Business Band Antennas?

[PartsMan]

I have some old Larsen UHF antennas at work. Any chance they would work for GMRS.

Maybe need tuned?

One of the old Motorola radios said 470mgz.

I am wanting to use one for an external on my GM-30 handy talk.

 

[PACNWComms]

You could possibly use some of those. Many Larson 5/8 wave NMO antennas  were for 450-470 MHz. I would definitely check with a meter and tune as necessary. I have used many commercial UHF antennas for GMRS use myself. If they are 450-470 MHz antennas, then they work great for GMRS with 462-467 MHz, right in the middle "sweet spot" for the antennas. However, there are some that are for lower UHF frequencies, 403-450 MHz, which will look a lot like the higher frequency versions, those will show higher SWR with a meter, and should not be used for GMRS. With the antenna being the most important part of using a radio, you do not want to fry a radio with a mistuned or different band antenna, it is not worth it to save a few dollars. But, that picture looks like they could be 450-470 MHz and great for GMRS.

[BoxCar]

The 403-450 MHz antennas can be trimmed for GMRS but it would be very easy to trim a bit too much ruining the antenna.

[PartsMan]

I looked at the old Motorola SM50 radios that they were used with. There model numbers indicate 450-470.

I don't have a SWR meter to check with.

[AdmiralCochrane]

nanoNVA is better for trimming antennas anyway 

[PACNWComms]

7 hours ago, PartsMan said:

There model numbers indicate 450-470.

If it were my antennas and radio, I would be fine with using them for GMRS. The GMRS band is right there in the middle of 450-470 MHz, so it would not be a big deal for me to go ahead and use them without a meter. My only concern would be if I could not hear/receive anything on the radio, as that would point toward broken connector, center pin or spring on the antenna to base connection, or some other broken component. While others may state that you must never use a radio and antenna combination without checking SWR, knowing what that antenna was made for, it is probably fine to go ahead and use them for GMRS, at your own risk of course. Those antennas and mounts may look pretty cool on an older car, for that retro look for sure. 

[DONE]

Larsen typically would print a model number on the bottom of their antenna's.  Unscrew the NMO base from the mount and see if the number is there.  Then look up the number and see what frequency band it is.  Don't assume they they are right,  seen the wrong antenna's used with a radio many times

 

[PartsMan]

I tried it for the last two days. Receiving is much better than the rubber duck in the truck.

I transmitted and nothing exploded or caught fire. 

I look forward to doing a range comparison.

[gortex2]

Asstated GMRS is in the middle of the business band. Most any UHF 450-470 antenna will perform fine. 

[PACNWComms]

On 1/26/2022 at 1:40 PM, PartsMan said:

I tried it for the last two days. Receiving is much better than the rubber duck in the truck.

Glad that is working out for you.

For other possibilities:

For most of my use cases with GMRS, I am running some sort of Motorola radio. So I end up using lip mounts with a NMO (New Motorola) base, and a Laird 1/4 wave 6" long antenna. they are fairly discrete, yet still get out well when mobile. 

Shown in my picture is a magnet mount Laird GB8UM with mini-UHF connector (for mobile Motorola radios), and a Laird QW450 (to 470MHz) antenna that works very well with GMRS in the 462-467 MHz spectrum.