Can a HAM radio antenna be used for GMRS?

[WSFZ339]

A VHF/UHF 144/430 antenna that is used for HAM radio, can that be used for GMRS too?

I'm talking about a Comet gp9 or gp3, etc. A tower/ roof mount antenna. One that can switch back-and-forth to either a HAM or GMRS radio.

[Socalgmrs]

I run a gmrs comet712efc works great in gmrs and a duel band comet 6nc and a duel band comet 9nc.  Both work just fine in gmrs 

[WSFZ339]

52 minutes ago, Socalgmrs said:

I run a gmrs comet712efc works great in gmrs and a duel band comet 6nc and a duel band comet 9nc.  Both work just fine in gmrs 

You have all those antennas for GMRS? You use them for HAM too?

[WRTC928]

I do it. You have to be sure to check SWR all the way up and down the bands because some antennas aren't tuned well enough to the 462-467 MHz range. I've had good results with the Comet SBB-1 and SBB-2 and the Nagoya UT-72 and NMO-72 antennas. In terms of getting good SWRs all the way up to 467, the UT-72 gave me the best results. Some folks say the Nagoya 72s are trash, but I've gotten good performance from them. I'm not trying to reach ridiculous distances, so YMMV.

[WRYZ926]

I have a Comet GP-9 and the SWR is 1.8 on 467 MHz and 1.5 on 462 MHz. That being said, I still run a Comet CA-712EFC for my GMRS radio so that I can run my GMRS and dual band radios at the same time.

[73blazer]

I have a Diamond Supergainer 7900 2m/70cm in my mobile setup when used in it's design range SWR is 1.2-1.3:1 . WHen used on 462/467 SWR is 1.4:1 still very acceptable for me.

But the Supergainer 7500  2m/70cm does much better even though is slightly less spec'd gain in it's design bands. SWR of 1.2:1 on all design bands as well as on 462/467 with a KG-UV980P mobile radio (same as KG-1000G just not locked to GMRS) .

Both tested using an NMO tri-mag base on the roof of my crew cab dodge.

[Lscott]

38 minutes ago, 73blazer said:

But the Supergainer 7500  2m/70cm does much better even though is slightly less spec'd gain in it's design bands. SWR of 1.2:1 on all design bands as well as on 462/467 with a KG-UV980P mobile radio

What did you use to test the SWR?

I've done some testing myself using a Rigexpert AA-1000 and didn't get great results with the 7500. The comet CA-2xSR did reasonably well. My old Comet dual band CA-2x4MB is the best one I've had, but it's not manufactured anymore.

These antennas are sensitive to the type and location of the mount being used. Particularly the CA-2xSR.

I currently have the CA-2x4MB on my Mazda. The fold-over spring is weak so I have the antenna permanently taped so it doesn't flip over while driving. I have a spare brand new one still in the green plastic packaging. The antenna is about 60 inches tall so I have to be EXTRA careful where I drive.

https://forums.mygmrs.com/gallery/image/471-mobile-mount-with-antenna-rear-view/?context=new

https://forums.mygmrs.com/gallery/image/473-close-up-of-mobile-mount/

And this is when I had it on the old Jeep.

https://forums.mygmrs.com/gallery/image/259-ca-2x4mb-jeepjpg/?context=new

 

Antenna Scan Results (CA-2x4MB VHF Jeep).pdf Antenna Scan Results (CA-2x4MB UHF Jeep).pdf Antenna Scan Results (CA-2x4MB MURS Jeep).pdf Antenna Scan Results (CA-2x4MB FRS_GMRS Jeep).pdf CA-2x4SR VHF TRI MAG MNT.pdf CA-2x4SR UHF TRI MAG MNT.pdf SG7500A VHF Scan GND Radials.pdf SG7500A UHF Scan GND Radials.pdf

[WSAM454]

15 hours ago, WSFZ339 said:

A VHF/UHF 144/430 antenna that is used for HAM radio, can that be used for GMRS too?

I'm talking about a Comet gp9 or gp3, etc. A tower/ roof mount antenna. One that can switch back-and-forth to either a HAM or GMRS radio.

Most of the antennas mentioned are mobile; the OP specifically asked about tower/roof mount antennas. 

Most of those for the ham bands will have a higher SWR on the GMRS band.   Just how high, and whether your radio will still operate  safely is not certain.

The only antenna I am aware of that is designed for use on all 3 bands is a mobile one, the Comet CA-2x4SR. 

My GP-3 has an SWR about 4:1  on the repeater freqs, with reduced power output.   You would have to decide if that is OK.

[WRYZ926]

The Comet GP9 is a tall antenna and not everyone wants or can have an antenna that tall. Several of us in my local club use the GP9 and we tested all of them on the GMRS channels.

The SWR on 467 MHz averages around 1.7 to 2.1 and the SWR on 462 MHz averages around 1.3 to 1.5 on all of the GP9 antennas we tested. I'll have to see if anyone local has the Comet GP6 to test.

[tweiss3]

Short answer is yes. Longer answer is depends on each antenna's sweep and what you are comfortable with. I specifically choose antennas that meet my intended needs.

[73blazer]

28 minutes ago, Lscott said:

What did you use to test the SWR?

I just have a Surecom SW102, it's not the most accurate for sure, but it gives the general idea. On my all fiberglass K5 blazer the same 7500 antenna and radio only gives 1.8:1 because I can't get a very good ground plane on the vehicle.

[RIPPER238]

I purchased a Comet CA-2X4SR & SBB-1NMO (Shorter option) for my handheld 2M 70CM/GMRS use on the roof of my truck even though they aren't specifically for GMRS. Installing a new mount, but have herd good things about both antennas as more versatile option for 2M 70CM/GMRS. 

I will note I also have a dedicated GMRS radio in my truck with a dedicated GMRS antenna for heavier use. 

[WRYZ926]

I have a Comet 2x4SR and SBB1. Both are 1.8 or below for 2m, 70cm, and GMRS. I still run and operate GMRS only antenna on my Ford Escape since I like to use my dual band and GMRS radios at the same time. The same goes for my base station. I run the GP9 for dual band and the CA712EFC for GMRS.

The 2x4SR is a good multi band mobile antenna and works well for 2m, 70cm, MURS, GMRS and VHF public safety frequencies.

[AdmiralCochrane]

My home made 70/65cm Slim Jim is below 1.6 swr about half way across both bands according to my nanoNVA.  I really didn't expect it to be that good across that much.  I have my GMRS radio attached to it.