# Handheld radio help



## Jango (Jul 13, 2008)

Anyone know of a good way to extend the tx/rx power of a handheld radio?  I have a Motorola HT750, and looking for a way to boost its ability w/o making it completely cumbersome to carry.  Any thoughts?


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## WuLabsWuTecH (Jul 13, 2008)

i'm not familiar with that radio, does it have a detachable antenna?


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## ffemt8978 (Jul 13, 2008)

Handheld radios are generally limited in power by FCC regulations depending upon what frequency range they use.

IIRC, UHF radios are limited to 4 watts, and VHF radios are limited to 5 watts.

Changing the antenna length won't increase the Tx power, and may cause problems on the reception end as antennas are designed for frequency ranges.


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## mycrofft (Jul 13, 2008)

*Not much to do generally.*

Make sure the battery is maintained as designed, don't yank on the antenna, and use it in an optimal area. Keep it in its holster to minimize droppage damage.
The old metal Slinky trick might work to extend reception, but it is ungainly and undignified and if you make metal-to-metal contact you could screw up your perfectly good antenna...it si good, isn't it?


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## MMiz (Jul 13, 2008)

You really can't expect much out of a handheld radio.  Get a good antenna, or go mobile.  I'd suggest asking the folks over at BatLabs.  They're Motorola techs who may be able to give you some tips.


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## Jango (Jul 13, 2008)

Thanks for the responses guys.  I take great care of the radio and battery(making sure to fully discharge it from time to time). I work for a volley dept and I hear everyone else except our dispatch, hearing tones for the pager is no problem...hearing my dispatch is the problem.  I can hear them on my bearcat scanner.....BARELY.....I was just hoping I could get a better antenna and increase my reception.  Thanks again for all the input.


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## MMiz (Jul 13, 2008)

What antenna do you have on it now?


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## zacdav89 (Jul 13, 2008)

It is almost always illegal to try to modify radios to increase range, one good way to help improve range the way you hold your radio. Most people turn their radios side ways or at a 45 when they talk in to it, if you want to get better range along with a good battery, hold your radio straight up and down when you talk, that was how the radio was designed to be used in the first place.


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## MRE (Jul 14, 2008)

zacdav89 said:


> It is almost always illegal to try to modify radios to increase range, one good way to help improve range the way you hold your radio. Most people turn their radios side ways or at a 45 when they talk in to it, if you want to get better range along with a good battery, hold your radio straight up and down when you talk, that was how the radio was designed to be used in the first place.



Replacing an antenna is not illegal and can do wonders for increasing range, but still being easy to carry is another matter.

The normal antennas found on handheld radios are sometimes known as rubber ducks, and are vertical antennas which radiate 360 degrees, broadside to the antenna.  The radio systems that EMS, along with police and fire have antennas that are all vertically polarized.  If you hold your radio at an angle, then it is no longer correctly polarized and you have reduced your range signifigantly.  Keep the antenna straight up and you will be maximizing the potential of the given antenna.

One reason that handheld radio antennas tend to perform poorly is beacuse a vertical antenna is designed to have a groundplane immediately beneath it.  A groundplane is a flat conductive surface which aids in directing the RF energy in the correct direction.  Since it is not practical to have a piece of sheet metal orthogonal to the antenna base, they go without it and live with reduced performance.

If the radio in question has a removable antenna, you may be able to find a longer (up to 3' sometimes) vertical antenna to replace the original that can be extended when needed and collapsed when not.  You will need to be sure that the antenna is designed for the frequency of operation and can handle the power that the radio puts out.  Using an antenna designed for another frequency can damage the radio.  A longer antenna will usually have more gain, but will not be a huge increase in performance.

I have never used a Motorola HT750, but I hear that the radio itself is not known for its TX and RX abilities, so the circuitry in the radio is just not designed really well and you may never be able to get excellent performance from it.


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## Jango (Jul 14, 2008)

zacdav89 said:


> It is almost always illegal to try to modify radios to increase range, one good way to help improve range the way you hold your radio. Most people turn their radios side ways or at a 45 when they talk in to it, if you want to get better range along with a good battery, hold your radio straight up and down when you talk, that was how the radio was designed to be used in the first place.



  I always hold the radio the right way.....I think my issue is the crappy antenna the city uses(pop 4,000 we are quite rural).


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## Jango (Jul 14, 2008)

KB1OEV said:


> Replacing an antenna is not illegal and can do wonders for increasing range, but still being easy to carry is another matter.
> 
> The normal antennas found on handheld radios are sometimes known as rubber ducks, and are vertical antennas which radiate 360 degrees, broadside to the antenna.  The radio systems that EMS, along with police and fire have antennas that are all vertically polarized.  If you hold your radio at an angle, then it is no longer correctly polarized and you have reduced your range signifigantly.  Keep the antenna straight up and you will be maximizing the potential of the given antenna.
> 
> ...




Right now all I have on my radio is the stock rubber duck and I have the frequency specs for it, I was hoping a taller/better constructed antenna would help....but then it could just be I live too far from our radio tower.


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## Jon (Jul 14, 2008)

Depends on when/where you are using the radio. Motorola sells mobile bases for their HT's that let you use the radio with an external antenna and power supply... and perhaps an amplifier too.

The solution may be a properly designed external antenna that you connect into at home.

Actually, a coat-hanger 1/4 wave antenna with a ground plane might work well.

Jon


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## MRE (Jul 14, 2008)

Jon said:


> Depends on when/where you are using the radio. Motorola sells mobile bases for their HT's that let you use the radio with an external antenna and power supply... and perhaps an amplifier too.
> 
> The solution may be a properly designed external antenna that you connect into at home.
> 
> ...



Depending on the service and license type, an amplifier is probably not permitted.  Generally each radio in a service is listed on the license along with its power output (usually around 5W for a handheld, 50-100W for mobile and fixed stations), so using an amplifier would be a violation.  Also, if you can't hear the other station then an amplifier won't help with that.

You might be able to get away with a very small groundplane, 2" diameter and still carry the handheld without too much trouble.  1/4 wave would be good, but hopefully you can find something a bit more secure than a coat hanger, at least if it will be carried.


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## Jon (Jul 14, 2008)

http://www.hamuniverse.com/2metergp.html

This was what I was thinking about. It is easy to make, but you do need some radio test equipment to make it well... however, if you DON'T transmit with it, you might be able to get away with it with a less-than-perfect SWR.

If you are on VHF 'Highband' the dimensions will be similar... then this could be hung in the house and attached in place of the "duckie" antenna when you are home. Of course... this is the radio whacker in me coming up with a solution that I might try. YMMV.

As for the amp... The set-up I'm thinking of I think counts as a "mobile"... because it is permanently installed in the vehicle, but you can take the portable out when you need it. I've seen some Chief Officers use rigs like these in their POV's


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## MRE (Jul 15, 2008)

Jon said:


> http://www.hamuniverse.com/2metergp.html
> 
> This was what I was thinking about. It is easy to make, but you do need some radio test equipment to make it well... however, if you DON'T transmit with it, you might be able to get away with it with a less-than-perfect SWR.
> 
> ...




Quick and easy way to do it if your inside is to get a magnet mount antenna and a metal trash can lid.  Stick the antenna on the lid and throw the whole thing up on the roof.  Done that more than a few times myself.

As far as handheld vs mobile, if you look up a license on the FCC website they list a number of radios of each catagory and by power output.  If your dept has 10 handhelds and 5 mobiles, and you use an amp to put out the power that a mobile does, technically you have 9 handhelds and 6 mobiles, which violates the license.  You would really have to check your own license to see if it has any "open spots" and then it still might not be completely legal if you do it yourself.


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## Jango (Jul 15, 2008)

Build my own antenna?  Hmm, sounds fun!  However....I don't think I will mount it on the car....I get enough grief rolling a PT Cruiser with a lightbar on it!  I think I might look around and consider my options, again thank you for all the input!


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