OK, after the thread on PL-259 losses, I figured
my system (ant gain - connector losses - coax loss)

150 mhz total net gain 1.006 DBi
450 mhz total net gain 2.797 DBi
Antenna tip is 32'6" above ground

My proposed system would replace the RG 58 coax pieces
with a single section of Flexi 4XL and the antenna would
be a Comet GP-9. The new figures a

150 mhz total net gain 7.919 DBi
450 mhz total net gain 10.553 DBi
Antenna tip is 47'6" above ground

150 mhz = 6.913 db improvement
450 mhz = 7.756 db improvement
Antenna tip 15 feet higher

Cost - about $250 for the improvement.

Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.


Ken KG0WX

Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.

Well, a 6 dB boost would double your range, IF you aren't hitting the limits
imposed by your radio horizon. VHF and UHF don't "bend" much, so once you go
beyond your radio horizon, you're pretty much done, no matter how much
signal you had. It will improve your signal into repeaters, where you were
a little noisy before, you should be quiet. On simplex, you'll notice
better signal once you get far enough away that you used to be no longer
full quieting.

In an FM receiver, there is a signal limiter, that caps the signal level, so
if you were already "full quieting", then no amount of power increase would
result in a better signal. If you are far enough away that you're not full
quieting, then yes 6dB will be noticeable.


--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR

I have a couple of GP-9s and can tell you the gain figures are a bit
inflated and not referenced to anything. A dipole array with optimum
spacing between dipoles is about the most gain for size that I have
encountered in VHF/UHF antennas. For VHF, a four bay dipole array at
20ft in length has 6dBD gain omni and the GP-9 claims 8.5dB(?) from
three 5/8 elements. On UHF, a 16 element dipole array has about 9.8dBD
gain and the GP-9 claims 11.9dB(?) for eight 5/8 elements. Something
looks fishy to me.
Mike


Ken Bessler wrote:
OK, after the thread on PL-259 losses, I figured
my system (ant gain - connector losses - coax loss)

150 mhz total net gain 1.006 DBi
450 mhz total net gain 2.797 DBi
Antenna tip is 32'6" above ground

My proposed system would replace the RG 58 coax pieces
with a single section of Flexi 4XL and the antenna would
be a Comet GP-9. The new figures a

150 mhz total net gain 7.919 DBi
450 mhz total net gain 10.553 DBi
Antenna tip is 47'6" above ground

150 mhz = 6.913 db improvement
450 mhz = 7.756 db improvement
Antenna tip 15 feet higher

Cost - about $250 for the improvement.

Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.


Ken KG0WX

"Ken Bessler" wrote in message
news:lWKjd.75151$%x.68322@okepread04...
OK, after the thread on PL-259 losses, I figured
my system (ant gain - connector losses - coax loss)

150 mhz total net gain 1.006 DBi
450 mhz total net gain 2.797 DBi
Antenna tip is 32'6" above ground

My proposed system would replace the RG 58 coax pieces
with a single section of Flexi 4XL and the antenna would
be a Comet GP-9. The new figures a

150 mhz total net gain 7.919 DBi
450 mhz total net gain 10.553 DBi
Antenna tip is 47'6" above ground

150 mhz = 6.913 db improvement
450 mhz = 7.756 db improvement
Antenna tip 15 feet higher

Cost - about $250 for the improvement.

Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.


Ken KG0WX

The figures speak for themselves. If you are doing any VHF/UHF weak signal
work, regardless of mode, it WILL be noticeable. Depending on the distance
of the sending station or repeater, it can even be noticeable on FM.

Dee D. Flint, N8UZE

"Mike" wrote in message
m...
I have a couple of GP-9s and can tell you the gain figures are a bit
inflated and not referenced to anything. A dipole array with optimum
spacing between dipoles is about the most gain for size that I have
encountered in VHF/UHF antennas. For VHF, a four bay dipole array at 20ft
in length has 6dBD gain omni and the GP-9 claims 8.5dB(?) from three 5/8
elements. On UHF, a 16 element dipole array has about 9.8dBD gain and the
GP-9 claims 11.9dB(?) for eight 5/8 elements. Something looks fishy to me.
Mike


Nothing can distpute your math - something's up.

I've changed plans a bit, though - the Boeing ARC 2 meter
repeater is only 4,000 feet away and I'm worried about
intermod. So, instead of a high gain antenna at 20', I'm going
to go with a moderate gain antenna 10' higher. The idea is
to get good gain with a farther horizon rather than high gain
with a closer horizon.

Plus, it's cheaper, too!

Instead of the GP-9 @ 20', I'm going to add a 10' mast
and go with a GP-3. Installation sould be a lot easier, too.
Now, though, my gain figures are 2.913 db improvement
on VHF and 3.056 db improvement on UHF.

I'm seriously starting to wonder if I should just leave well
enough alone - the MFJ-1729 is performing well. I was
talking to N0IDW on the 145.19 Winfield, KS machine
(a distance of 32 miles) and I could hit the reverse button
and hear him on the input. He, however, could not hear me
on the input.


Ken KG0WX

On Mon, 8 Nov 2004 07:56:46 -0600, "Ken Bessler"
wrote:

OK, after the thread on PL-259 losses, I figured
my system (ant gain - connector losses - coax loss)

150 mhz total net gain 1.006 DBi
450 mhz total net gain 2.797 DBi
Antenna tip is 32'6" above ground

My proposed system would replace the RG 58 coax pieces
with a single section of Flexi 4XL and the antenna would
be a Comet GP-9. The new figures a

150 mhz total net gain 7.919 DBi
450 mhz total net gain 10.553 DBi
Antenna tip is 47'6" above ground

150 mhz = 6.913 db improvement
450 mhz = 7.756 db improvement
Antenna tip 15 feet higher

Cost - about $250 for the improvement.

Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.


Everything is relative.

As Dee said, if you do weak signal work you will notice it.

If you figure investment Vs performance yours is ahead of mine
http://www.rogerhalstead.com/ham_files/tower.htm in both dollars per
watt and hours to install. Took me two years to install, but I do put
it to use. OTOH I've thought of replacing the UHF/VHF arrays with a
single Diamond dual band repeater antenna, EXCEPT for the lightening
problem.
That tower has been taking about 3 hits a year and I have one Diamond
repeater antenna in the shop that looks like a well used exploding
cigar. The top end is pretty frazzled and the matching network in the
base is shorted. Inside it vaporized the top 4 or 5 inches of the end
element.

In my opinion the height is the important element, but I'd not worry
about the extra gain of the antenna. OTOH you *might* receive some
intermod, but you *probably* won't. (note weasel words)


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Ken KG0WX

150 mhz = 6.913 db improvement
450 mhz = 7.756 db improvement
Antenna tip 15 feet higher

Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.


Ken KG0WX

Well, Ken maybe your "OM's" didn't eat their Wheaties. A 6dB improvement means
you have quadrupled your ERP over your existing system. You have also
increased the distance to your radio horizon with the increse in antenna
height.

Why they would say you won't notice an improvement is beyond me. In plane
language here are a few things just a 6dB improvement mean. You can reduce
your radios Tx power by a factor of 4 and have the equivalent ERP, 6dB doubles
your range Tx and Rx (within the limits of your stations LOS - line of sight).
Stations that were noisy will now be full quieting, be it simplex or repeaters
you work.

In even simpler terms, "night and day".

What are you waiting for?

Regards, Hugh KF6HHS
Retired, now life moves at my pace.
please note spam filter

I've changed plans a bit, though - the Boeing ARC 2 meter
repeater is only 4,000 feet away and I'm worried about
intermod. So, instead of a high gain antenna at 20', I'm going
to go with a moderate gain antenna 10' higher. The idea is
to get good gain with a farther horizon rather than high gain
with a closer horizon.

Plus, it's cheaper, too!

Instead of the GP-9 @ 20', I'm going to add a 10' mast
and go with a GP-3. Installation sould be a lot easier, too.
Now, though, my gain figures are 2.913 db improvement
on VHF and 3.056 db improvement on UHF.

I'm seriously starting to wonder if I should just leave well
enough alone - the MFJ-1729 is performing well. I was
talking to N0IDW on the 145.19 Winfield, KS machine
(a distance of 32 miles) and I could hit the reverse button
and hear him on the input. He, however, could not hear me
on the input.


Ken KG0WX


Don't change the antenna but go for height and a good grade of coax. It
won't show up for about 50 feet or so of coax on 2 meters but if going to
100 feet of coax it will on 440.
If your setup is doing what you want it to put the money to something else.
I don't do too much with the repeaters and FM so I was just using some rg-59
(75 ohm coax) to a home made dipole about 20 feet up the tower. It does
what I want it to on FM. Unless it was to add some tower I would not spend
$ 250 for an FM antenna system just to work repeaters.

Actually, there is quite a lot of fun to be had working FM simplex
and repeaters here when the band opens up. One minute you're
rag chewing with the locals on 146.490 simplex & the next thing
you know someone checks into the group from 3 states away!

That's when it's time to switch over to the beam and the Elecraft.

A few years ago I was living on a hill. With a 14 element yagi on
a 35' mast, I could just hear the Tulsa 145.110 machine when the
band started to open. Then it'd open up 100% and I'd talk to south
Texas on 2m FM or 450 miles away on 446.000 simplex.

Neat!

Ken KG0WX


That setup is a big differance than in your first posting. I mentioned I do
not do much FM work on 2 meters . I do work weak signal on 2 meter and 432
mhz ssb. It is not too unusual to work long distances that way. Ham radio
has many things that can be fun. I usually think of the repeaters and FM as
local contacts. I have worked from North Carolina to Canada about twice on
2 meter FM. Using a good antenna and ssb it is common to work out to 200 to
300 miles. The band "opens" a lot more if you have the advantage of about
10 to 20 more db of ssb.

Ralph Mowery wrote:


That setup is a big differance than in your first posting. I mentioned I do
not do much FM work on 2 meters . I do work weak signal on 2 meter and 432
mhz ssb. It is not too unusual to work long distances that way. Ham radio
has many things that can be fun. I usually think of the repeaters and FM as
local contacts. I have worked from North Carolina to Canada about twice on
2 meter FM. Using a good antenna and ssb it is common to work out to 200 to
300 miles. The band "opens" a lot more if you have the advantage of about
10 to 20 more db of ssb.


Good luck following the weak signal VHF/UHF track here. 10 meters is
short for this bunch, except for very few. Less than half dozen appear
to know what EME is.

BTDT