CB to GMRS Conversion?

Discussion in 'CB Radio Forum' started by russbrill, Jun 11, 2021.

  1. Ridgeline

    Ridgeline Road Train Member

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    I have monitoring the gmsr in my area for about 15 days, have the system hooked up to a tape recorder (reel to reel … yes a real one) that when there is activity it turns on and records what ever is being said.

    So for 15 days, it has moved one yard of tape and that was me testing it.

    I am a couple miles from US 23 and it is pretty business with cb traffic but nothing else.
     
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  3. Timin770

    Timin770 Road Train Member

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    I'm gonna run one of my gmrs handhelds up and down I-85 between ATL and RDU area, and possibly other parts of NC and SC. I don't expect a ton of traffic, but if you think about it there's not a ton of traffic on CB. This is just for evaluation and amusement

    Back to CB, back in my day there were no cell phones or pagers, so a lot of us had CB in our cars. "Breaker, where's the party tonight?" "There's a keg party up on Smith Road!"
     
  4. Timin770

    Timin770 Road Train Member

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    Screenshot_20210704-094118.png Seems to be a group of folks shouting back and forth on channel 20 here in Cherokee County GA. I'm hearing one dude clearly about 15 miles away.

    ***Edit obviously these guys on 20 are on a repeater somewhere. I am hearing traffic from Acworth, Jasper etc. It was virtually non-stop all day.

    There are three repeaters relatively close to me. I live in the bottom left corner of the attached screenshot. Holly Springs
     
    Last edited: Jul 4, 2021
  5. Night Stalker10

    Night Stalker10 Road Train Member

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    I wonder if the repeater you're hearing is owned by a radio or jeep club. That's one way most repeaters are paid for, with the club dues. For those who don't know this, some repeaters aren't necessarily open to the public, but most are. I don't know about gmrs. If they use a PL tone, you will have to figure out what it is, then program it into your radio before you go on your trip.
     
  6. Timin770

    Timin770 Road Train Member

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    IIRC all three of the repeaters shown on my map cost something or are "by permission"
     
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  7. handlebar

    handlebar Heavy Load Member

    Ummmm.......depending upon the average terrain, mountains on either side of the highway, weather conditions, conditions of the antenna(s), height above average terrain, and a host of other factors, then you may be right. 4-watts of 27 MHz to a +3dB antenna mounted up high and in the clear to a 50 watt transmitter to a +5dB antenna mounted under the same mounting conditions may well be a winner for the GMRS signal.
    A 4-watt signal on enough of a hill to have *nothing* in the path to a GMRS antenna nothing but dry air along the path between the two antennas should stand a fair change to have a conversation.
    Something to remember is that GMRS is mandated to use FM only, which virtually eliminates AM-type noise, like precipitation static, fuel pumps, lightning crashes, tire/road static, rusty load binder links grating on one another, wiper motor noise, electric window noise, and the like -- but only in the FM receiver. Since FM is not lawful on CB (partially because the bandwidth is about 4x what AM is, there's no way to *not* interfere with AM & SSB traffic on a couple of channels either side of a CB channel using FM. Plus you'll hear all manner of RF noise on your FM receiver from AM & SSB on adjacent channels, if your receiver is set for FM.

    GMRS (and FRS) are allowed a mix of FM bandwidths, depending upon the service under which they're operating. Properly licensed GMRS (the cost is just a pittance) allow for up to 50 watts transmitter output, +/- whatever gain (or loss) your base radio has on the end of your coax. Same for mobiles: 50 watts, +/- antenna gain (or loss). Several of the FRS channels (1/2 watt, integral antenna) --- no putting on a +6 dBi whip on a FRS handheld. The two upper MURS channels --- 154.570 and 154.600 -- allow 2 watt, a carryover from when they were FCC licensed "LPI" , or "Low Power Industrial" frequencies, intended for directing trucks around terminals, guard gate to admission offices, maintenance personnel running thither and yon on production floors fixing conveyer belts -- you get the idea --- short range, reliable communications within small-ish areas in freight yards or inside production facilities, car dealership lots.

    There is also a provision for "small GMRS stations". Limited to 5 watts output (to whatever directional antenna, as long as it's no taller that 20 feet AGL, IIRC). These were to either serve as "control stations" to talk through GMRS repeaters, the thinking that the repeater would not move not move, and a directional repeater would focus the majority of its output repeater at the antenna, thereby cutting down on co-channel interference. And a 50-watt GMRS "control station" would capture the repeater's receiver, keeping anyone else from being able to use the repeater. Remember, it's supposed to be a shared resource.

    I think that's all I've got. Full disclosure: I operate 3 business community repeaters, 2 interconnected (with the phone service), and a 5-channel 800-MHz interconnected LTR trunking repeaters. I've also installed 11 private repeaters for single users with many vehicles, because it was cheaper in the long run to own the whole system than to rent time on a shared ("community") repeater. And I spent 40 years as a field technician for Motorola, RCA, and GE, installing & maintaining microwave-linked repeater sites.

    And yes, I'm a Extra Class Ham, from 23 years when I had to be able to send and receive at 20 words per minute. Before that I got my Novice ticket when I was 9, General at 18, and Advanced at 19. For what it's worth these days, I also hold a Second Class Radiotelegraph License, now nearly defunct because Morse on the high seas has taken a back seat to GMDSS, floating distress buoys, satellite phones, and more and fancier ways to signal distress. My Second Class Radiotelephone license was changed to a General Radiotelephone License by Administrative Order some years ago, in order to simplify all the "Commercial Licenses" into one license to cover broadcast and private into one wall shingle.
    I can also use a superhetrodyne receiver and, with a couple of simple circuit changes, turn a receiver into a fairly weak emergency transmitter -- Morse only, and only a few miles range with a long antenna, but it someone is out looking for us, it's better than a fart in a windstorm.

    Hope I haven't bored you all to tears. As someone who's spent my entire life (first license at age 9, and currently 69 years of age, I've learned a whole lot of that used to be called, quaintly, "wireless."

    73
    dahdidah didadidit dadadididit didididit dahdit dahdidahdah dahdididahdit dididididah
     
    Last edited: Jul 5, 2021
    Reason for edit: Multiple typos -- that's what I get for trying to type at 1 a.m.
  8. Timin770

    Timin770 Road Train Member

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    Very odd, my reefer unit causes static on GMRS 19. I unplugged everything and then plugged back in one device at a time. The reefer is the problem. Thankfully no other channels are affected
     
  9. Night Stalker10

    Night Stalker10 Road Train Member

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    That's too bad. Unfortunately the radios filter circuit can only do so much.
     
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  10. Timin770

    Timin770 Road Train Member

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    All other channels seem fine. Can't imagine WTF the reefer can be throwing off to interfere with FM. Strange. ***Edit: I should mention that the reefer doesn't have to be running to interfere. It simply needs to be switched on, ie Sentry Mode. The radio also needs to be fairly close to the reefer control panel to get static. It might be OK if moved far enough away in the cab
     
    Last edited: Jul 5, 2021
  11. Powder Joints

    Powder Joints Subjective Prognosticator

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    I ran a MSS in Glendale CA for my fatherinlaw for a number of years, I also have a HAM radio License though I wont list my call sign here, and a General Class w/ radar endorsement, Worked for Advanced ELectronics also a MSS and for Jimmy at Lucky's 2way in Van Nuys,saw Motoroal go from Motrac's thru 900 Mhz Trucking, and worked with Pactel (Alan Cameron) on development of the SoCal infra-structure of Cell system, there test systems were installed into our repeater sites for testing and later on they purchased the mountian tops from our family.I still use a Motorola R2000 to tune radiios
    And still my opinion is worth about as much as the time and space it consumes, maybe slightly less.
     
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