GMRS Amplification

[shevo7385]

I am extremely new to the world of gmrs...less than a month new. I was wondering if there are relatively inexpensive amplifiers you can put somewhere in between the base station and the antenna which will boost power in terms of wattage. Any help to products or information would be super helpful. I know there is a transmission limit as per regulation but are there products out there?

[marcspaz]

Any UHF amplifier that covers up to 470 MHz should be fine.  However, there are some really big warnings I have about using an amplifier.

 

First, on the 462 MHz and 467 MHz main channels, 50 watts is the legal limit for mobiles, repeaters and base stations.  Fixed stations are limited to 15 watts. (A Fixed station is defined as a station at a fixed location that directly communicates with other fixed stations only.)

 

Second, on the 462 MHz interstitial channels (the channels between the main channels) stations are limited to an effective radiated power (ERP) of 5 watts, witch means the final power amplifier (PA) will likely need to have much less than 5 watts of output power.  This applies to mobiles, hand-helds, portables and base stations.

 

Then, to make things even more complicated, on the 467 MHz interstitial channels, stations are limited to an effective radiated power (ERP) of 0.5 watts, witch means the PA will likely need to have much less than 0.5 watts of output power.

 

So, be very careful on what frequencies you opt to use an amp on.  Frankly, I wouldn't spend the money, I would just get a new radio.  Quality UHF amplifiers are much more expensive than a radio that runs up to 50 watts.

[berkinet]

Ditto what @marcspaz said.  And, I'd ask, what is your use case?  Do you have a portable you want more power output from?  Are you talking simplex to one station, or many? Are you using a repeater?

 

Another thing to consider is the receiver. If you hook up a cheap radio, with a low quality receiver, to a 50 watt amp you will have a giant alligator... Big mouth, tiny ears. You will probably not hear 1/2 the people responding to you, and the half you do hear, you would probably hear without the amp.

 

Honestly, if you really need the power, you would probably be better off looking for a good quality 40 or 50 watt mobile radio. Personally, I would look at a used piece of commercial equipment - you will get a much better receiver than any mass-market Part95 certified radio. . You will easily find plenty of Part-90 radios, and if you care about certification, Part-95 radios are also available.  This topic is commonly addressed on the MyGMRS forum. Search through the threads for Kenwood, Icom, Motorola, and Vertex to see what might work for you.

[shevo7385]

Well thank you for the replies. Do yous have any product recommendations? Also, I understand the alligator example. But do they have any receiving amplification techniques or products out there to boost signals coming in?

[berkinet]

A receiver amplifier will raise the level of the received signal, but not the quality, and will not help the problem. The way to improve incoming signal quality is to use a better antenna or one with more gain.

 

As for product recommendations, do you mean for a radio, or an amplifier? If you mean radio, then please look through the forum topics there are many posts with reviews and suggestions. If you want an amplifier suggestion, I have no idea. I don’t use them.

[Radioguy7268]

I'd tell you that an "inexpensive amplifier" is really just a broadband noise generator. Yes, your meter might now read 50 watts - but it won't show you that you're not only putting 50 watts out on your desired frequency - you're also putting out some unknown amount of spurious energy out on adjacent frequencies (and multiples of your frequencies) - potentially interfering with other systems. Worse yet, those cheap amplifiers put out enough spurious noise that it will probably interfere with your own receiver - making that alligator system even worse.

 

You might find some used TPL or Henry amplifiers in the less than $200 range. There used to be a ton of Motorola vehicular repeater amps being sold on eBay that would do 40 watts - but most of them were VHF. I'd be very wary of using any amplifier with a CCR radio.

 

There's 100 ways to make your system talk better, and 98 of them don't involve an Amp.