Mount Bigelow

Mt. Bigelow is the hub of CARBA’s microwave linking project. Located east of Mt. Lemmon, Mt. Bigelow is situated such that there are many line-of-sight paths available. As our system grew, our site on Mt. Bigelow matured. As we changed, so did the building. We were originally located in the attic of the television transmitter building. With the advent of digital TV, the building was expanded and our little attic space became a full blown floor with 3 dtv transmitters next to us.

 

In the photo above three of our grid dishes are visible, the one on the far left points to downtown, the center one points toward Elephant Head and the one looking away is aimed at Heliograph Peak.

We now have some photos of the construction on the Mt. Bigelow site. These photos were made during the preparations of the site for the new Digital Television transmitters, now on the air. You can see how we relocated our dishes to make room for the construction.

 

Our original racks and microwave interface. Some of the dishes were mounted indoors.
The front of the new rack sports a SRS controller. Looking from the back, all the mux cross-connections are made via a panel of punch down blocks wired by N6DGT.
The antennas were mounted outdoors on the new ice shield superstructure of the building. Our Mt. Lemmon facing dish.

 

Pinal Dish Antenna Repair
We had lost our microwave signal to Pinal and after extensive testing by W7HSG, WA7ELN, KD7DR and N7TWW, it was determined that we had water in the feed of the dish antenna at Mt. Bigelow that points toward Pinal. This antenna is mounted on the building ice shield superstructure and sits a couple of stories off the ground. The dish hangs out over empty space, so it is almost impossible to get to it from the feed side of the antenna.

We called in the experts and got results: Thanks to Mykle and crew for an excellent job. The following is his report:

The antenna repair has been completed, with reports that the signal across the link is better than it ever has been.

The crew:            CARBA SARA
W7HSG  Ralph Turk        *
KD7QPA Bill Florence       *
N7MCK  Cathy Wasmann     * *
N7INN  George Simons     * *
KC7LAW James Hoiby         *
KF7QQF John Perchorowicz   *
N7JZT  Mykle Raymond     * *

Support in the background:
WA7ELN Troy Hall         *
N7CK   Mike Bucciarelli  *

The project, as always, found ways to extend the time required to get the job done. The culprit was the “S” hooks connecting the feed to each of the four guy wires connected to the rim of the dish. The feed was easily unbolted from the back of the dish (with a couple of people standing high on a ladder that was tied off, and the people were tied in with their harnesses). Pulling the feed out the back of the dish required unfastening each of the cables while working around the tip of the feed in the slightly larger hole in the dish. The “S” hooks are a heavy gauge wire. The crew prevailed.
Ralph disassembled the feed, finding several of the non-metallic screws had lost their heads (!). So the seal wasn’t very good, and a small amount of water was dumped out. Ralph was ready with replacement parts,and all went back together without drama, with good prelim RF behavior (just the feed, no dish).
Then it was back up the ladder, and more tedium while getting the cables attached and the orientation of the feed correct. The feedline and jumper had been checked with a dummy load, while we were at it. Final RF checks were good, and on-the-air reports had some people skeptical that a link was included. This antenna is part of the link from Bigelow to Pinal, so there are two microwave links between people talking on the Lemmon and Pinal remotes (repeaters).