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Thread: Cheap UHF Repeater??

  1. #11
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    Go to and do a search for the member name CB Rambo. See what you think.
    Last edited by KINGCHIP; 02-20-2014 at 06:37 AM.
    Yea, though I walk through the valley of the shadow of death, I will fear no evil:

  2. #12
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    Sounds like him!
    Last edited by KINGCHIP; 02-20-2014 at 06:38 AM.

  3. #13
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    Would this work for what we're doing? Put it in an ammo can with an extended battery and an external antenna? Place it in the middle of our AO.

    http://www.ebay.com/itm/Simplex-Repe...-/371008546222

  4. #14
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    You want advice but refuse to get licensed and admit to RF stomping? Pound sand.

  5. #15
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    Quote Originally Posted by AgainstTheGovernment View Post
    Would this work for what we're doing? Put it in an ammo can with an extended battery and an external antenna? Place it in the middle of our AO.

    http://www.ebay.com/itm/Simplex-Repe...-/371008546222
    In my experience Simplex Repeaters Suck

    Since you are not concerned with legalities and since you are using the Baofeng UV-5R (which is a dual band radio) a cross band repeater would probably be the cheapest way to go.

    The New $80 Puxing PX-UV973 http://www.amazon.com/PX-UV973-shipp.../dp/B00IA9TNVU supposedly has a true cross band repeating function. I have not personally tested out the cross-band repeat function of the PX-UV973, but if it works as advertised, I can't think of a less expensive cross-band repeating radio.




    Obviously a crossband repeating radio will not be as good as a true repeater, and I cant speak to the longevity of using a PX-UV973 but it will be less expensive than a "real" repeater and I bet it would work much better than the Simplex repeater you posted a link to and be less expensive. The simplex repeater will require a radio to work so the cost of the radio+simplex repeater will be more expensive than using one single PX-UV973

    Without a HAM license, I'd probably stay off HAM bands and go with MURS to GMRS. Some HAMs make it their mission in life to DF illegal operations and notify the FCC

    You'd program your UV-5R radios to transmit on VHF (MURS ) and receive on UHF (FRS/GMRS) or vice versa, then use the PX-UV973's cross band repeating function as a makeshift repeater.

    Add an external power adapter for the PX-UV973, a small 40 watt solar panel, a charge controller, and a 12V AGM battery, and you'd have a very simple and inexpensive cross band repeater that you could run indefinitely off a Sub $200 solar setup
    - $10 Power adapter http://www.amazon.com/Generic-Batter.../dp/B00DC1P50Y
    - $60 40 watt Solar Panel http://www.solarblvd.com/Solar-Panel...duct_info.html
    - $30 Charge Controller http://www.solarblvd.com/Charge-Cont...duct_info.html
    - $70 AGM Battery http://www.amazon.com/UPG-D5722-Seal...ywords=ub12350


    Antenna selection will be very important. For every 3 dB gain/loss you will either double your power, or lose half your power. I'd probably opt for something like a 6 dBi "Slim Jim" antenna. (the PX-UV973 is rated at 5 watts but would effectively be 20 watts with a 6 dBi antenna)

    If you can get your antenna up to around 25' that should easily cover 10 to 15 miles in every direction from the repeater. The taller the repeater antenna, the farther out your repeater will reach.

    You can DIY a Slim Jim antenna tuned to the transmit frequency of the PX-UV973 or if you don't want to DIY your own antenna they can be found on ebay pretty cheap. You'd want to ask the seller to tune the antenna to "commercial" frequencies for MURS to GMRS use if it's listed as 2 meter/ 70CM
    - http://www.ebay.com/itm/VHF-UHF-Slim...item4ab94ae16d this one comes pre-tuned to MURS/GMRS
    - http://www.ebay.com/itm/2-METER-70CM...item2c7a81bac9

    You could run a system like this with your PX-UV973 at the top of the antenna pole right under the antenna (in a vented but rain shielded box), this would make for very low losses from your PX-UV973 to your antenna and reduce Coax cost, but your PX-UV973 would be inaccessible.

    If you run a system with your PX-UV973 at ground level (as is usually done) Coax selection will be very important. I'd probably recommend LMR 400 Coax because it is very low loss compared to RG-58A, it will cost more (around $1 per foot) but with a low powered system every dB lost matters A LOT http://www.universal-radio.com/catalog/cable/coax.html

    However, if it were me and I was building this for a SHTF I'd opt for a real repeater if at all possible

    ----------------------------------------------------

    If you want a true repeater

    There are many examples of building GMRS repeaters inexpensively with old GM300 radios (which can be found on ebay for under $50 per radio). Check out this page http://www.repeater-builder.com/moto...rac-index.html it has a lot of info on building a repeater with the GM300 radios. The only problem is that they are a PITA to program, they require Motorola CPS so you're better off buying a radio from someone who can program it for you

    Ready to run GMRS repeaters can be found on ebay for $300 to $500
    - http://www.ebay.com/itm/Motorola-GR3...item4ad0919a4f
    - http://www.ebay.com/itm/Motorola-UHF...item232f166185

    But you will still need to buy an antenna duplexer if you plan on using one single antenna

    Lastly, if you go with a real GMRS repeater the GMRS license isn't expensive, just sayin, it could save you a hassle down the road......again your choice.
    Last edited by Tdale; 02-20-2014 at 05:48 AM. Reason: Fixed link
    Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.

  6. #16
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    Im running UV5rs on Murs and GMRS, and even FRM frequencies, works great their. Take Tdales advice and go that route.

  7. #17
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    Quote Originally Posted by AgainstTheGovernment View Post
    Would this work for what we're doing? Put it in an ammo can with an extended battery and an external antenna? Place it in the middle of our AO.

    http://www.ebay.com/itm/Simplex-Repe...-/371008546222
    I'm looking at this one. The voice mail option might have some use, plus there's a set of jumper pins you can change from 0 to 3v remotely via a DTMF code. Attach a relay to that, and you could turn on/off just about anything you wanted remotely. Like the ammo can idea.
    Everything marked, everything 'membered. You wait, you'll see.

  8. #18
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    Default Re: Cheap UHF Repeater??

    Quote Originally Posted by marked View Post
    I'm looking at this one. The voice mail option might have some use, plus there's a set of jumper pins you can change from 0 to 3v remotely via a DTMF code. Attach a relay to that, and you could turn on/off just about anything you wanted remotely. Like the ammo can idea.
    I agree that if you are going to go the simplex repeater route the Argent Data simplex repeater would be the way to go.
    Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.

  9. #19
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    Againsthegovernment -

    I will make it as plain as I can.
    The reason why we have rules is because we use those rules to protect the people who rightfully so are licensed to use those frequencies so that their communications are not interfered with.

    Amateur Radio operates on a secondary basis on the 70 CM bands - if the government so chooses, they can in fact take those frequencies back, which our duly elected President tried to do just a couple of years ago when he instructed the FCC to sell those frequencies to the highest bidder - cell phone people.

    The GMRS - is a set of frequencies that are regulated by the Federal Government, is designed for use by the government, but allows normal everyday citizens to use - with a license.
    The loop hole - enclosed with every bubble pack radio - should be a disclaimer that states - do not use these radios on the GMRS Frequencies without first applying for a GMRS license.
    Because the radio also operates on the Family Radio Service Frequencies - with one half of one watt of power, and because the radio does not come equipped with a removable antenna, and the radio would be damaged if it was taken apart and modified so it could use a higher gain antenna - the FCC looks the other way when the manufactures sells them..

    The Buisness Radio portion of GMRS has been removed from the GMRS, there was some licenses that were renewed / grandfathered in, but when the grandfather clause expires - the person for whom the license was written dies - they will not be renewed.

    Basically the government does not want repeaters on the GMRS, mandates that all radios that uses the GMRS frequencies be Narrow Banded Emissions only, but did make a provision for the REACT people - Since REACT at this time does not use any type of digital communications - packet - along side of their analog phone communications.. This waiver was granted because REACT does serve a legitimate purpose and their organization is so poor that if they were mandated to Narrow Band all of their radios - it would probably cause some of their organizations to close.

    A FM ( Frequency Modulation ) radio signal has many side bands - uses a term called Deviation, where as a Amplitude Modulation signal uses Amplitude - the level of sound and two side bands for its signal..
    A AM signal is very easy to modulate and demodulate - modulation is the intelligence placed upon the carrier. The carrier for the most part does not do anything except waste power, you can suppress the carrier or one of the side bands or both the carrier and the side band - which was what was done with the CB radio wars of the 1960's - 70's.

    The Problem with FM is that the harmonic's of the original signal can be as strong as the original signal.
    Drive up next to a large commercial FM radio tower and observe how many places along the dial of your FM radio you can hear the FM radio signal. All signals reduce at the square of the distance away.
    Because the third harmonic is almost as strong as the original signal and because the third harmonic is within the band of the original signal - the two will interfere with other things - other radio services.

    The only radio service other then commercial that uses AM is aircraft.
    You might read from time to time about a airport that was interfered with by someone with a CB radio and amplifier.

    In amateur radio, in order to repeat a signal, you either have to have two radios - one that receives the signal and then sends that signal to another radio that retransmits it, or you have to have a radio that receives it and then retransmits it - parrots it after all is said and done.

    If the receive radio and the transmit radio are in the same band - then the proximity of the two antenna's has to be placed upon a tower in such a manner that the separation between the two antenna's is sufficient enough that the one signal being transmitted doesn't back feed into the one receiving.
    The way they usually do this is with a cavity filter, a can - as some people puts it.
    The Cavity Filter is a device with steep skirts that only allows one frequency in and ignores all of the other frequencies around it. It takes 4 or 6 filters to remove the unwanted signal.
    The size of the cans is usually dependent upon the frequency they are designed for.

    A 6 meter - ( 50 MHz ) cavity filter is 6 feet tall, a 2 meter cavity filter array is around 30 inches and weighs 60 to 100 lbs. A 70 cm filter might weigh 10 lbs.

    The problem with what you want to do is that you do not understand the band plan or what other legal services you might be interfering with. You think that all you have to do is pick out any old frequency that your hand held can do - that sounds quiet to you and that you will be ok.

    Many of the 70 CM frequencies are unpublished and used by amateurs and other radio services as a type of a back haul frequency between repeaters - sometimes called a remote receiver, or is used as a control frequency to control their legally coordinated repeater.

    With Amateur Radio there is no rules against someone building their own repeater and putting it up on the air, but there is rules against letting people use their repeater that is not a licensed amateur or Licensed GMRS operator.
    Furthermore - the FCC requires that the repeater identify once every 10 minutes either by voice or by CW ID - which helps the people legally entitled to be on those frequencies to identify you if you are causing harmful interference to their legal equipment - since their equipment is coordinated and certified to be on those frequencies.

    You are not the only people on those frequencies - just because you don't hear anything does not mean that they are not there.
    450 - 470 includes police, fire, ambulance and commercial radio services in my area of the country.

    We had several incidences of contractors that did not understand the band plan in Western Pennsylvania that decided to put up radio equipment that thought that there would be no conflict between their equipment and everyone else.

    When the State Police started hearing stuff on their frequencies that did not belong there and could not use their frequencies for emergency communications they got upset and called both the FCC and the ARRL.. A mandate was issued to Fox Hunt those harmful transmitters and put them off the air - basically a license for anyone with a radio to go look for them and damage them any way they saw fit.

    Coaxes were chopped with axes and transmitters were smashed with sledgehammers.
    The normal fine is about $16,000 per a day.
    Much more then what I believe that your group can afford to loose.
    And if you get caught operating on those frequencies without a license, you can pretty much kiss your butt good bye along with the chance to ever apply for any type of license for any licensed radio service.

    When they tell you - you cannot operate any wireless radio equipment from that point onwards - that will include CB radio and your bubble back radios you thought were immune from getting a license for.

    The problem we are having right now is that the manufactures are selling these all band Beofangs and Woushuns to anyone without a license or any knowledge of radio and these people are setting up on bands for which they have no right and are causing harmful interference to licensed radio services.
    This is going to cause much grief somewhere down the road and is going to cause your group problems due to the fact that what you are trying to do - you are trying to do in secret, but you are going to call attention to yourselves when you start broadcasting a stronger signal a longer distance.

    The soil conductivity beneath the antenna and the gain of the antenna plays a more important role then just the power output - ERP of the transmitter.
    1 WATT atop a 1000' tower to a receiver atop another tower 1000' tall would be line of sight at 36 miles - which wouldn't be much different then you talking to a friend of yours 1000 feet away on the ground.
    Its not the amount of power that you produce, it is the way that the signal is propagated.

    This is the basic reasoning behind making people get licenses and having license examinations for people that wishes to become licensed radio amateurs.
    A Technician Class license holder can operate a transmitter on most UHF / VHF bands up to 1500 watts.
    Although when you produce more then 50 watts - you have to take exposure level readings of everything in the neighborhood - can't expose other people to those harmful power levels.

    This is the part that everyone forgets when they get an amateur radio license after attending a ham in a day class. Even when you are licensed to operate in the band, you still have to know all of the rules to operate in that band. It isn't just get a license and get on the air and do as you please - like the CB radio...

    CB radio by the way - the two radios and antenna's would have to be about a mile apart - not to interfere with each other - if you wanted to make a repeater that did not use a duplexer filter.
    Those cavity filters would be twice as big as the 6 meter duplexers. - I never saw a set, but I would figure they would be about the size of a 80 gallon hot water tank!

  10. #20
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    is it just me, or did anyone else not read beyond the first line of that wall of text. I mean we all know what it's going to say anyway.

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