Using a VHF marine radio antenna for Motorola VHF radio??

Any thoughts on using a VHF marine radio antenna on a Motorola VHF radio with a maximum output of 50 whats? We want to install a Motorola radio in a fire boat and another in our quarters using marine radio antennas working on our FD channels in the 154 range/.

Thanks
John

jcityfire said:

Any thoughts on using a VHF marine radio antenna on a Motorola VHF radio with a maximum output of 50 whats? We want to install a Motorola radio in a fire boat and another in our quarters using marine radio antennas working on our FD channels in the 154 range/.



Thanks

John

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I personally would use Motorola antennas especially if it's being used in a mission critical situation like public safety. If you used a third party I can't see it being an issue in terms of transmitting and receiving. Just make sure your antenna is capable of handling 50 wats of power.


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Pro-91, MTS 2000 800MHz, Astro Saber VHF, APX 6000 7/800MHz

jcityfire said:

Any thoughts on using a VHF marine radio antenna on a Motorola VHF radio with a maximum output of 50 whats? We want to install a Motorola radio in a fire boat and another in our quarters using marine radio antennas working on our FD channels in the 154 range/.

Thanks
John

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You didn't say where you are, so I can't tell if salt is an issue. That can greatly affect the potential answer.

Check the specs on the marine antenna. If it has a operating bandwith sufficient to reach your FD frequency on the Tx side, it could be a good choice. But if the bandwidth is really narrow, you probably would get poor SWR meaning that the radio won't transmit very well.

Also, most marine antennas are built for 25 watts which is the marine VHF max power. Again, check the specs before proceeding. If in doubt, I'd suggest looking at a no-ground-plane mobile antenna.

I don't see a good reason to use a marine antenna on a land location when you can get a good base antenna for similar money. But if you already have the antenna and it meets the bandwidth and power suggestions, it could work fine. Just remember that height and coax are critical for land antenna installations. There's tons of coax discussion already here on RR so I don't see the need to fill this thread with that topic.

All great feed back thank you. We are on salt water, our other Motorola UHF and VHF antennas on another boat were installed using motorola antennas that come with the radios and the bottom side of the antenna is made to go on the inside of a vehicle and they don't last long. The radio company changed them out and but a dielectric grease in it then gooped silicone all over it, it still didn't work well. The antennas I have been look at are 50W max input. How does this one look?

Centennial 5101 Specifications
Band: VHF Marine Band
Antenna Gain: 6dB
Max. Input Power: 50 watts
SWR: nominally 1.5:1 at 156.8 MHz
Bandwidth: 5 MHz within 2.0:1 VSWR
Ferrule: Chrome-plated brass
Coax Supplied: 15 ft of RG-58
Connector Supplied: PL-259, not installed
Color/finish: White
Polarity: Vertical
Impedance: 50 Ohms
DC Ground: Special – DC Grounded, but reads “open” on ohm meter

jcityfire said:

All great feed back thank you. We are on salt water, our other Motorola UHF and VHF antennas on another boat were installed using motorola antennas that come with the radios and the bottom side of the antenna is made to go on the inside of a vehicle and they don't last long. The radio company changed them out and but a dielectric grease in it then gooped silicone all over it, it still didn't work well. The antennas I have been look at are 50W max input. How does this one look?

Centennial 5101 Specifications
Band: VHF Marine Band
Antenna Gain: 6dB
Max. Input Power: 50 watts
SWR: nominally 1.5:1 at 156.8 MHz
Bandwidth: 5 MHz within 2.0:1 VSWR
Ferrule: Chrome-plated brass
Coax Supplied: 15 ft of RG-58
Connector Supplied: PL-259, not installed
Color/finish: White
Polarity: Vertical
Impedance: 50 Ohms
DC Ground: Special – DC Grounded, but reads “open” on ohm meter

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I don't find anything negative about that antenna for your application except to note that you'll have to mount it wisely on a fire boat so that it does not interfere with fire fighting and rescue operations. Follow Shakespeare's instructions on installation and protection of the metal parts from salt water corrosion.

One final point, double check the SWR after installation. If it's too far off, have a competent tech take a look at it.

Steve is right on.
There is no requirement or need to stick with Motorola branded antennas. Motorola doesn't make their own antennas anyway, they're relabeled from other brands. In all the radios I've installed I've never seen anything from Motorola that requires using their antennas.

Marine VHF antennas can vary greatly in quality. Some of the low end models are simply a stripped back piece of coax stuffed inside a fiberglass tube. They'll work, but they really are not worth the price and I wouldn't trust one in your application.
The better marine VHF antennas have actual metal rods inside and will stand up to a lot more abuse. They'll be more expensive, but they'll last you a lot longer.

After a few years in the USCG, I can tell you that most of our marine VHF stuff was commercial off the shelf, including the antennas. They were the high quality antennas, but they did just fine, and that was years of being beat hard on the Bering sea. Never saw one fail.

The other benefit to specific marine antennas is that they use the standard 1"x14 mounts. While I love NMO's, I'd be reluctant to use on in a marine environment, especially if it was mounted in a location that didn't provide easy access for frequent maintenance, like up on the mast head.

You'd be best to go with a known company and order the specific antenna you need, not just a generic marine VHF antenna. You can get suitable antennas for VHF, UHF and 700/800MHz, WiFi, cellular, etc. They use the standard 1 inch x 14 mounts common to the marine antennas and are specifically designed for use in marine (even salt water) environment.

Ideally, you'd use one of these, ordered the specific model for your frequency, they have versions that cover from 144MHz all the way up to 174MHz. Rated for 250 watts:
MS150U-XXX - COMTELCO Communication Products

The marine VHF band is between 156 and 160.2 MHz. That's higher than your 154 MHz requirement, so the SWR will not be a good match and don't expect awesome range.

It's probably not far enough off to damage your transmitter but I would always recommend that you use an antenna that is made for the frequencies you're using. "Close enough" really isn't.

We run a marine antenna on our VHF radio on our boat. Most of the time we are on the marine channels so its not a big deal, but have used our local VHF channels for incidents with no issues. We do have a few 151.xxx channels and just run low power on them. I'm sure when you get down that low they aren't great but its normally used to talk to the dock coming in.

ElroyJetson said:

The marine VHF band is between 156 and 160.2 MHz. That's higher than your 154 MHz requirement, so the SWR will not be a good match and don't expect awesome range.

It's probably not far enough off to damage your transmitter but I would always recommend that you use an antenna that is made for the frequencies you're using. "Close enough" really isn't.

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I am pretty sure the OP is running marine on a separate radio with a matching antenna. That's the norm for fire and LE boats. Marine radios are required to constantly monitor 16 in addition to whatever channel they're operating on. LMR radios generally don't do that, and the normal scan functions that we're all used to don't meet that requirement.

Since the antenna he mentioned has a 5 MHz bandwidth centered on 156, it should work just fine on his 154 fire frequencies.

Marine Rx/Tx frequencies are all 156.xxx or 157.xxx. AIS is 161/162, but it's usually a separate piece of equipment from the marine transceiver with it's own antenna. Marine radios do receive the NOAA weather channels, but that is not dependent on the antenna's transmit characteristics.

Thanks for all the great feed back and ideas. I this were going to go with a good quality marine radio for the boat and a base antenna for our quarters. Trying to keep within our budget for this project, I found the antenna I linked below. Any thoughts on it? Good, bad or indifferent.
Thanks

http://www.theantennafarm.com/catalog/browning-br-6050-3570.html

Browning and Tram are made in China, at least their mobile antennas are.
They bought the rights to the brand names that used to stand for something back in the 70's, unfortunately.

I've seen some of their mobile antennas at trade shows. They look halfway decent, but not up to the quality of the name brand stuff.

I've never owned one, looking at them and seeing only a very minor cost differential made me stick with the known good stuff. I'm sure there are those that are happy with the brand, but then again, there are those that are happy with the $35 Chinese dual band radios, too.

For life safety use? I'd be reluctant to use a Tram or Browning antenna when you can spend slightly more and get a known good brand.

Thank you for the input MMcKenna, I lke the one you recommended but it's out of our budget at $273.00. Is there a less expensive one? Thanks

jcityfire said:

Thank you for the input MMcKenna, I lke the one you recommended but it's out of our budget at $273.00. Is there a less expensive one? Thanks

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I may be able to get a better price on the Comtelco, and can drop ship. PM me.

More like $160.