How do YOU tune a Maco V58?
Bruce Bennett
I remember some time ago the talk about setting the overall length of a V58
to 222" tip to tail. I tried that. It seems you are almost removing about a
1/8 of a wave! Anybody got a close match at 27.205 with the factory setting?
This assumes you mount the antenna at least +18 feet. Have you gotten
the gamma match to flatten out the swr on either end of the band?
Obviously, I'm not at all happy yet with the proformance I'm getting with the
V58 but I still haven't convinced myself it's the antennas fault!
If I can get a good match I'm going to run some A/B tests between it and
a A99. Interested?
George Warner
In article <Bruce.Bennett...@tek.com>, Bruce....@tek.com
(Bruce Bennett) wrote:
I installed one a few months back. It ended up to be 229" top to
bottom even though the instructions suggest around 239".
The length is the primary adjustment; it sets the center frequency
of operation. The ring has a much smaller effect but it will get the
match down to virtually 1:1 at the center frequency.
The recommended length (about 239") is 0.55 wavelengths.
The length that works (about 229") is 0.52 wavelengths.
So, you are not removing 1/8 of a wave; it was never there!
This raises a different question: how can they call it a
5/8 wave antenna? I do not know this answer.
You can do a DejaNews search to see what else was said
about this antenna. It was a pretty lively thread.
The antenna performs very well.
George Warner
warn...@loveboat.com
SHORT CIRCUIT
I have not seen or used the Maco 5/8, if it has a capacity hat on the
vertical part of the antenna, this will shorten the length needed to
make it a 5/8 wave antenna. A capacity hat is a few pieces of aluminum,
usually, which are near the upper part of the vertical. Some people
like to call them "radials" and it is a good way to shorten antennas.
George Warner
SHORT CIRCUIT <so...@not.today> wrote:
It has no such hat.
George
Al Trainer
Bruce Bennett wrote:
>
> I remember some time ago the talk about setting the overall length of a V58
> to 222" tip to tail. I tried that. It seems you are almost removing about a
> 1/8 of a wave! Anybody got a close match at 27.205 with the factory setting?
> This assumes you mount the antenna at least +18 feet. Have you gotten
> the gamma match to flatten out the swr on either end of the band?
>
> Obviously, I'm not at all happy yet with the proformance I'm getting with the
> V58 but I still haven't convinced myself it's the antennas fault!
>
> If I can get a good match I'm going to run some A/B tests between it and
> a A99. Interested?
A friend just bought a maco 5/8 and in the installation it recommends
240 inches as total length. I know of alot of people that have some of
the old penetrator ground planes around due to the fact they cannot
remember the radiator length of the antennae. They are still sitting out
there unused.
AL
DBiz
Bruce Bennett wrote:
> I remember some time ago the talk about setting the overall length of a
V58
> to 222" tip to tail. I tried that. It seems you are almost removing
about a
> 1/8 of a wave! Anybody got a close match at 27.205 with the factory
setting?
> This assumes you mount the antenna at least +18 feet. Have you gotten
> the gamma match to flatten out the swr on either end of the band?
> Obviously, I'm not at all happy yet with the proformance I'm getting
with the
> V58 but I still haven't convinced myself it's the antennas fault!
> If I can get a good match I'm going to run some A/B tests between it and
> a A99. Interested?
I also assembled my V5/8 to spec and found that it was tuned to the low
end of the band. I wanted it tuned to the higher side of the band. First I
supported the
antenna horizontaly on the roof using a wooden hourse and my chimminy.
Then I tried to tune it using the gamma ring connection. This didn't do
too much. So I shortened the antenna a total of about 10 to 15"! Before I
got
the match the way I wanted it. This was accomplished by telescoping in
each of the vertical sections equeally. When I got everything set. I
drilled a small pilot hole in the gamma ring and used a self tapping screw
to hook up the ring terminal to the gamma ring. I also got rid of all
those clamps that hold the elements in place and used hose clamps instead.
My antenna is tuned 1.1:1 on channel 38 and is 1.3:1 on chanel 1. It also
tunes well into the upper freqs. Also higher up you get it the better it
performs.
Good luck with it. And if you run some A/B tests between it and a A99 I'm
Interested?
David Bizon
e-mail--------> db...@aol.com
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AL7KB
I brief discussion of antenna design should help you understand why a
Maco 5/8 is "shorter than a full 5/8. The capacity hat on the vertical
creates lumped capacitive reactance, this allows the antenna to be
shorter than what you would get from the classic formula for calculating
the length of a 5/8 wave vertical. A capacity hat shortens an antenna
by a factor roughly equal to twice the diameter of the hat.
Example, a vertical has a capacity hat 2 feet wide. You can build the
antenna about 4 feet shorter, with the same resonant frequency and
feedpoint impedance.
This is a very simplified description, minus a lot of the technical BS
at play with antenna design. Read up on antenna theory to learn more.
ks4...@gmail.com
> I remember some time ago the talk about setting the overall length of a V58
> to 222" tip to tail. I tried that. It seems you are almost removing about a
> 1/8 of a wave! Anybody got a close match at 27.205 with the factory setting?
> This assumes you mount the antenna at least +18 feet. Have you gotten
> the gamma match to flatten out the swr on either end of the band?
>
> Obviously, I'm not at all happy yet with the proformance I'm getting with the
> V58 but I still haven't convinced myself it's the antennas fault!
>
> If I can get a good match I'm going to run some A/B tests between it and
> a A99. Interested?