900MHZ Repeater for the Motorola Radio

If anyone is interested in a repeater for their DTR radios, I stumbled upon this site tonight that has one. It is rather expensive, as all repeaters are. http://www.canewirelesspro.com/products.html

Thanks, Lonny!

Wayne Phang is a great guy and very knowledgeable about DTR radios.

Interesting. Since the repeater is built around modified DTR radios I assume it doubles the voice delay??

Yes, it does. I spoke to Wayne about this specifically and he confirmed that it doubles the latency.
I was considering getting this before I had a lot of experience with the DTR radios, but once I started using them, I found that even without a repeater, the range indoors on my DTR radios is even better than any of the analogue 4-5 watt radios I regularly used in the past, so it ended up that I didn’t need a repeater.

However, if you need it, you need it, and the latency would probably not matter.

Has anyone tried to use two radios and a repeater box like this one - http://www.amazon.com/Sangdo-Repeater-Motorola-PRO1150-PRO2150/dp/B016LUKZVG/ref=sr_1_1?ie=UTF8&qid=1445895029&sr=8-1&keywords=dtr+repeater

If so, any luck or any issues that arise? I’m assuming that you’d need to figure out a way to clone the ID on both radios?

That repeater box looks interesting, it’d be cool to see if you could make a portable repeater kit with it

I actually purchased this repeater box to lay back for time of need. I have not had an occasion to use it, and had not considered the fact that a radio would have to be cloned. I am guessing that as long as both radios are programmed the same, one would receive the signal and the other would resend it. Maybe I am wrong on this. If I get the time I will try setting this up to see how it works. This unit is so inexpensive, having one laid back for time of need made sense to me. However, if your going to need a repeater for the long haul, buying the above mentioned repeater makes more sense than using this box and maintaining two radios.

It looks like it’s just a speaker/mic connection, so no “channel” information would be passed. It would only be useful to repeat on one single channel, since no matter how the call was received on the receiver radio, it would transmit only on whatever channel the transmitter was already set to. Limits it’s usefulness.

That’s a good point. Does the Cane Repeater Box have the same limitation or does it pass along the channel information as well?

Actually I might have found the answer already, it looks like it might have the same limitation.
I found this in the description of a listing for the Cane unit -
“Only repeats one Public or Private group. Additional DRX repeaters are required to extend more groups.”

Today is a dreary nasty day with plenty of free time on my hands, so I set out to play with this repeater box “OUTSIDE”. By finding the outer limits of a mobile unit back to base, we set up two radios hooked together via the repeater box. We positioned the receiver radio higher than the transmitter radio (as far apart as the lines would extend with the receiver radio on the back side of a telephone pole facing the outer limits of our range and the transmitter radio on the opposite side facing the base station). Once these two radios are set up we drove in a straight line away from the base radio with the pole holding the repeating radios between us. We actually extended our outer range by about a mile and a half. This mile and a half contained some hills, trees and was a not a flat open terrain. A good flat open terrain may give you an ever greater extended range.

One thing we found was the latency between the radios was also greatly extended, but not really a nuisance because the few seconds delay is by far much faster than traveling back to the base station to deliver a message. All in all, using this small repeater box in conjunction with two radios works really well for temporary use to extend your operating range.

As noted, you are limited to just one channel when these are used. However, if you were simply trying to extend your range for a particular operation or task, this little inexpensive repeater box works perfect, and much cheaper than the bigger designated eleven hundred dollar repeater box. If you were looking for a permanent repeater operation, using the small repeater box with two radios really would become a nuisance to use as you must maintain two radios. However, if your simply looking for something to occasionally extend your range, and have a couple of extra radios idle, this is a very inexpensive way to accomplish your goal.

Very cool.

It seems to me there might be an issue if the 2 radios are too close together that they both receive the transmission from the far-away radio. Since both are receiving, the one wouldn’t be able to transmit to the other I would think. Should you be changing the settings on the transmitting radio so that it doesn’t receive any transmissions directly?

Interesting. I love this forum.

I am impressed that your tests showed about a mile and a half increase in range over straight walkie-to-walkie.

I know one can’t really compare a $30 temporary cable to a $1200 repeater because the repeater includes two DTR radios plus all the circuitry, but I am sorely tempted to try this. I usually have a couple of radios not used and my only application would be temporary use anyway.

I would LOVE further reviews of this solution!


I separated the two radios by the length of the two cables, which is approximately six feet. I also placed the one I was using to receive my new extended transmission on the side of the pole facing outward to where I intended to go. I positioned the radio I intended to feed back to our base on the opposite side of the pole and approximately six feet below the one on the opposite side of the pole. In the small amount of literature that came with mine it showed the receiving unit higher and the transmitting unit lower. This seemed to work for me fine. I also found on the internet a place where you can purchase cables that extend the distance even further between the radios. One example of this would be, if you wanted one radio to extend the range into an underground area from outside.

One note: I found the outer limits to the radio I was talking back to the base on, then backed up roughly twenty feet to the utility pole nearby. I set the repeater up on this pole, in the fashion mentioned above. I backed up into the original operating field for two reason. Number one I did not want to have the transmitting radio to be operating on the fringe of the base to mobile field, and number two, roughly twenty feet back into the range field there was this nice utility pole just waiting to be utilized.

I honestly did not need this repeater box, but it was so inexpensive I wanted one laying around in case a need ever arose to want to extend the range. One example of this may be a time of chaos where your fortifying a survival compound and maybe sending a scouting party out farther than the normal range of what two radios would be. Having this repeater box possibly gave me options I may not have otherwise. I am a person that likes options.

So if I am reading this correctly, the downside to these inexpensive repeaters on the DTR series is that they MUST be operated on the very fringe of reception. The receiving radio must be higher to be just inside the fringe of receiving, and the transmitting radio must be lower to be just outside the fringe of receiving. This is a function of how the DTR radios don’t do duplex or whatever you call it, when the radio receives on one frequency and transmits on another. The cheap repeater boxes are designed for the typical Baofung crowd, where one can receive on one frequency and then transmit on another, meaning the repeater box can be easily inside the radio range because the transmitting radio won’t receive the signal anyway because they use a frequency offset.

This changes the usefulness for me. By the time I walk to the far reaches of the range of my DTR radios and set up a temporary repeater, I might just as well have walked closer to be within range anyway. I can see it for more semi-permanent situations, but not for just temporarily throwing two radios out near the fringes to extend range. In this case, the very long range of the DTR radios is a bit of a detriment to setting up a cheap repeater.

Thanks for explaining that clearer for me. I think I will pass on this. (Not to mention, getting those cables - or the Sansonic equivalents - into Canada is a LOT tougher.) Finding exactly the right hydro pole at the exact right distance away just won’t work well for my needs. I guess one could park their car at exactly the right spot but you run into the same problem of the DTRs being TOO good.

Perhaps one could explore a 1/2 wave antenna on the receiving radio and a 1/4 wave antenna on the transmitting radio. That would help to prevent the transmitting radio from hearing the signal, but again, you would have to find the fringe limit for this to work.

Hopefully, I have all this striaght in my wee pea brain.

Yeah, it seems to me that the Transmitting radio in the linked pair would need a “Transmit only” mode where it can’t receive on the channel it transmits on.
Perhaps that’s the “special sauce” that’s in the Cane product.


I believe that this inexpensive repeater box could be set up anywhere in range to the base unit, and work just fine. In the test above that I did, I was simply trying to see what the maximum distance from base I could get with a handset. In order to do this, I CHOSE to set up my temporary repeater system close to the fringe area, thus allowing me to proceed further out past the normal distance. In my case in a hilly and tree lined terrain I was able to EXTEND my range back to base by about a mile and a half. I thought for something temporary and inexpensive, this was an impressive distance. By setting this repeater up half way between your base and the fringe area, I am guessing you would only have roughly a mile and a half distance from the repeater to the outer limits of range. setting the repeater up on the fringe area simply EXTENDS the range out about another mile and a half.

I set the repeater up like the literature showed that came with the repeater box, and that was with the receiving unit higher than the sending unit. I also separated them by about six feet which was the maximum of the two cords. I also placed the higher one on the side of the pole facing the area I intended to travel. The lower one faced my base radio. I believe this setup acts more like a relay station.

To be certain this is surely a temporary fix to enable one to achieve a greater distance. I seriously doubt that anyone would even try to use this for a permanent setup. One of the things I envisioned this repeater doing for us was to enable a hunting party to venture further away from base and still be able to stay in radio range. This would be a temporary use and just an example of what I perceived this box to be able to do. I am sure there are many more temporary situations others may be able to employ this box for. We do use some of our radios while hunting in the fall, and normally get along fine, as long as we stay in range. This repeater box setup will enable us to drift further out and still be in range of our base camp.

Thanks for the further info. I still see problems on how to stop the transmitting radio from receiving the signal if both radios are within range. I don’t know if the repeater box is sophisticated enough to block that. The DTR radios don’t do duplex channels, which is how they get away with it on the cheap Chinese Ham radios. I guess the only way to test this is to find a place where both radios are easily within range of base camp, but a remote radio is out of range, then hook up the cables to see if that extends the range to the remote. There has to be a way electronically to prevent the transmitting radio from receiving the signal but I just don’t think these cheap repeater boxes can do that.

I would love to be proved wrong though, as I envision a simple temporary repeater operation set up exactly the way you describe. Maybe on the next warm fall day, you can do more tests and let us know.

[EDIT] I thought I’d created a new thread, but wound up replying to this one instead. Sorry for bumping an old one.

I thought I’d share my experience making a DTR “repeater” with the Argent Data Systems ADS-SR1 simplex repeater.

For anyone who’s not familiar, a simplex repeater is a store-and-forward device that records an incoming transmission and immediately re-transmits it once it has ended - so you hear your own transmission repeated back to you, but hopefully so does the station who couldn’t hear you direct. Using a simplex repeater can be a little bit annoying and takes some getting used to, but it’s better than no comms if you’re in a place where you need the extended range.

The key to making it the least annoying for users is to not trigger the simplex repeater unless you know you need it. My DTR system is small (<10 units) so we don’t typically use talkgroups. Just one big group for everyone and the occasional private call. What I’ve done with the repeater is program the radio attached to it to be a member of the “Repeat” talkgroup only. Every user’s radio is a member of both the “Repeat” talkgroup and also a “Normal” talkgroup. If a user places a call in the Normal group and the station he’s calling is within range, the repeater stays quiet and communication proceeds as usual. If the station he wants is out of range, he can switch to the Repeat group and the repeater will re-transmit his call.

I have the ADS-SR1 and a stripped-down DTR550 in a Pelican-knockoff small weatherproof box, attached directly to the base of a Laird FG9026 antenna. This whole assembly can be easily hoisted high up in a tree with some line thrown over a branch, and significantly extends the potential range of the system.

One useful thing I learned in putting this together than might be useful for anyone else interfacing a DTR to some external audio circuit: It turns out there’s +2V DC between the speaker return (3.5mm sleeve) and the mic return (2.5mm sleeve) on the DTR, which is a problem if you’re plugging into a device that shorts those internally (as the ADS-SR1 does). A 0.1uF DC blocking cap spliced into the speaker return wire between the DTR and device solves that problem nicely.

I’ve still got some playing to do to tweak the audio levels and simplify usage. Just thought I’d throw this out there in case anyone might find it useful.

Thanks everyone. Lots of useful information