difference
in performance on 40 meters.
Would 15 meters be a bonus? If you mean an unexpected
improvement over the 'old' vertical, then, no, the 'old'
vertical probably would work better on 15 meters.
If you don't have the "bunch of in-ground radials" already
in the ground, put them in and then put the 'old' vertical over
them! I think you'll see a greater over-all improvement that
way, rather than with just the 'new' vertical (except on
40 meters, maybe).
"Full sized" antennas work 'better' than 'shortened'
antennas,
in general, but sometimes that 'better' is sort'a hard to hear.
'Doc
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Old May 26th 04, 01:28 AM
Mark Keith
 
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Default

"Dave" wrote in message tnews.com...
Hi all,

I'm considering putting up a 33' vertical - just 3 sections of Rat Shack
mast (solidly bolted for continuity) plus a 3+/- foot 'adjustable' part
on the bottom to 'trim' the length. Then a bunch of in-ground radials.
40m is my only 'serious' band. 15 meters should be a bonus, right?
Or not?

Would this work better than my 4BTV (which I'll keep for 20 and 10)?
Or would the improvement be so insignificant as to not be worth all
the bother of building the new antenna?

Thanks

Dave WB7AWK


It'll be better on 40m. No doubt. Hard to say on 15, but you might be
surprised. I don't think it would be quite as bad as some forecast.
For average use anyway.
You might consider 17m as a 5/8 wave. Easily matched with a series
loading coil at the base. Of course, you would want to take it out for
40m, unless you want to be tuned at 6.9 mhz...:/ I used a 24 volt
relay to switch on one antenna I used. MK
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