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Grizzly Peak Trunked Radio System


 It was a typical summer day in San Francisco, California during 1991 when we were working on the installation of a new 10 channel trunked radio system at Grizzly Peak, a tower site that is located in the Oakland Hills above the east bay.  In an area of the country like San Francisco where the land has multiple mountain ranges, most radio systems are located at the high point of mountain ranges to get reliable radio communications since radio signals travel primarily line-of-sight.  Grizzly Peak being located in the Oakland Hills provides coverage into the SF Bay area including areas east of the Oakland Hills such as Concord.  The site had a telephone pole (which burned down in the Oakland Hills fire over 20 years ago) that was 140’ tall and a building at the base of the telephone pole which was built to house two-way radio and paging transmitters.  The telephone pole was like no other pole that I have seen.  Aside from the fact that it was heavily guyed, the phone pole was huge, being larger in diameter than almost any other telephone pole I had ever seen.  In addition, the pole was not one single pole, but two poles with one staked on top of the other with a 10’ tall steel splice sleeve.  This presented unique problems when attempting to mount antennas on the structure.

We left the hotel and started driving to the site.  We stopped at the local drive-thru restaurant to get something to eat.  I drove through the drive-thru with my vehicle which was a Chevy Blazer.  Richard was driving a bobtail truck which contained all of the repeater equipment that was being installed during this trip to the Bay Area.  Each site contained 3 racks of equipment and we were installing 9 sites in the Bay Area which meant that we had 27 racks of equipment in the truck when we started the project.  We had already installed two other sites, so we were down to 21 racks of equipment in the truck as well as a 6 foot diameter spool of 7/8” hardline antenna cable that was being used at each site.  We arrived at the site early in the morning around 7AM and proceeded to inspect the building and phone pole for the installation.  We worked with the site owner representative Dave to determine where we were going to install the repeater equipment and where we were going to locate the antennas.  At that point, Dave left the site to let us do our work.

We started the installation by identifying the specific racks of equipment that were needed for this site.  We had to remove the equipment from the truck and haul the equipment into the building.  This took at least an hour to get all the equipment into the building.  We then proceeded to secure the equipment racks to the floor, to the wall and to the ceiling so that the equipment would be secure in case of an earthquake.  (Since we all know that earthquakes do not occur in San Francisco, it seemed like a waste of time – Ha Ha)  A rotohammer was used to drill the concrete floor and place anchors in the concrete to hold the rack feet in place.  The top of the racks were secured with some cable tray to the wall giving proper stability to the racks so that they would survive a significant quake.

Now that the racks were secure, we could install the balance of the equipment in the racks.  (In order for the racks to be light enough for us to handle, the heavy pieces of equipment had to be removed from the rack and transported separately.)  We identified the equipment that belonged to this installation and carried it into the building where we proceeded to install the equipment in the racks.  There was a huge amount of cabling that needed to be installed.  The process of running the cables and connecting them in the proper place was a long and tedious task.  We wanted the installation to look good, so we used cable ties to secure the cables in place.  We had several systems of cables within the site equipment.  First we wired up the individual repeaters with their cables.  Next we wired up the data bus cables that connected the repeaters together.  Next we wired up the T-RIC bus for reporting telephone calls made by the radio users.  Then we wired up the T-LAN bus which was used to operate several items such as the power monitoring system and connect the TNT-100 logic decks together and the CR-355 call routers.  Wiring of the 12 volt power distribution was also needed along with wiring the master receiver signal distribution system and wiring up the transmitter combiner system.  All these things take time and we not only wired the cables, but marked them so that others that would follow us would be able to easily see what we had done thus making it easy for performing maintenance in the future.  Eventually, we had all the cables attached to the system.

Now we were ready to apply power to the system.  A power distribution bus was built by us and installed on the back of the racks.  We plugged in the repeaters into the power distribution and wired the power distribution to the power panel in the building, so we had our own power circuit and it would be reliable.  We turned on the equipment and started the preliminary checks.  We went through the equipment step by step to verify proper operation of the system and eventually decided that we were in good shape and that the system was functioning correctly.  We now had to connect the phone lines to the termination block and verified that the phone lines worked.  We also had to test the dial up modem that was used to control the system.

It was a good day’s work at the site.  We had accomplished what we had planned to do for the day and evening as it was now 8PM.  We cleaned up our mess, packed up our tools and proceeded to drive down the mountain, have dinner and return to the hotel where we would pass out from exhaustion.

The next day we got up a 5AM and proceeded to get ready to leave the hotel.  I drove through the local drive-thru otherwise known as the local choke and puke while Richard parked his truck in the remote section of the parking lot because you cannot drive a bobtail truck through the drive-thru.  We ate breakfast and proceeded to the site and arrived at 7AM.  Today was to be a difficult day as I was going up the phone poles to mount the antennas and run the cables.  So I donned the tower belt (long before today’s climbing harness), grabbed the rope and some tools and proceeded to climb the pole to the 80 foot level which was the crossarm just above he splice sleeve.  Since this pole was so large in diameter, it was difficult for me to reach the climbing steps on the pole.  Typically, the steps on the right side of the pole are about 36” apart and the same for the left side of the pole.  Therefore, each step makes one climb about 18” which is considerably greater than steps on a ladder.  In addition, the steps are on opposite sides of a very large diameter pole which makes the stretch from one step to the next to be greater than my ability to flex my legs even though this was done 29 years ago when I was younger, lighter, stronger and more flexible than I am now.  It was a challenge to get from one step to the next, because climbing phone poles was not something that I did more than once every 5 years.  This allowed me to find muscles that I forgot that I had for which I will pay dearly the next day.

So I started climbing the pole around 7:30AM and struggled to get to the next climbing step.  This continued for the first 30 feet until I had to rest.  After a few minutes of resting, I continued to struggle my way up the phone pole to the 50 foot level.  As I climbed up the pole, the diameter of the pole got smaller, making it possible for me to actually reach from one step to the next with my feet without having to jump from one step to the next.  This made it easier to climb and added quite a bit of safety.  After resting at the 50’ level, I continued up to the 65’ level which was easier to do as the pole continued to get smaller in diameter.  However, once I got to the 65’ level, I was faced with climbing up the splice sleeve which was thick steel.  There were some climbing pegs on the splice sleeve, but two of the climbing pegs were missing.  There was a “nut” welded to the splice sleeve that normally would have the pole step screwed into the nut which provided something rather than nothing to grab and step on, but it was far from ideal.  Climbing down and getting a pole step to screw into the nut welded onto the splice sleeve was not an option as we would have to leave the site and we would lose the day for work, so I continued up the pole taking extreme care with every move I made in an attempt to scale the splice sleeve.  After much delay, consternation, fear and determination, I managed to get past the splice sleeve and was back on the wooden part of the pole.  Now I had to climb about another 5 feet to get to the crossarm where we planned to mount the antennas.

Once I arrived at the crossarm at the 80’ level, I had to rest for 10 minutes before we could start any activity.  I had dragged the rope up the pole as I climbed and now I used the rope to get a pulley sent up to me along with a bottle of water.  I hung the pulley above the crossarm on one of the climbing steps and put the rope through the pulley.  Now we were ready to start the process of mounting the antennas.  The crossarm was not set up properly for mounting additional antennas, so some work was required on the crossarms to drill holes in the horizontal angle iron members and mount two mounting pipes so that I could mount the two triple omni-directional antennas.  (Each antenna was about 15’ long and weighed about 55 pounds and each of the two antennas contained 3 separate antennas internally.)  The system required the use of 6 antennas; one for all the receivers which were all fed from the one antenna and 5 transmit antennas with two transmitters being combined into one antenna using 2 channel hybrid combiners which is used for close frequency spacing.  Since the 900MHz channel assignments from the FCC were all adjacent channels, we could not use regular low loss combining.  This was the best compromise for an antenna design in terms of cost, performance and physical antenna space requirements on the antenna structure.

I went to work building the mounting for the antennas on the crossarm.  This required the use of power tools including metal saws, drills, U-bolts and a lot of time.  Eventually, I had the mounting brackets built for the antennas and then proceeded to have Richard send up the antennas mounting brackets to me along with another water bottle.  I installed the brackets and got them ready to hold the antennas.  Then Richard sent up one antenna at a time for me to mount.  After securing the antennas on the crossarm, it was time to send up the flexible jumper cables that connect the antenna to the 7/8” hardline antenna cable that still needed to be installed.  The hardline cable is very stiff and connecting the cable directly to the antenna generally does not work, especially with this antenna that had 3 connections on the bottom of each antenna that are too close for such a large cable.  Also the connections will break if connected directly due to the constant flexing of the antenna structure.  I got the flexible jumper cables and installed them on the bottom of the antennas.  I then used the heat gun to shrink the Heatshrink tubing that seals the connections and makes them waterproof.

Now it was the time to start installing the antenna cables.  Richard and I had set up the cable spool before I climbed the pole.  Now, Richard attached the cable to the rope and we pulled the cable up the pole with another water bottle.  Once I had the cable at the crossarm, I attached the cable to the pole so that Richard could get a measurement on the cable to be able to cut it long enough to get inside the building and connect to our radio equipment inside the shelter.  In addition, we had to mark each cable with a color code so that we knew which cable went to each antenna which we would need to know when we were hooking up the antenna cables to the radio system.  (The cable is about $4 per foot, so it is best not to waste a lot of cable.  However, cutting the cable too short is also a huge problem so we had to be diligent about measuring how much cable we needed.)  Once the cable was cut, Richard would install the next connector and send the cable up the pole after attaching it to the lifting rope.  This process went on for all 6 runs of cable until we had all of the cables up the pole.

Now it was time to do the final connections up on the pole.  I had the Heatshrink tubing and the heat gun.  I placed a sufficient amount of Heatshrink on the cable to be certain of covering up the connectors and making certain that the cable is sealed and waterproof.  This process takes quite some time when working under the adverse conditions that were present on the pole.  After shrinking the Heatshrink tubing and being certain that everything was properly sealed, it was time to start climbing down the pole.

Climbing down the pole was quite a challenge, a lot of work, dangerous and I had to secure the cable to the pole as I climbed down.  This required me to install clamps on the cables every 3-4 feet while climbing down the pole.  This was very challenging while trying to climb down past the splice sleeve.  There was no good way to secure the cables to the metal sleeve, so I bundled all the cables together with other cables already existing on the pole which made a rather rigid bundle of cables.  I continued doing my work as I slowly climbed down the pole.  Eventually, I finished and got to the bottom of the pole.

Eventually, I got back to the ground and it was now 8PM in the evening.  I had been on the pole since about 7:30AM, so I spent 12.5 hours straight on the pole without a break.  We packed up our tools, cleaned up our mess and proceeded to head down the mountain, get some dinner and head to the hotel to pass out again.

The next day was our final day at Grizzly Peak.  We repeated the same schedule as the other two days and arrived at the site around 7AM.  Now it was time to work on bringing the cables that we installed the day before into the building, secure the cables, route the cables over to our equipment, terminate the cables with the proper connectors and then install the jumper cables from the hardline cables to our equipment.  Each antenna was tested in sequence to make certain that the antennas were radiating the signal and not providing a bad match.  Everything tested out OK and we were pleased with the results of the installation.  We finished handling some other details of the installation including sealing the building where the antenna cables entered the building.  We performed the final cleanup of our work, collected the trash, loaded our vehicles and left the site knowing that we had done the best job that could have been done under the circumstances.  However, the proof was in the pudding and testing the coverage of the system was next.  After driving around testing the radio signal quality, we pronounced it a total success.  This job was done for Fleetcall which was the predecessor to NEXTEL and their personnel agreed that it was a complete success and well done.

All in a days work……………..

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