It was a typical hot summer day in Orlando, Florida when we were working on the installation of a new 10 channel trunked radio system on the Starkey Road Tower. In an area of the country like Florida where the land is flat, towers and tall buildings are required to get reliable radio communications since they do not have tall mountains to get the antenna height. The Starkey Road Tower is located in the city of St Petersberg which is about 15 miles across the bay from Tampa, Florida.
The Starkey Road tower is about 640 feet tall and was built to house two-way radio, cellular and microwave systems which are located in the building at the base of the tower. It is located at 8320 Starkey Road, Seminole, Florida a major north-south road just north of the St. Petersburg area and provided significant coverage of the area. The tower is owned by Pinnacle Towers out of Cannonsburg, PA. The issue of using the site is the height of the tower and the length of the feedlines. The long feedline length requires the use of larger cables which increase the cost of the installation for both materials, labor and signal loss. Since every foot of cable loses a certain percentage of the signal, one must go to larger and far more expensive cables to utilize the site.
The system that I was installing was 10 channels which would require 11 antennas, one transmit antenna for each channel and one receive antenna for the system. This represented too great a cost for labor, materials and monthly rent to be on the tower. Therefore, I had to consider finding a way to minimize the antennas on the tower. I built a spreadsheet to look at the different scenarios of cost and performance which determined that we could get the best bang for buck if we used 4 antennas. Three of the antennas would be transmit with 3 channels per antenna. The 4th antenna would be the receive antenna and transmit for one channel. This required a custom antenna system design which was purchased from TxRx Systems.
The height of the tower required that we install a tower top amplifier system. This is because the long feedline introduces enough loss into the receive system that it will compromise the performance of the receivers. In anticipation of having a large number of portable radios, it was necessary to utilize a tower top amplifier system which would significantly increase the ability of the repeater system to hear the portable radios in weak signal areas.
We brought the equipment to the site in a truck from the radio shop. We unloaded the equipment, carried it into the building and proceeded to install the equipment. After two days of work, we had the entire system operating in the building, less the antennas, cables and the tower top amplifier on the tower. We tested all the channels, the telephone lines, the interconnect to make phone calls, the modem to program and control the system and every other aspect of the system. Now, we needed the tower crew to install the antenna system on the tower.
The next day, the tower riggers showed up to install the equipment on the tower. It took them some time to rig the tower for the installation. They then proceeded to mount the antennas and then started raising the feedlines up the tower. When pulling such large cables up the tower, one must use a cable and winch to raise the cables due to the weight and the cable must be supported every 150-200 feet to keep the weight of the cable from causing the cable to stretch and deform which ruins the cable. The cable has to be clamped to the tower every 5 feet from the top to the bottom, so this process takes a lot of time to complete. The tower crew consisted of 6 people and they continued to work all day attaching the cables to the tower and the antennas.
While the installation of the transmitter antennas and cables was progressing, we received the tower top receive system from the manufacturer. We assembled the tower top amplifier system on the floor of the building and plugged it in to test it. Delaying the tower crew is expensive, especially if we delay them enough that they need to spend another day on the tower. Therefore, it was imperative that we got the tower top amplifier unit ready to be installed on the tower and we had very little time to do it. It appeared to work, so we gave it to the tower crew to hoist up the tower since they were waiting for it.
The tower top amplifier went up the tower and was installed at the very top of the tower. When the feedline was connected, it worked. In fact, all the antennas and feedlines worked well and had a good antenna match which means that the antennas were operating efficiently. We were initially pleased with the system performance.
The next day, we went back to Starkey Road to finish all the testing of the site before moving on to another tower site. However, we were dismayed to find out that the tower top amplifier appeared to fail one of the tests. The system contains a backup amplifier in case lightning or some other condition causes the amplifier to fail. The control panel has the ability to switch from the main amplifier to the backup amplifier through a remote control panel that is part of the tower top system. The system also contains a secondary cable that allows testing of the amplifier system from the ground by feeding a test signal up the secondary cable up the tower to the tower top amplifier and then returning through the receive system at a predetermined level so that it is possible at any time to test the system without having to climb the tower. Although the basic tower top amplifier system functioned properly, the remote testing feature and the remote control system that would switch from the primary to the secondary backup amplifier was not functional. This gave us considerable concern that we could have a long term problem if we were unable to resolve the situation. So now we had to figure out how to fix the problem.
When we received the tower top system, we actually received two of them. The other one was to be installed on a different tower in St. Cloud which was also about 500 feet tall. We decided to hook up that receive system on the floor of the building and see if it worked correctly. This system appeared to work perfectly, passing every test that we threw at it including all of the remote test facilities. So we took the remote control panel that was to be installed inside the building and swapped it with the remote control panel that was installed at the site. Unfortunately, nothing changed with the tower top amplifier so it was clear that the problem was on top of the tower and not in the remote unit inside the building. That means we had to climb the tower to fix the problem as the tower crew was now long gone and not available. Climbing a 500’ tower is no insignificant task and none of us were in proper shape to do it. Randy was the only one who came close to being in shape to climb as he regularly worked on towers that were 150’ or less. He had never climbed 500’ up a tower which represented a significant challenge for him. I felt like we were trying to solve the problem with Apollo 13 that occurred back in the late 1960s when the capsule had a severe failure and now the job was to get the men home safely which was against the odds.
The next day was a clear and calm day to climb the tower. To aid in troubleshooting the system, we had the other tower top receive system completely assembled and functional on the floor of the building so that we could attempt to duplicate the problem during the troubleshooting process to verify that we actually found the problem. This is the same process used by NASA to duplicate, troubleshoot and determine a solution to problems with anything that is sent into space. They have a duplicate device on the ground that they can work on to try to simulate whatever difficulty is occurring and determine the solution to the problem.
We had to think of everything that he could possibly need to fix the trouble. We had only this one day to fix the problem without throwing our schedule into a tizzy. When you are 500’ in the air, you cannot talk to anyone on the ground, so radios were necessary to communicate with each other. Randy was an installer and not a radio technician, so his ability to troubleshoot problems was limited. I had the ability to troubleshoot the problem, but I was not capable of climbing that high up a tower. So I spent some time familiarizing Randy with the tower top amplifier, the components and how they were connected together and the terminology so that when I would ask him to do something, we would be capable of understanding my request and executing the command. We developed a system of referring to different components within the system so that I could talk him through the process of being my arms and legs to get the job done.
The time arrived for him to start the climb. It was about 9AM, so we were ahead of the main heat of the day. He had a rope in case we needed to send up something up to him. He had a volt-ohm meter to perform the tests that I needed him to do. He had two bottles of water for the long climb. Away he went up the tower. The first 100’ did not take him more than 5-7 minutes as he was accustomed to climbing that high. I cautioned him to slow down as we were running a marathon and not doing a sprint. I wanted him to reach the top of the tower alive and get back down without heat stroke or complete exhaustion. Aside from the fact that we did not need to have an OSHA incident, Randy was an employee and friend. I was truly concerned with his safety since he had never climbed that high before today. I told him to rest at 100’ before continuing to the next 100’, but he was anxious to proceed. There was not much I could do to stop him since I was on the ground and he was up on the tower, so he proceeded to the 200’ level. That took him about 12-14 minutes, about double the amount of time it took him to climb the first 100’ on the tower.
I insisted that he rest for at least 10 minutes before proceeding. This time, he was willing to listen to my demand. I think he took 12 minutes before proceeding. The next 100’ was even more challenging. Even though he stopped to rest, this process was exceeding his normal work endurance. Climbing 500’ towers is nothing to take lightly and normally requires quite some time to build up the stamina to be able to do. It easily took 20 minutes for Randy to climb the next section to the 300’ level. This is more of the pace that he should have taken on the lower portion of the tower. He rested for 10 minutes and proceeded to the 400’ level which took about 30 minutes. After another 10-15 minutes of rest, he climbed the last 100’ to the top of the tower which took another 30 minutes. It was time to rest for 10-15 minutes before proceeding with the troubleshooting operation.
Now it is time to find out what has gone wrong. The first thing that he had to do is to open up the NEMA4 cabinet that contained the receive system. NEMA4 cabinets are completely waterproof to protect the electronics inside the cabinet, so it takes a few minutes to unscrew all the clamps that keep the door closed and waterproof. Then the door is opened exposing the electronics.
I had Randy swap the amplifiers to verify that they both worked. I then had him measure the voltage on the amplifier that was sent up the cable from below which we determined was normal. Then we measured the voltage on the amplifier unit when the system was set to operate from the primary amplifier. The active amplifier had 12 volts and the secondary amplifier has 0 volts. This was an expected result. We then switched the unit to operate from the secondary amplifier and repeated the same tests. We found that there was 0 volts on both amplifiers. This told us that there was something wrong with the power switching circuit which was housed in a shielded assembly near the bottom of the tower top amplifier assembly. We tested the switching circuit that was used to switch between the amplifiers and it seemed to work, but when the secondary amplifier was switched in, there was no power on the amplifier. So we began the tedious task of determining why the voltage was not switching properly. Each wire that was connected to the switcher was a shielded cable using a shielded coaxial connector which made the measurement of voltages difficult because there was no exposed connection to which we could connect the probe. We traced the wires on each unit one at a time. There were 5 cables connected to the switcher, so we started on the left, calling it number 1 and proceeded through cable 5. I would call out a cable position on the switcher and follow the wire to its destination in the unit I had on the ground. Then Randy would do the same thing on his unit at the top of the tower so that we could verify that both were the same. The first cable was verified. We then proceeded to do the same thing on the second cable on the switcher, so we determined that both wires went to the same location. We then proceeded to cable 3 which I traced to an assembly in the unit. When Randy traced his unit, it went to a different assembly. Finally, it seemed like we were getting to the source of the trouble, but we still had more work to do before we knew what was actually the problem. I noted where Randy indicated his cable went in the unit, then proceeded with cable 4. Again, I traced the cable to a certain location in the unit and Randy traced his cable 4 to a different location. I recorded the position that he indicated. Finally, I traced cable 5 to its location in my unit and he traced his cable to the same location that was in my unit.
It appeared that 3 of the 5 cables matched and two did not match. Of the two that did not match, I looked to see where they went in the unit and it became apparent that the two cables were switched. I felt that I should reverse cables 3 and 4 on my unit to see what happened, so I proceeded to do so. After reversing the cables, my unit was now performing the same way as the unit on the tower. I then reversed the two cables again placing them back in their original position and now the unit performed properly. This gave me a high level of confidence that when I would tell Randy to reverse the two cables on his unit, the problem would be resolved.
I told Randy to reverse cable 3 and cable 4 on his unit. This took him a few minutes as he was in an awkward position and could not get to both of the connectors without repositioning himself. It took awhile but he finally switched the two cables that were reversed in the power switching circuit. After reversing the cables to match the unit on the floor, the tower top unit now worked, the secondary amplifier worked and the test cable system also worked. A complete success!
Now it was time to close up the NEMA4 cabinet and be certain that it was properly sealed against the weather. We did not want our hard work to be ruined with the weather via a bit of carelessness. After we were convinced that all the hatches were secure and that all connections were properly sealed, it was time to put all the tools and equipment into the bucket and lower the bucket and rope. This would make it easier on Randy during the long climb down the tower which would last about 50 minutes. Climbing down is easier than climbing up, but it is no insignificant task. Leg and arm cramps are common when expending that much effort when you are not accustomed to such a long climb. I told him to rest for at least 5 minutes every 100’ of his decent. He complied without any argument.
When he got down the tower, we both embraced each other. He was my hero, since he was able to do what I could not do and managed to allow me to be up on the tower remotely through him. We both celebrated our success and it was time for an ice cold beer. We do not normally drink on company time, but after such a long and difficult task, I felt that it was the right time to make an exception. After resting for 30 minutes and having 2 beers, Randy was ready to rejoin the human race.
And I was ready to give a big sigh of relief knowing that we had succeeded with an almost impossible task………………