Here lately the Broken Arrow Amateur Radio Club has been doing some work on their 145.450 repeater located in the Bixby/Leonard area. In addition TARCs 443.850 repeater was just repaired today after a few weeks of low audio.
Also, in the recent past, RCWA's repeater got hit by a surge or a lightning strike and was off the air completely. As an interim solution, ww5wow Larry, used a repeater set up he had that would receive your signal and then re-transmit it on the same frequency. Your transmission would be stored in memory and then re-transmitted. You would hear, along with everyone else, what you just said. And this would all occur in simplex mode. The repeater would be listening and repeating on the same frequency. It made for slower transmission rates, but it did accomplish the goal of boosting a signal beyond it's limits (in most cases).
As an extension of that repeater work going on in the Tulsa area, we will be talking about repeaters here on the Tech Net tonight.
kb5vdb, Ron, sent in this explanation of repeaters:
A ham radio repeater is basically a radio system that receives the weak signal from mobile and portable radios, and re-transmits the signal on a different frequency at a much higher power level. Repeaters are usually mounted on TV and Radio broadcast towers, tall buildings, high hills, or mountains to extend the range of the station as far as possible.
The basic components of a repeater are the receiver, the transmitter, the controller, the power supply, the feed-line, the antenna or antennas (whichever applies), possibly a power amplifier, and a duplexer (cans) if one antenna is used.
There are two ways to construct a repeater:
1. Mount a single antenna as high as possible, and use it to both transmit and receive. Feed it with a single feed-line after running the signal through the duplexer. The big problem with this design is:
a. The cans are expensive, ornery, and delicate.
b. They have to be properly tuned, which requires a lot of EXPENSIVE equipment and a very knowledgeable technician.
c. They have a tendency to drift and become un-tuned.
d. They cause a lot of signal loss. (You also have to figure in feed-line loss for long runs.)
2. Mount separate transmit, and receive antennas as high as possible, separating the antennas by at least 100 feet. The big problem is expense of two antennas, two feed-lines, and of course, having to place the antennas at different levels on the antenna support. The big plus is no cans (and subsequently no loss through the cans) and if the repeater operator can locate the repeater box as close as possible to the antennas, you get most of your signal out.
There is a little delay every time that you key up, with some delays being substantial. Always allow a second or two before you start to talk.
The controller, by the way, allows a radio to become a repeater by allowing the transmitter and receiver to both operate at the same time.
ac5jm, Jerry, checked in and mentioned that there are a lot of variations to repeater set-ups but that Ron's explanation was a good summary. The on-frequency repeater, ww5wow's, is especially good for an emergency or disaster situation. It also might have an application on 10-meters since there is only 100 khz bandwidth, but nearly impossible to do without a dual site antenna. It's a good back up to have stashed away in case you need it.
The low audio problem on the 443.850 machine was a level problem. The site owner changed the temperature in the equipment room which allowed the pots to go out of tune.
ae5ft, Gene, asked. "Regarding the cans that have to be tuned: How does that fit in with repeater operation?"
k6jxy, Paul, answered, "The cavities keep the transmitter from getting into the receiver. They operate as a set. They are usually a six-pack on a set."
ke5okt, Jim, said, "I still have a KendeComm repeater that I'd like to get running on VHF. If anyone has any information on this brand or type of repeater, please e-mail me at jim@mounds.org.
ae5mn, Hank, asked, "Is there circuitry that separates the signal by detection of signal direction?"
ac5jm, Jerry, answered, "The receive side of the duplexer filters out the transmit and vice versa. The cans are manufactured for a specific range of frequencies and have to be tuned to be resonant to the frequencies used.
ke5zcz, Mike, asked. "Which repeater is better to have, one antenna/duplexer or two antennas, for a base repeater and what is the price range?"
kb5vdb, Ron, answered, "If you have a tower tall enough to separate the antenna by about 100 ft. and can get the radio close enough, you don't have the duplexers and the problems associated with them. If you don't have a taller tower, it's best to go with a duplexer. As far as costs... in the neighborhood of $5000.
ke5vas, Tim, asked, "Are there other linked repeater systems that cover as wide of an area as this one? How is the care and maintenance of the other repeaters handled?
kb5vdb, Ron, answered, "Maintenance is taken care of by the areas clubs, volunteers, and whatever funds they can raise. There was a linked system called Buffalo. It's not around anymore.
ac5jm, Jerry, added, "There are a lot of different clubs that have joined because of the affiliation with the National Weather System. The linked system is laid out to support the NWS. Ther are a few exceptions to this: Stillwater, Edmond, and Ponca City.
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