Repeater elmer needed

[W3RB]

Here, in Honduras, a missionary-run hospital in the Northern, coastal town of Balfate used to have a more experienced ham who helped get them set up with two-meter rigs for them and the area's clinics, as well as a repeater so that everything would work together where the terrain would usually hinder line-of-sight communication. Unfortunately, the repeater stopped working AND the ham who had been helping left without ever fixing it.

About four and a half years ago, I came down to La Ceiba (about 35 miles from Balfate) as a missionary to help other missionaries with various logistical things, including computer maintenance and medical-patient logistics. Just before I came down, the doctor friend who had originally invited me asked if I would be willing and able to get an amateur-radio license to try to help him with communication among the clinics where he works. I did so, and eventually also got my Extra class license and became a Volunteer Examiner. Even so, my actual knowledge of amateur radio remains limited, and my practical experience is not much more than that of a novice.

The missionary doctors at the hospital, however, asked me to become their radio and repeater maintenance person, so that they may keep their focus upon running the hospital and communicating with the clinics. When I was there, a little over a month ago, they took me to the shack that houses their repeater, just so I could see the non-working equipment that is currently there. They believed that the existing setup had not be repairable and was not the appropriate equipment for long-term use, since it is really just an Icom IC-2000 mobile transceiver, a Radio Shack HTX-242 mobile transceiver, a CSI CS-800 interconnect and a four-cavity BpBr duplexer.

On a later trip, we found that equipment actually DOES still work. Apparently, it HAD stopped working, so they had just turned off the power to the shack. When we turned the power back on, everything was working again - probably indicating that the setup had protected itself by going into thermal shutdown originally, and that they had just never tried it again after it had had time to cool off.

Those mobiles probably are not good for the higher duty cycle a repeater could require, so the hospital is looking into getting a grant for something more appropriate. Even so, they want ME to be their maintenance guy, but that trip a little over a month ago had been the first time I had ever even seen a repeater, let alone been aware of the details of how one like this could be set up.

Thus, I am looking for someone to be an "Elmer" to me, given all the above. If nothing else, we know we already have a site, a shack, a tower and an antenna (along with the rest of the equipment I mentioned earlier), but I need some guidance in helping them determine the equipment they should list in their grant request, and setting up whatever they do get if the grant is approved.

Are any of you willing and able to help me to help them?

Thanks!
--Rob, W3RB

[K7JEM]

I could certainly give you some direction and advice. You need to determine what you actually need, and what of that stuff you want to keep. A simple repeater consists of the repeater, duplexer, feedline, and antenna. The choice for each of those items will depend on specific usage and amount of money to be spent. A pair of mobile radios will work as a repeater, but there are some disadvantages, such as the duty cycle thing.

Joe

[W3RB]

The duplexer, feedline and antenna all seem to be fine and suitable for the job. It would appear they just need something robust enough for regular, continued use, unless you feel there's a need to replace the duplexer, feedline and antenna.







In addition to questions about the repeater, itself, what about the shack? It does have a dehumidifier inside of it, but really is not very well ventilated, and things get very hot and humid here, in the tropics. They are already thinking of ways of cooling it better, but still protecting it from the elements. My main contact there has even thought that they could possibly run a loop of a line over from a nearby water tower/tank that would provide a natural, passive means of "water cooling" the shack. He is also considering a couple of other trees for shade, as well as changing the roof of the shack for better ventilation. What would you suggest, and are there other ideas we may not have considered yet?

Thanks again!

[K7JEM]

If the duplexer, etc, seem OK, then you might just want to replace the repeater. Do you need the interconnect? If not, a repeater like a Kenwood TKR-750 would be a good choice.

What is the temp inside the building? Can you put on an exhaust fan? Most repeaters will probably work OK up to 120 degrees or so without additional cooling.

Joe

[W3RB]

There's already an interconnect there - a CSI CS-800.

According to my contact there, when the repeater HAD been working, originally, people at the hospital, using walkie talkies to hit the repeater, used to be able to talk with people in San Pedro Sula, which is almost 120 miles away. To me, that sounds quite good, considering the jury-rigged setup they had been using. What would be the proper equipment they should have to be able to achieve that same level of communication without exceeding its duty cycle? Will the existing antenna, duplexer and interconnect be usable, or will everything have to be replaced? Would that Kenwood that you mentioned still be a good fit? What would be the approximate cost of everything that is needed?

As far as ventilation goes, I'm not sure of the internal temperature, but the temperature around here in the Summer is usually somewhere in the 90s, with lots of humidity. Also, to give you some idea, here is the view from the front door of their house:



That darker patch of blue you can see in the background is the Caribbean Sea, so in addition to the heat and humidity, there's also salt air. In addition to the other things I mentioned earlier, he has mentioned wanting to install an exhaust fan. Right now, with the sun beating on the shack, and the equipment operating, I'm sure the temperature in there must get pretty high at times.

[K7JEM]

There's already an interconnect there - a CSI CS-800.

If you get a new repeater, that would have to be wired in and levels set up. If you didn't need it, that would save some hassle. The repeater itself could be "plug and play", assuming the duplexer and antenna system are still in good shape.

According to my contact there, when the repeater HAD been working, originally, people at the hospital, using walkie talkies to hit the repeater, used to be able to talk with people in San Pedro Sula, which is almost 120 miles away. To me, that sounds quite good, considering the jury-rigged setup they had been using.

The range on the system will depend on the antenna. If there is nothing wrong there, then the range should be identical to whatever it was originally.

What would be the proper equipment they should have to be able to achieve that same level of communication without exceeding its duty cycle? Will the existing antenna, duplexer and interconnect be usable, or will everything have to be replaced? Would that Kenwood that you mentioned still be a good fit? What would be the approximate cost of everything that is needed?

If the duplexer, antenna, and feedline are all OK, all you really need is a repeater and power supply. The Kenwoods are very good, our club here has nine of them in current operation. They run 25 watts continuous duty. Sometimes ours are keyed up for 2 or 3 hours continuous, and we have no problem. The Kenwood repeater lists for about $1600, you might be able to get a "friendly" dealer to get you one at closer to $1000, that's about dealer cost. It would need to be programmed and aligned, but that is not a huge job. A power supply to run it can be any sort of decent unit, like an Astron RS20 or whatever. The radio will only draw about 8 amps in TX.

As far as ventilation goes, I'm not sure of the internal temperature, but the temperature around here in the Summer is usually somewhere in the 90s, with lots of humidity.

That darker patch of blue you can see in the background is the Caribbean Sea, so in addition to the heat and humidity, there's also salt air. In addition to the other things I mentioned earlier, he has mentioned wanting to install an exhaust fan. Right now, with the sun beating on the shack, and the equipment operating, I'm sure the temperature in there must get pretty high at times.

I don't know if there are any ill effects from salt air on the equipment. I have always lived in AZ, so not familiar with that sort of thing, but obviously these repeaters are shipped all over the world.

Joe

[W3RB]

Sounds good. I'll have to check the capacity of the existing power supply.

When you say "programmed and aligned," just what would that entail? Remember: I have NO experience with installing a repeater, and we can't exactly expect the dealer to fly down here to Honduras.

Also, do you happen to know of any of what you called "friendly" dealers? I'll check around, but it would help to know where to start.

Thanks!

[K7JEM]

Sounds good. I'll have to check the capacity of the existing power supply.

When you say "programmed and aligned," just what would that entail? Remember: I have NO experience with installing a repeater, and we can't exactly expect the dealer to fly down here to Honduras.

Also, do you happen to know of any of what you called "friendly" dealers? I'll check around, but it would help to know where to start.

Thanks!

Programming consists of setting the TX and RX frequencies and PL tones, hang timer, TOT, etc, via a software program. Takes just a few minutes, not unlike using a ham program to set up a mobile radio.

Alignment consists of setting TX power to where you want it, making sure repeat audio levels are correct, and aligning the RX front end. This process takes a little longer, but typically about half an hour.

Once these things are done, the radio could be shipped anywhere for install. That consists of mounting the repeater, attaching power supply, and attaching TX and RX coax to duplexer.



Joe