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Thread: I have a no-experience question about VHF/UHF repeaters.

  1. #1

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    Default I have a no-experience question about VHF/UHF repeaters.

    I have a coworker whoís a ham and who lives about thirty miles from me over pretty flat ground. Both of us have handhelds, and live in areas with repeater access.

    Iím thinking that the way to talk to him would be for me to transmit on my repeaterís uplink freq and receive on his repeaterís downlink freq, and for him to transmit on his repeaterís uplink freq and receive on my repeaterís downlink freq. Did I explain that correctly?

    But the repeater articles Iíve read seem to reference situations where one guy has a handheld and is using a repeater to transmit to another guy who has something more capable and powerful, and who can transmit directly back to the first guy.

    So...without concentrating on the low-level specifics of connecting to repeaters...whatís the big picture? How are repeaters actually used in the real world for two-way communications?

    Note: I have no license yet (thanks, COVID!), so I canít transmit yet, but I will in September.

  2. #2

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    A repeater generally runs with a 600 KHz offset. That means that it receives on say, 146.100 MHz, but would then transmit on 146.700 MHz. Because of this offset, a repeater can receive and transmit at the same time. Handheld radios have this offset option available. So if you and your friend wanted to talk, You would "both" transmit on the repeaters receive frequency and receive on the repeaters transmit frequency. Of course, you would take turns talking and listening.

    Most modern repeaters are keyed by a sub-audible CTCSS tone. These tones are generally below 300 Hz. Again, most handheld radios have this tone capability. I do have some old 2 Meter FM transceivers, where the tone circuit is optional. However, they can still be used "simplex".

    You can usually look up the repeaters in your area on the internet, to find the offset and the required tone. Note that, on a repeater, you need to keep your transmissions short. Repeaters are usually open to any licensed ham but are usually privately owned, so the owner sets the rules.

    However, you don't necessarily need to use a repeater. Once you get your license, try out communicating "simplex". IIRC, the 2 meter simplex "calling frequency" is something like 146.520 Mhz, for FM. Simplex is when "both" of you are transmitting and receiving on the same frequency and no tones are needed. You use a "calling frequency" to initially make contact, and then move to another frequency. That frees up the frequency for others to use.

    It has been a long time since I was on 2 Meters. In the early days, 2 Meters was all AM. There were a few FM stations around, but repeaters didn't exist yet. On a good day, my range was about 50 miles. I was only using a transmitter that ran 5 Watts Input. On a very good day, I could get almost 100 miles. But my antenna was in the attic of my parents house. The attic attenuated the signals a bit but the height helped thing out.

    Quote Originally Posted by dnwiebe View Post
    But the repeater articles I’ve read seem to reference situations where one guy has a handheld and is using a repeater to transmit to another guy who has something more capable and powerful, and who can transmit directly back to the first guy.
    If I understand that right, that sounds like a bad situation. The "handheld" would be transmitting on the repeater's receive frequency and listening to the repeaters transmit frequency. The "other guy" could possibly receive you on your transmitting frequency or the repeaters transmitting frequency. If the "other guy" then transmitted on the "handheld's" frequency, you wouldn't be able to hear him because your receive is offset. For you to receive him, the "other guy" would have to transmit on the repeaters transmit frequency. The "other guy" shouldn't be transmitting on the repeaters transmitting frequency.

    But maybe the original article says something different.
    Martin, K7MEM
    http://www.k7mem.com
    Ash Fork, AZ - 60 miles from the Grand Canyon on Rt-66. Elevation 5,300 ft.

  3. #3

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    This is probably the best explanation of repeater operation I've seen:

    http://www.alpinelakes.net/uploads/2...lstein__1_.pdf

  4. #4

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    Simply put....

    A repeater is a transmitter and receiver combination that repeats what is on one frequency and puts it on another frequency without anyone there to operate it. There is nobody at the repeater site and everyone in range has the ability to use it. There is an uplink frequency (what the repeater listens on) and a downlink frequency (what the repeater re-transmits it on). This happens simultaneously. In order for a transmitter and receiver to share a common antenna, the transmitter and receiver must be on different frequencies (called an offset, the 600kHz K7MEM mentioned) and have special filters called duplexers so when the transmitter transmits, that power stays out of the receiver (or it would get fried) and the received signal stays out of the transmitter.

    Repeaters are usually installed at places with a tall tower so people with low power radios like handhelds can communicate with it and therefore communicate to anyone within range of the repeater. So, you see, a repeater is not something that you and the other person physically possess and operate, it is something that operates itself. Every user of the repeater will program their radios to transmit on what the repeater listens on and program their radios to receive on what the repeater transmits on. every radio is programmed the same way.

    Hope this helps.

  5. #5

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    A Repeater can operate on any sort of offset. .600 is just 2 meters - 145 - 148 mhz.

    Some use as much as one megahertz, and 70 cm might use as much as 5 mhz.

    Walkie Talkies are a total waste of time, if you want to talk to someone, buy a real ham radio, put up a tower and a real ham radio antenna, buy some coax and a power supply and operate. There is a group near me that talks daily on 146.565 and there is 10 - 30 miles between the closest and furthest away operators. I've heard them talking as much as 50 miles away while in my mobile and I've talked to them as much as 70 miles away - while visiting a friend that lives on top of a mountain.

    Walkie Talkies are for little kids and people that doesn't understand amateur radio, what it is we do or how we do it.
    If you are reliant upon repeaters you will also be reliant upon repeater owners and trustees that may or may not like what you have to say or how you say it. Repeaters were never intended to replace amateur radio, but to augment it by increasing the range of someone while mobile. its not mandatory that you have to use a repeater, most hams quickly graduates from that mindset and moves on to HF and simplex communications where you can talk to people from all over the world and not just someone in the same county or state.

    https://hamradioschool.com/how-far-c...ebUJ84RqOQM9I8

  6. #6

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    Thanks, guys. I appreciate the time you spent responding, and the gentle tutorial tone you took. But this is the low-level kind of stuff I already know about repeaters. I'm not interested in how the engine of the car works, or how the controls should be manipulated; I'm more interested in the rules of the road and the considerations one uses in choosing a route across town.

    All the stuff I've heard about repeaters so far--and read about in my radio's manual--assumes a situation where communication is happening like this

    A <-> R <-> B

    between transceiver A and transceiver B, with repeater R in the middle.

    But the situation I'm thinking of is more like this

    A <-> Ra <----------------> Rb <-> B

    where A and Ra are in one city, and B and Rb are in another, and you have a table like this:

    Code:
    can hear    A     Ra    Rb    B
    A           -     yes   yes   no
    Ra          yes   -     yes   no
    Rb          no    yes   -     yes
    B           no    yes   yes   -
    Briefly put, A and Ra can hear everything but B, and B and Rb can hear everything but A.

    In such a case, A and B would probably need to violate their radios' default repeater offsets, yes? If Ra was 145.29 down / 144.69 up, and Rb was 145.11 down / 144.51 up, then A would need to receive on 145.11 and transmit on 144.69 (offset of -420kHz), and B would need to receive on 145.29 and transmit on 144.51 (offset of -780kHz). Is that correct?

    I've never read or heard about anybody trying to arrange a repeater setup like this, and at least my radio is not set up to make it easy. Is it true that nobody tries this sort of thing? And if it is, does nobody try it because it's a stupid thing to try, for some reason that I haven't thought of?

    Thanks again, guys.

    Dan

  7. #7

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    Quote Originally Posted by R2D2 View Post
    Walkie Talkies are a total waste of time, if you want to talk to someone, buy a real ham radio, put up a tower and a real ham radio antenna, buy some coax and a power supply and operate.
    It's possible that I might someday. A full shack is pretty expensive, though, in money and in time and in modifications to property, and I have literally no experience. Amateur radio is a pretty wide vista, and I don't really have a specific idea of what I want to do yet.

    I have a vague idea that I'd like to operate on 6 meters at some point, and another vague idea that I'd like to work with store-and-forward techniques, at least learning them and possibly improving on them, bringing over some concepts from my day job. Both of those ideas might turn out to be stupid, for reasons I don't understand now.

    Right now, CQ and CQ DX don't particularly grab me, because I don't see the fascination in introducing myself to somebody just to log his location and probably never speak to him again. That, too, might turn out to be a stupid attitude, because I don't have the experience yet to understand what I'm talking about.

    So right now, before I get my license, a cute little walkie-talkie is just perfect for me. Eventually I'll hit on something I want to do that it doesn't let me do, and then I'll have a reasonably well-defined direction in which to expand a little. That seems wiser to me than just shelling out twenty grand for whatever equipment I can find in my favorite color. (I'm not quite that ignorant, but I'm close.)

    Walkie Talkies are for little kids and people that doesn't understand amateur radio, what it is we do or how we do it.
    What'd I say? Perfect for me!

    If you are reliant upon repeaters you will also be reliant upon repeater owners and trustees that may or may not like what you have to say or how you say it.
    Excellent point. Excellent.

  8. #8

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    Quote Originally Posted by R2D2 View Post
    A Repeater can operate on any sort of offset. .600 is just 2 meters - 145 - 148 mhz.

    Some use as much as one megahertz, and 70 cm might use as much as 5 mhz.

    Walkie Talkies are a total waste of time, if you want to talk to someone, buy a real ham radio, put up a tower and a real ham radio antenna, buy some coax and a power supply and operate. There is a group near me that talks daily on 146.565 and there is 10 - 30 miles between the closest and furthest away operators. I've heard them talking as much as 50 miles away while in my mobile and I've talked to them as much as 70 miles away - while visiting a friend that lives on top of a mountain.

    Walkie Talkies are for little kids and people that doesn't understand amateur radio, what it is we do or how we do it.
    If you are reliant upon repeaters you will also be reliant upon repeater owners and trustees that may or may not like what you have to say or how you say it. Repeaters were never intended to replace amateur radio, but to augment it by increasing the range of someone while mobile. its not mandatory that you have to use a repeater, most hams quickly graduates from that mindset and moves on to HF and simplex communications where you can talk to people from all over the world and not just someone in the same county or state.

    https://hamradioschool.com/how-far-c...ebUJ84RqOQM9I8
    you are the problem, not part of the solution

  9. #9

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    Quote Originally Posted by NicolaJayne View Post
    you are the problem, not part of the solution
    Aw, c'mon, let him go. I think it's cute when he does the grumpy-old-ham thing.

    Anyway, I'll bet he's got a fair amount of good experience to share.

    Why am I in such a good mood? Because I needed a haircut badly, and was just about to go get one after putting it off for way too long, when the Plague struck and all the barber places closed. And today, I finally got my haircut! I feel ten pounds lighter. It'd put anybody in a good mood.

  10. #10

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    Quote Originally Posted by dnwiebe View Post
    Thanks, guys. I appreciate the time you spent responding, and the gentle tutorial tone you took. But this is the low-level kind of stuff I already know about repeaters. I'm not interested in how the engine of the car works, or how the controls should be manipulated; I'm more interested in the rules of the road and the considerations one uses in choosing a route across town.

    All the stuff I've heard about repeaters so far--and read about in my radio's manual--assumes a situation where communication is happening like this

    A <-> R <-> B

    between transceiver A and transceiver B, with repeater R in the middle.

    But the situation I'm thinking of is more like this

    A <-> Ra <----------------> Rb <-> B

    where A and Ra are in one city, and B and Rb are in another, and you have a table like this:

    Code:
    can hear    A     Ra    Rb    B
    A           -     yes   yes   no
    Ra          yes   -     yes   no
    Rb          no    yes   -     yes
    B           no    yes   yes   -
    Briefly put, A and Ra can hear everything but B, and B and Rb can hear everything but A.

    In such a case, A and B would probably need to violate their radios' default repeater offsets, yes? If Ra was 145.29 down / 144.69 up, and Rb was 145.11 down / 144.51 up, then A would need to receive on 145.11 and transmit on 144.69 (offset of -420kHz), and B would need to receive on 145.29 and transmit on 144.51 (offset of -780kHz). Is that correct?

    I've never read or heard about anybody trying to arrange a repeater setup like this, and at least my radio is not set up to make it easy. Is it true that nobody tries this sort of thing? And if it is, does nobody try it because it's a stupid thing to try, for some reason that I haven't thought of?

    Thanks again, guys.

    Dan
    What you're proposing has already been done. I think your example makes it more complicated than it really is. In Southern California, there is a system of repeaters linked via a UHF radio link that connects four repeaters, two in California and two in Arizona. It's called the CALZONA link and is a joint collaboration between the East County repeater Association in San Diego and the Arizona Repeater Association. Anything that goes into one repeater comes out on the other three simultaneously without regard to offsets or frequencies. Four separate operators could hold a conversation, one on each repeater with no difficulty.

    There is also the WinSystem, a bunch of linked repeaters spanning the better part of the West Coast, California to Washington state. Most of these are linked via the internet, but the concept is the same as using a radio link.

  11. #11

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    Quote Originally Posted by K6CPO View Post
    What you're proposing has already been done. I think your example makes it more complicated than it really is. In Southern California, there is a system of repeaters linked via a UHF radio link that connects four repeaters, two in California and two in Arizona. It's called the CALZONA link and is a joint collaboration between the East County repeater Association in San Diego and the Arizona Repeater Association. Anything that goes into one repeater comes out on the other three simultaneously without regard to offsets or frequencies. Four separate operators could hold a conversation, one on each repeater with no difficulty.
    Okay, that's something I didn't know. Separate repeaters that all broadcast the same signal at once. On the one hand, that would make it really handy if you were the guy using the repeater; on the other hand, it would make it really annoying if somebody else was using the repeater and you had traffic waiting for it.

    Curiosity: the UHF links between the repeaters: are they on amateur frequencies or commercial frequencies?

    Of course, if my repeater and my coworker's repeater aren't in the same network, we'd still have to bodge together something like my example, yes?

    Thanks,
    Dan

  12. #12

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    Quote Originally Posted by dnwiebe View Post
    Okay, that's something I didn't know. Separate repeaters that all broadcast the same signal at once. On the one hand, that would make it really handy if you were the guy using the repeater; on the other hand, it would make it really annoying if somebody else was using the repeater and you had traffic waiting for it.

    Curiosity: the UHF links between the repeaters: are they on amateur frequencies or commercial frequencies?

    Of course, if my repeater and my coworker's repeater aren't in the same network, we'd still have to bodge together something like my example, yes?

    Thanks,
    Dan
    Most repeaters, linked or not, are open to all licensed amateurs. It's just a matter of courtesy that you wait your turn for a repeater, unless, of course, it's a life and death emergency.

    I'm unaware what the link frequencies are for that system.

    I'm not sure what you're trying to accomplish with your example. You mention "co-worker" so I assume you are both in the same general locale. One repeater with the proper placement would allow the two of you to converse with each other. And it really doesn't matter if it's yours, his or someone else's. Even if the repeaters are in separate cities (per your example) linking as I described in my previous post is how to accomplish that.

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