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Reviews Categories | Antennas: VHF/UHF+ Omnidirectional: verticals, mobile, etc | Comet GP-9 dual band base antenna Help

Reviews Summary for Comet GP-9 dual band base antenna
Comet GP-9 dual band base antenna Reviews: 46 Average rating: 4.3/5 MSRP: $200 about
Description: Ultra High Gain Dual Bander for 146 & 446Mhz
Product is in production.
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You can write your own review of the Comet GP-9 dual band base antenna.

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W4ONC Rating: 4/5 Mar 7, 2013 18:21 Send this review to a friend
Set Screws  Time owned: 0 to 3 months
Putting the GP-9 together was easy until I noticed that the very small set screws were missing. These small set screws hold the elements together. I called the 1-800 number to find out that I had to call another number in California (1-909-393-6133) for the screws. They came within 2 days at no cost. I am pleased with their service. So far it seems to be working fine.
K3DAV Rating: 4/5 May 30, 2012 13:46 Send this review to a friend
Best 2M Vertical Ever  Time owned: 0 to 3 months
I replaced an old Comet GP-15 with a Dominator 6M antenna, and a new GP-9. At first look, the GP-9 seems like a stupid way to build this antenna. The 3 sections are open ended with a wire sticking out and the owner must connect the wires before locking the fiberglass poles together with compression connections. This is a poor design and makes no sense.

But I pulled out the wires from each section to inspect them for cold solder joints that have been known to exist in the GP-9. I was lucky enough to find all good connections on mine.

After installing the GP-9, I found a flat 1.1 SWR from 144 through 147MHz. Then a slight rise in SWR to a 1.4 at 148MHz. On UHF, the SWR is constantly up and down across the entire 30MHz of 440. But the "downs" are flat and the "up's" never peak above 1.5. So I can not complain about the great SWR at all, and the great SWR assures that all connections inside the antenna are good ones.

As for performance, I expected bigger improvements than I got. On VHF, the local signals are about the same as with the old GP-15, and distant signals show a 1 to a rare 2 "S" unit increase.

On UHF I noticed very little difference if any when compared to my old GP-15 only half the size and less gain. So in my opinion the GP-9 is a good 2 meter antenna. Probably the best 2 meter vertical on the market. But for UHF, a home-brew wire dipole will do as good. The gain factor for UHF is greatly exaggerated.

I have a great detailed article about the GP-9 and my performence review of the GP-9 and other antennas on my website at..

Over all, the GP-9 is a great 2 meter antenna, but Comet could have designed the construction much better.
VA7DH Rating: 5/5 Feb 12, 2012 21:07 Send this review to a friend
Excellent performer  Time owned: 6 to 12 months
I read of good things about this antenna and have recommended it to a couple of other people. All of us work a weekly simplex net and one lady only had a hand held 2m radio. Once she got onto the GP-9 she sounded like she was on a mobile with 10 times the power. She now has a mobile on simplex net and everyone hears her clearly. It's an impressive antenna. We live in a wet area too and no problems with either antenna so far and they have been up several months for one and over a year for the other. We also live in an area with lots of mountains and hills so hard finding a good line of site heading. Nevertheless, the GP-9 performs outstandingly, probably better than a Yagi with a rotor for this application.
W8STU Rating: 5/5 Mar 28, 2011 11:30 Send this review to a friend
GREAT ANTENNA  Time owned: more than 12 months

I have had three of these great antennas. I had one on my vacation home, one on my now EX-wife's house, (which is still up going to waste.), and I have one now at my current QTH. They work great. I can get into distant repeaters which are at least 60 miles from me full quieting. They last a long time. The one I have now has been up at three different locations for the past 10 years. I have had no problems with it. This last one, when I was putting it together to put up the whole insides slid out. I had to carefully slide it back together. Naturally I was worried. I got it back together and everything was still great. No problems. That shows how well they are put together and how forgiving they are. I would highly recommend this antenna. When this one does finally bites the dust I will buy another one. Thanks in advance. 73, Stu de W8STU
IZ2QDD Rating: 5/5 Jan 15, 2011 00:21 Send this review to a friend
The greatest antenna!  Time owned: more than 12 months
Compared with the other antennas is truly superior. In comparison to the Diamond X-510N else is not history, it is possible to go over 147 MHz without any problem and may very well receive the Air Band. After two years I can say that works well and allows me to also cover distances over 200Km.No problem for the SSB band.
K9VUJ Rating: 5/5 Jun 3, 2010 16:49 Send this review to a friend
12 years  Time owned: more than 12 months
I decided to replace the very old RG213 with LMR400 so I removed the antenna after 12 years on top of my W51 tower. I completely disassembled the antenna for inspection. I found nothing that needed repair. It was dry inside the radome and all connections looked as new. The fiberglass was is excellent shape. I did have some problem getting the tube unscrewed to expose the N-connector, but after applying some juice it came free. I would recommend using anti-seize grease to those threads. It's now back up for another 12.

KA7EII Rating: 5/5 Mar 7, 2010 06:16 Send this review to a friend
Great Antenna  Time owned: more than 12 months
My Comet GP9 has been in use for over 15 years and has always performed perfectly. Currently it is up 30 feet and is being fed with about 100 feet of 9913. Run 50 watts on 2m and 20 watts on 70cm with a Yaesu FT-100. I can work simplex (other base and mobile stations) up to 50 miles away and am able to work some repeaters over 100 miles away.
N2SLO Rating: 5/5 Mar 2, 2010 16:44 Send this review to a friend
Still Kicking 8 Years Later  Time owned: more than 12 months
I did an initial review back in June 2002. Since that time I have added an 8 Element Quad, and mounted the beam in the GP 9's place. With over 400+ watts, and the beam my signal is at least 4-5S units higher for distant stations. The GP 9 is now mounted on our house vent pipe, for repeater use and hears well. No issues, no rust, very good condition. I use the 9913 which is prone for water leaks. I must have used good "stuff" to seal, since no SWR issues. 1.1 145-147....
KG4OHH Rating: 4/5 Mar 2, 2010 16:16 Send this review to a friend
Fixing the GP9  Time owned: more than 12 months
After having no problems for over 4 years with this antenna in service, we moved from Fl to WA about 6 months ago, and now the antenna (GP9) had a SWR of 1:1:1 now has SWR of 3++

Rain water in the Antenna:
After looking over the antenna (GP9) again, I found 2 tiny Allan grub screws (hex), i pulled them out, slid the ground plane out of the way I was able to pull the entire so239 and connecting element the hole thing, and slid it out of the tube via the bottom, on the co-lininer elements they have used sponges used and insulators to stop the elements from bouncing around inside the tube of the antenna, well these where soaking wet!!!

according to the MFJ 269, the resonant Frq is now 165.500 with SWR of 1.3:1 anywhere above or below this (in Vhf) SWR reads 3++, one thing i did notice is that when i wiggled the base of the antenna (so239 end) the SWR was jumping around 2 to 3 to 2 in the 2 meter band

I have now de coupled the bottom end of the antenna (see pic); and have it in my hand, I also have sprayed it with CrC Switch cleaner, to get out any unwanted water residue I have used a DVM to check for connections as follows:

Center to Center before the blocking cap, good short

outer to outer before the 2nd blocking cap good short

Center to outer no short before or after cap

both caps are ceramic types labeled as:

(C1) 10J, 1kv and reads on DVM set to cap mode 0.215 Nf

(C2) 1.5c, 1Kv and reads on DVM set to cap mode 7.61 Nf and then meter reads O.F (over flow)?

I am using the radio shack DVM model/cat number: 22-811

I am going to re heat up the solder joints as i can see some type of powder residue and then clean it up with a fine file

dose anyone, at this point, recommends doing anything else while i got the antenna in bitz ?

thank you for all who have helped
and will post an up date if this works out
N1MJF Rating: 5/5 Feb 22, 2010 12:26 Send this review to a friend
Couldn't be better  Time owned: 6 to 12 months
My only complaint is that any frequency that I tune in I can hear 2 or sometimes 3 repeaters. I have it mounted 20' above ground and I have no issue getting into a repeater that is 50 miles away on 5 watts daily.

The receive gain on this antenna is almost too much for an omnidirectional antenna if you plan to use it for local repeaters.

As for power handling, it handles my 100w FM amplifier just fine with a dead flat 1:1 SWR on 2 meter simplex. I have not ran anymore then 25 watts on 440MHz.
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