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History of the Tesuque Peak Repeater
Article by Alan Hill, N5BGC

Let's look at a little history of our two meter radio system on Tesuque Peak. It was installed about 1972 by several local hams. The repeater was bought from the State of New Mexico by the club. It was a Motorola radio that was designed to be a repeater when it was built. This, of course, gave it an advantage since it did not have to be modified. A CW id was added to fulfill FCC requirements. There were no controls with the controller.

It was first installed in a Quonset hut at the south end of the mountain top. The state used this building to house the standby generator used for the state radio equipment. The coax ran to the top of a tower owned by Motorola for use by commercial entities on the peak. The tower was about 60 feet tall and we were right at the top. This provided us very good coverage at the time. Of course, there were only about 30-40 different transmitters on the mountain top.

A few years later, that tower was replaced with a new one and ownership changed. At that time, we lost our free use of the tower. So we decided to take the antenna and put it right outside the door on the Quonset hut building. It was at a height above ground of about 8 feet and, of course, there was only about 10 feet of feedline. The system worked well there but there were beginning to be dead spots in the coverage.

When the state rebuilt their site in about 1987, that building was removed and the radio was installed in the state building were we are now. We are very lucky in that there has been a Santa Fe ARC member working for the state Radio Communications group since the first repeater was installed. The state also installed a 60 foot self supported tower. We had to use what space that was available on the tower. At first we ended up on the south face. About this time, the population of radios on the site began increasing. It was about 100 by then.

At about this time, we replaced the Motorola radio with a commercial GE. It was called a Master. It had a transistorized receiver and transistorized exciter and a tube multiplier, driver and final. This radio was interfaced with a UHF radio that was used by the autopatch. The autopatch was located at AG5S Alden Oyer's house in Santa Fe. This arrangement worked when the State Police and Los Alamos Police department were not transmitting. These frequencies plus the second harmonic of our own transmitter were killing us. I will write up an article describing how that happened. It is not a major problem now.

About 3 years ago, the technical committee installed a CTCSS tone on the receiver to cut down on the constant intermodulation interference. This is very necessary for operation on the mountain top with in excess of 150 transmitters.

About 2 years ago, we moved the antenna to a slightly higher location on the northwest face of the tower. That location plus better mounting hardware allowed the antenna to work better.

About 3 years ago the club bought several GE mobile radios that were removed from commercial service. These radios are very close to the Master 2 repeaters that GE just a few years ago quit making for the two way industry. They are crystal controlled with 1 to 8 channel versions. The channels are derived simply by switching crystals. The technology was state of the art for the time period. Since they were removed from commercial service, the range for the frequency tuning on the front end is from 150.8 to 174 MHz. Since we have to retune the front end to 146.22 MHz, the "Q" of the tuning circuits is compromised. The radios will tune this far, but the quality is not there.

Of the 3 radios that we bought, all three of them experienced tuning problems. When the technical committee went to the site, we retuned the coils and capacitors and get the receiver back within specs. A few months later, the problem reoccurs and we have problems with getting a weak signal through the receiver front end.

The technical committee has another radio in place for the site. It also is a GE and this one has the correct front end. It covers from 132 to 150.8 MHz. That puts 148.22 MHz well within the designed bandpass. This is the repeater that is now in service. It works well except for a few minor problems that occur now and then.

Overall the 146.820 repeater has been in place for about 30 years with various electronics. We have done this without breaking the club budget. Do we need a new more modern repeater? It would sure be nice, but the $1000 price tag is not in the club budget. Fortunately, the technical committee enjoys going to the top of the mountain.

Alan Hill, N5BGC

 

 

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