VHF/UHF Antennas for GMRS

[DownEastNC]

Many GMRS radios come with VHF receive only and of course the standard RX/TX GMRS channels. My KG-935G can receive VHF 136-174.995 MHz. My question is, does a dual band antenna buy me anything for receiving VHF frequencies or is it better to just stick with a UHF GMRS specific antenna?

I've been looking at the Comet FC-54NMO;

VHF/UHF Dual Band Antenna1.5:1 or less
SWR:153-157/460-470MHz
Gain: 2.15/5.0dBi
Max Power: 50 watts
Length: 36 inches
Connector: NMO Fold-over hinge included

The VHF portion of the antenna doesn't accommodate the full spread of frequencies that my radio does but it's in the ballpark. Thoughts?

[mbrun]

All my GMRS radios receive VHF. I'm simply asking if a VHF/UHF antenna helps on the VHF receiving side without compromising GMRS communications.

Good Day DownEastNC.

An antenna that has been optimized for GMRS frequencies will equally well for both transmit and receive. It will receive almost all other frequencies too, but it will not perform as well as an antenna that has been optimized for the other frequency(s) of concern.

The same can be said about a dual-band amateur radio antenna. Said antenna will perform best on the frequencies for which it has been designed/optimized (2m & 70cm). A few designs might have characteristics that make it acceptable for use also on GMRS but they will have lesser performance than a similar design optimized for GMRS.

So, the bottom line is YES. If you are using an antenna optimized for amateur frequencies you are indeed compromising GMRS communications. Whether that compromise is material to you is totally up to you.

I own both GMRS and amateur radios and antenna. Where weak stations are concerned, the GMRS multi-band radio used with the GMRS antenna receives GMRS signals more strongly than its amateur radio antenna and receiver. The reverse is also true. If I switch the GMRS radio to receive VHF frequencies, the amateur radio receives the signals more strongly. In both cases this is due to what the antenna is are optimized for.


Michael
WRHS965
KE8PLM

[MichaelLAX]

In another thread, I seemed to have engendered some argumentative replies to my suggestion that having a dual-band antenna matters when attempting to listen to marginal VHF stations.

I will say that MY preference is to go with a good dual-band antenna for a dual band radio!

[n9zb]

I have a Comet GP-3 that was my base antenna for ham radio 2m/70cm bands.

It does ok on GMRS frequencies, so guess what I'm using it for now?

[wayoverthere]

1 hour ago, DownEastNC said:

Many GMRS radios come with VHF receive only and of course the standard RX/TX GMRS channels. My KG-935G can receive VHF 136-174.995 MHz. My question is, does a dual band antenna buy me anything for receiving VHF frequencies or is it better to just stick with a UHF GMRS specific antenna?

I've been looking at the Comet FC-54NMO;

VHF/UHF Dual Band Antenna1.5:1 or less
SWR:153-157/460-470MHz
Gain: 2.15/5.0dBi
Max Power: 50 watts
Length: 36 inches
Connector: NMO Fold-over hinge included

The VHF portion of the antenna doesn't accommodate the full spread of frequencies that my radio does but it's in the ballpark. Thoughts?

Given that it's got some gain in vhf, it will likely help, although not quite as much if it were focused in the range you want (gain helps both transmit and receive).

On the other hand, if it were focused lower, the UHF side would likely be focused lower as well, which we don't want....where its tuned is more critical for transmit, and that 460-470 is the range you want for gmrs.

Some Dual band antennas for the ham 2m/70cm bands can work well, and others, less so, given they're generally tuned for lower frequencies in both bands.

[WyoJoe]

2 hours ago, DownEastNC said:

Many GMRS radios come with VHF receive only and of course the standard RX/TX GMRS channels. My KG-935G can receive VHF 136-174.995 MHz. My question is, does a dual band antenna buy me anything for receiving VHF frequencies or is it better to just stick with a UHF GMRS specific antenna?

I've been looking at the Comet FC-54NMO;

VHF/UHF Dual Band Antenna1.5:1 or less
SWR:153-157/460-470MHz
Gain: 2.15/5.0dBi
Max Power: 50 watts
Length: 36 inches
Connector: NMO Fold-over hinge included

The VHF portion of the antenna doesn't accommodate the full spread of frequencies that my radio does but it's in the ballpark. Thoughts?

If the specs are correct, that looks to be an excellent antenna for GMRS. For VHF reception, having an SWR below 1.5 isn't a necessity. I suspect it will reasonably tune a much wider spectrum that what's stated. If you were wanting to transmit in the VHF range, however, you might want something different, depending on the part of the spectrum you wanted to transmit on.

[DownEastNC]

I have found a base station version of this antenna. So, in my application of a mobile and a base station, and the radios that I will be using which both have RX VHF frequencies then it sounds like I won't be hurting myself by going this route. I don't believe that I will ever be transmitting VHF on these sticks. It's mostly for listening in on some emergency services, Marine band, and any other entertaining thing I can find in that frequency spectrum. Otherwise I'll be using GMRS more and more as time goes on and as I can get more folks interested in the medium. Currently I live in GMRS no man's land and it's rather quiet out here.

Comet GP-6NC 153-157/460-470MHz Base/Repeater Antenna

VHF/UHF Dual Band Antenna 1.5:1 or less

SWR: 153-157/460-470MHz

Gain: 6.5/9.0dBi

Max power: 200 watts

Length: 10 ft 2 inches

Weight: 3 lb 8 oz

Connector: N-female

Construction: Two-piece white fiberglass

Max wind speed: 112MPH

[DownEastNC]

54 minutes ago, n9zb said:

I have a Comet GP-3 that was my base antenna for ham radio 2m/70cm bands.

It does ok on GMRS frequencies, so guess what I'm using it for now?

Your link takes me to Nowheresville. It says I'm forbidden, which is pretty much the story of my whole life

[n9zb]

1 hour ago, DownEastNC said:

Your link takes me to Nowheresville. It says I'm forbidden, which is pretty much the story of my whole life

Hm. Wasn't supposed to be linked anywhere, just show the pic.....

[DownEastNC]

8 minutes ago, n9zb said:

Hm. Wasn't supposed to be linked anywhere, just show the pic.....

I get a 403 Error from Google with the 'Forbidden' warning.

[wayoverthere]

1 hour ago, DownEastNC said:

Your link takes me to Nowheresville. It says I'm forbidden, which is pretty much the story of my whole life

i had less luck with the gp1 (2.4 on 462.xxx, and 3.0 on 467.xxx) that is my 2m/70cm.  This is why i chose to keep the dual band ham radio at home (doing 2m/70cm together) and run gmrs on a separate midland 5/8 wave, rather than combining 70cm and gmrs (dual cert vertex), with a 2m monoband radio.  the vertex went to the truck instead.

and this one should work (for the gp3 photo):

[OldRadioGuy]

I depends on the matching network (if any) on your GMRS antenna.  If it has a matching network and it's a high pass type design it will attenuate the lower freq signal.  I think many GMRS antennas do not require a matching network so not super likely that there is a high pass network in the bargain. 

I have tested a few dual band 2M/70cm antennas on my GMRS radio and SWR is just fine.  Remember 465 MHz is only 8% higher than 430 MHz.  That's not a big deal.

Vince

[wroe929]

On 10/10/2021 at 12:40 PM, DownEastNC said:

does a dual band antenna buy me anything for receiving VHF frequencies or is it better to just stick with a UHF GMRS specific antenna?

If you're just interested in receive of VHF why spend any money at all?  I'd cut a length of #26 AWG wire (or whatever you have on hand) about 19 inches long and strip the last inch...wrap that last inch of stripped wire around the base (ground side contact) of your HT antenna, screw it down and let it hang.  It'll receive just fine.  You'd be wasting your money buying another antenna in my opinion.  ALSO....IMHO, one shouldn't pay a whole lot of attention to "Gain" claims of antenna manufacturers.

 

[DownEastNC]

1 hour ago, wroe929 said:

If you're just interested in receive of VHF why spend any money at all?  I'd cut a length of #26 AWG wire (or whatever you have on hand) about 19 inches long and strip the last inch...wrap that last inch of stripped wire around the base (ground side contact) of your HT antenna, screw it down and let it hang.  It'll receive just fine.  You'd be wasting your money buying another antenna in my opinion.  ALSO....IMHO, one shouldn't pay a whole lot of attention to "Gain" claims of antenna manufacturers.

 

All my GMRS radios receive VHF. I'm simply asking if a VHF/UHF antenna helps on the VHF receiving side without compromising GMRS communications.

[MichaelLAX]

I have the Comet CX-333 Tri-Band amateur radio antenna in use with my Anytone AT-779UV GMRS radio.  I do not have a SWR meter.

I am able to hit GMRS repeaters easily that are available to me in every direction and it works for 2 meters and MURS on VHF as well.

[WROA675]

11 minutes ago, MichaelLAX said:

Comet CX-333 Tri-Band amateur radio antenna

Considering this for my next antenna (geesh, just got the Larsen's set-up ) as it seems it would be a easy swap and give me better coverage. Quick question...It's already tuned for GMRS correct (no trimming necessary)?

[MichaelLAX]

4 minutes ago, Papatree said:

Considering this for my next antenna (geesh, just got the Larsen's set-up ) as it seems it would be a easy swap and give me better coverage. Quick question...It's already tuned for GMRS correct (no trimming necessary)?

NO: it is tuned for 430-450 Amateur Radio 70 cm band.  Bring your SWR meter over and we can measure it on GMRS.

[DownEastNC]

1 hour ago, Papatree said:

Considering this for my next antenna (geesh, just got the Larsen's set-up ) as it seems it would be a easy swap and give me better coverage. Quick question...It's already tuned for GMRS correct (no trimming necessary)?

There's Comet GP-6NC 153-157/460-470MHz Base/Repeater Antenna tuned for GMRS

It's not in stock but you can see the details; https://www.gigaparts.com/comet-gp-6nc-153-157-460-470mhz-base-repeater-antenna.html

[WROA675]

24 minutes ago, DownEastNC said:

There's Comet GP-6NC 153-157/460-470MHz Base/Repeater Antenna tuned for GMRS

Thanks for the tip. Both ends of my coax are PL 259 male connector and the GP-6NC has a N-female. So would the adapter I need be a PL259 female to N-male?

[wayoverthere]

4 minutes ago, Papatree said:

Thanks for the tip. Both ends of my coax are PL 259 male connector and the GP-6NC has a N-female. So would the adapter I need be a PL259 female to N-male?

That would work to make the connection; on a side note, the female side of pl259 is the so239 (pl=plug, so=socket)

However, if the cable run permits, I'd be tempted to run a a couple to a few ft of cable with N connectors on both ends if it let me get the changeover point inside the attic. N connectors are better protected from the weather than the uhf (pl259/so239) connectors.

[WROA675]

3 minutes ago, wayoverthere said:

That would work to make the connection; on a side note, the female side of pl259 is the so239 (pl=plug, so=socket)

Awesome thanks for the info. Even with a few added feet the changeover point would still be outside, however, it seems that the configuration would still be preferable.  I could tape up the changeover point really good (probably better than I could at the connection point at the antenna) and have the N connecter run straight into the Comet. What do you think?

[MichaelLAX]

50 minutes ago, DownEastNC said:

There's Comet GP-6NC 153-157/460-470MHz Base/Repeater Antenna tuned for GMRS

Looks like it will work for MURS, too! 

The Mavens on this Forum have given me permission to do GMRS/MURS cross band, so I can transmit to you MURS and you can transmit to me GMRS!

[wayoverthere]

3 minutes ago, Papatree said:

Awesome thanks for the info. Even with a few added feet the changeover point would still be outside, however, it seems that the configuration would still be preferable.  I could tape up the changeover point really good (probably better than I could at the connection point at the antenna) and have the N connecter run straight into the Comet. What do you think?

I'd have to look for the specific procduct name, but I know 3m (and others) make a tape aimed at this kind of sealing. If you can do it better outside the connection point, I still would. DX Engineering even has kits, and a how-to document. https://www.dxengineering.com/search/part-type/weatherproofing-kits/product-line/dx-engineering-coaxial-connection-weatherproofing-kits

https://static.dxengineering.com/pdf/weatherproofingcoax-techtip.pdf

[WROA675]

26 minutes ago, MichaelLAX said:

The Mavens on this Forum have given me permission to do GMRS/MURS cross band, so I can transmit to you MURS and you can transmit to me GMRS!

I'm really leaning towards getting this one, I sent Bob a email to see if he has one. My gmrs-mind justifies this swap by saying I can still use the Larsen as a backup for my mobile (camping, or otherwise in those far off, hard to reach spots) 

My rational-mind, however, needs to double check my hoa regs to unsure I'm not going to run into any friction. The Larsen blends in well and inconspicuous (I didn't ask or check with hoa), but the Comet is sure to draw some attention. 

[DownEastNC]

I just wanted to post a follow-up. I decided to go with a straight GMRS base station antenna instead of the UHF/VHF. I purchased a Comet CA-712EFC. IMO it's a pretty nice antenna as far as construction and the hardware included. Until I can perform a permanent installation with some additional height I have it attached to a 16 foot piece of 1-1/4" schedule 40 steel pipe. Height to antenna tip is about 25'. I used 75' of LMR-400 Ultra Flex and routed it into the RV and into a SWR meter. On the other side of the meter is my handheld KG-935G with a SMA female to PL-259. I had a jaw dropping 1.06 SWR on Channel 20 at 4 watts plus some change. I easily hit a repeater 29 miles away and had a nice conversation with a gentleman who gladly gave me a radio check. He said I was coming in strong. I'm waiting for my lightening arrester to arrive and I'll do another SWR check after that is installed. Sometime later in the day I'll be plugging up the KG-XS20G and see what 20 watts does for me. Overall I'm pleased with the antenna and its performance.

[n4gix]

I've used my Comet CA-712EFC for the past six years and have been extremely pleased with it. I highly recommend using some 1.5" heat shrink on the connector that fastens the top/bottom sections of the antenna together. That will prevent any water ingress.