Posted: 3/8/2009 9:12:15 PM EDT
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I have four Motorola Talkabout HT's. They get the usual range, as you'd expect. I'm interested in improving that. I know I can't raise the output power or I'll kill the battery even faster than I do now. I had in mind adding a BNC antenna connector to the top in place of the stock UHF helical whip. Then I could run a Ham whip.That would sure add some range to the unit. I searched around but found no web pages saying how others have tried this obvious mod. Anyone here know about this stuff? Thanks! |
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well, its illegal as far as the FCC is concerned. FRS radios have fixed antennas.
You can mod an amatuer radio to work on these frequencies, but that also, is illegal. Will they kick in your door, shoot your dog, and handcuff the kids? Doubt full, but by law, its not ok. The VX-7r and VX-8r are easily modified to work on FRS bands, as are most amatuer radios. The 7r can be done by a software mod, and the 8r is a matter of unsoldering an SMT resistor under the battery. If you can solder on a bnc connector, you can unsolder this resistor. |
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I had in mind adding a BNC antenna connector to the top in place of the stock UHF helical whip. Illegal modification. The length of the antenna affects the radio's effective radiated power (ERP), which is limited by FCC regulations to a specific value. Using an external antenna with higher gain than a rubber ducky increases the ERP, which is illegal. Then I could run a Ham whip.That would sure add some range to the unit.
Ignoring any legal aspects, ham antennas are tuned for the ham bands - not for the FRS band. When you operate an antenna outside its design frequency, it doesn't work well - and the resulting high SWR may also smoke the radio's transmitter final amplifier as soon as you transmit. |
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Then I could run a Ham whip.That would sure add some range to the unit.
Ignoring any legal aspects, ham antennas are tuned for the ham bands - not for the FRS band. When you operate an antenna outside its design frequency, it doesn't work well - and the resulting high SWR may also smoke the radio's transmitter final amplifier as soon as you transmit. A 70cm ham band antenna will work fine, you should have an SWR of 1.5:1 or less. |
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just go buy a pair of GMRS radios with a 20 something mile range. And Some GMRS radios have antenna connections, But operating one without a GMRS permit is just as illegal as modifying a ham transciever. The FCC learned from the CB era, Make it a fixed antenna, unless you need a liscense, just so some joe blow can not connect a 10 meter( or 70cm for FRS) band amplifier and a yagi to the damn thing and wreak havoc nationwide. |
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Changing the antenna is going to have negligible effect on the range, there just isn't that much difference between a full ¼λ whip and the slightly loaded helical whip they are probably using. Now if you hacked in a coaxial cable connection and hooked it up to a 5dB gain mobile antenna or a yagi or something then you'd see an improvement.
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just go buy a pair of GMRS radios with a 20 something mile range. And Some GMRS radios have antenna connections, But operating one without a GMRS permit is just as illegal as modifying a ham transciever. The FCC learned from the CB era, Make it a fixed antenna, unless you need a liscense, just so some joe blow can not connect a 10 meter( or 70cm for FRS) band amplifier and a yagi to the damn thing and wreak havoc First: GMRS bubble pack handhelds probably have no real range advantage over FRS, certainly not "20 something miles". Second, amplifiers are probably the real reason for the fixed antenna restriction. |
| Those high mileage hand held radios sold at most stores get nowhere near the advertised range. A couple of miles at best under most conditions. Line of sight or over water will give better results. I've stretched one of the older 2 mile rated FRS radios to 4 miles, over water. |
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Outdoors forum. check the ham radio link. Does nobody look anymore? Don't send people who can't even read the enclosed directions to the ham forum with this tripe! 
"Hmm... I mean guys, with M16's costing over $10k, I noticed you could just remove the disconnector and you'd get full auto fire. I don't understand why nobody discusses this obvious mod" Yeah. Right. 
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just go buy a pair of GMRS radios with a 20 something mile range. And Some GMRS radios have antenna connections, But operating one without a GMRS permit is just as illegal as modifying a ham transciever. The FCC learned from the CB era, Make it a fixed antenna, unless you need a liscense, just so some joe blow can not connect a 10 meter( or 70cm for FRS) band amplifier and a yagi to the damn thing and wreak havoc nationwide. Please explain the bit about modding a ham txr being illegal? 
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Outdoors forum. check the ham radio link. Does nobody look anymore? Don't send people who can't even read the enclosed directions to the ham forum with this tripe!
"Hmm... I mean guys, with M16's costing over $10k, I noticed you could just remove the disconnector and you'd get full auto fire. I don't understand why nobody discusses this obvious mod" Yeah. Right. Sure he'd have been run out of the ham radio link, but that should have been the obvious first place to look for the information he was seeking. Obviously. Radio stuff in a radio forum. DUH!!!! |
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The FCC requirements for GMRS specifically disallow detachable antennas, and making improvements to crappy consumer gear is much more trouble than it's worth.
The answer you're looking for is called MURS, which basically opened up the use of former VHF business band radios and frequencies up to 2 watts for license-free use. These are much higher quality radios for not much more money, more powerful than GMRS, and allow the use of whatever antenna you like. See here for dry technical info. |
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moddifying it is not illegal, transmiting on the FRS band with a moded transciever is illegal. Ham radios are not type accepted for the FRS bands, VHF bands, or anything outside the amatuer bands.
This is why police departments/fire departments can not use moded VX-7Rs for official use on their liscensed frequencies. Some do, but its not legal. Now a life and death situation is a differint story, you can use ANY means of communication to save life and limb. |
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The FCC requirements for GMRS specifically disallow detachable antennas, and making improvements to crappy consumer gear is much more trouble than it's worth. The answer you're looking for is called MURS, which basically opened up the use of former VHF business band radios and frequencies up to 2 watts for license-free use. These are much higher quality radios for not much more money, more powerful than GMRS, and allow the use of whatever antenna you like. See here for dry technical info. no, GMRS allows detatchable antennas, and the .5 watt rule does not apply. FRS can not transmit more than half a watt, and must have fixed antenns. You can slap a yagi on a GMRS radio if you wish, and there are GMRS channels set aside for repeater use as well. If you operate a radio that has been approved exclusively under the rules that apply to FRS, you are not required to have a license. FRS radios have a maximum power of ½ watt (500 milliwatt) effective radiated power and integral (non-detachable) antennas. If you operate a radio under the rules that apply to GMRS, you must have a GMRS license. GMRS radios generally transmit at higher power levels (1 to 5 watts is typical) and may have detachable antennas.
http://wireless.fcc.gov/services/index.htm?job=service_home&id=family |
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The FCC requirements for GMRS specifically disallow detachable antennas, and making improvements to crappy consumer gear is much more trouble than it's worth. The answer you're looking for is called MURS, which basically opened up the use of former VHF business band radios and frequencies up to 2 watts for license-free use. These are much higher quality radios for not much more money, more powerful than GMRS, and allow the use of whatever antenna you like. See here for dry technical info. Full of incorrect information. GMRS has no restriction on detachable antennas, and up to 50 watt mobile radios for significantly more range than MURS. Vastly more choice in quality radios for the GMRS band as there are very few MURS type-accepted radios on the market versus essentially any LMR type accepted UHF radio which is legal for GMRS. |
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just go buy a pair of GMRS radios with a 20 something mile range. And Some GMRS radios have antenna connections, But operating one without a GMRS permit is just as illegal as modifying a ham transciever. The FCC learned from the CB era, Make it a fixed antenna, unless you need a liscense, just so some joe blow can not connect a 10 meter( or 70cm for FRS) band amplifier and a yagi to the damn thing and wreak havoc nationwide. Please explain the bit about modding a ham txr being illegal?
Easy Not-Class Type accepted..... can't legally use modified ham gear to run most public service bands, business bands, or CB either. Happens everyday, but isn't technically legal. Modding itself is not illegal, just using it outside the acceptance is. |
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The FCC requirements for GMRS specifically disallow detachable antennas, and making improvements to crappy consumer gear is much more trouble than it's worth. The answer you're looking for is called MURS, which basically opened up the use of former VHF business band radios and frequencies up to 2 watts for license-free use. These are much higher quality radios for not much more money, more powerful than GMRS, and allow the use of whatever antenna you like. See here for dry technical info. Full of incorrect information. GMRS has no restriction on detachable antennas, and up to 50 watt mobile radios for significantly more range than MURS. Vastly more choice in quality radios for the GMRS band as there are very few MURS type-accepted radios on the market versus essentially any LMR type accepted UHF radio which is legal for GMRS. My bad... I had FRS on the brain when I wrote that for some reason. But isn't it true that you can use any old VHF business radio on MURS without needing specific type-acceptance? |