This transmitter was retuned from 107.9 to 92.9 and put back into service. Retuning an HT35 transmitter is no small matter, there are 32 pages of retune instructions. This unit is now in service as the main transmitter for WEZF, Burlington, VT.
The transmitter power output is 22,000 watts into a four bay, three around panel antenna, which gives it an ERP of 46,000 Watts at a height of 824 meters (2,703 feet) above average terrain. The tower is at the summit of Mt. Mansfield, which is 1,340 meters (4,395 feet) above sea level.
This is the Mt. Mansfield FM transmitter room. There are two TV stations in this building as well.
Final frames are of the WVPS Nautel NV-40 transmitter.
Last year, the main antenna and transmission line for WSPK was replaced. I was, therefore, somewhat surprised to hear that there was an issue with the new transmission line. And yet, problems there are. Most likely, some ne’er do well has shot the transmission line with a bullet making a hole, which, when it rains, allows in water. Said water then accumulates in the bend at the bottom of the tower. When enough water is present to fill the gap between the center conductor and the outer conductor, this happens:
For those of you keeping score at home, that’s 980 watts forward, 375 watts reflected or about 4:1 VSWR. Obviously not a good load, in fact the transmitter shut down. Fortunately, the backup transmitter and antenna system worked flawlessly.
This began happening last month, usually after a heavy rain storm. Thus, I went out to the base of the tower and shook the transmission line and sure enough, water was sloshing around in there. Last time time it happened, a tower crew was summoned to inspect the line. Inspect it they did, but did they find any holes? No, they did not. Perhaps the issue is with the antenna itself, in which case the entire thing will have to be removed from the tower and lowered to the ground. In the mean time, my boss drilled a small “weep hole” at the bottom of the bend where the line comes off the tower.
I uncovered this weep hole and pressurized the line and viola, lots of water came out:
A bit unconventional, but effective nonetheless. The first video is of the water dripping out:
The second video is of me walking back into the transmitter building to pressurize the line:
Everything is very noisy because it is Monday, when all the generators on site exercise. There are five diesel generators running while I was videoing recording this.
I would estimate about 6 ounces of water came out through the weep hole, most of it landing on the ladder underneath. After the water was drained out, the transmitter came back on at full power and normal VSWR.
A temporary fix to get the station back on the air. The real repair work will begin when the antenna comes down to be inspected.
Update: The tower climbers did find a hole in the transmission line, just below the flange that connects to the antenna. It looks like a pencil sized gash just before the line bends back to the tower. Lightning? Rifle bullet? Damage while installing? We can’t really tell. They installed a patch over the hole which holds about 3 psi line pressure. We then used a vacuum pump to evacuate the line, then recharged with dry nitrogen.
Regarding Pedro’s question below in the comments: Since we found this problem quickly and were able to evacuate the line, there should not be any corrosion, that is our hope. Time will tell
The WKZE single bay antenna is mounted on the left hand tower.
The transmitter is a CCA FM3000DS, made new in April, 1970:
The CCA designs are dirt simple. Grounded grid, driven with an external solid state amplifier that is a modification.
As you can see, this transmitter was originally manufactured for WHVW-FM, which is now WCZX. The station has a large, mostly cult following throughout the mid Hudson valley. Even though it is a 3,000 watt class A station, it’s coverage carries far beyond it’s theoretical 60 dBu contour:
This incident happened a few years ago. I thought I had lost the pictures of the disaster, but I found them this morning on my thumb drive. Hooray! This occurred one morning just before Christmas after the area received a snow/ice/rain storm. The gutters on the old ATT long lines building clogged with ice and the water on the roof built up. Unfortunately, the transmitter was installed directly below a disused exhaust stack for the former backup generators.
I received the off air call from the morning show while I was driving to the office. I diverted and went to the transmitter site and found water pouring into the top of the main transmitter.
Thus, water ran down directly into the top of the QEI FMQ-3500 transmitter (transmitter was upgraded to 6 KW). Unfortunately, high voltage and dirty stack water do not mix. The combination of sooty, iron laden water and the B+ damaged much of the transmitter circuits beyond repair. The main transmitter is on the right, the backup transmitter is on the left.
I inspected the backup transmitter, also a QEI FMQ-3500, and it seemed to me that no water made it into the unit. I rigged the tarp to ensure that none did, which was a very pleasing bit of work, what with the cold, smelly, dirty diesel water dripping on my head and running down my neck and back.
The 1 5/8 coax switch was also damaged:
As was the remote control in the equipment rack:
Fortunately, the backup transmitter ran, although I pressed the plate on button with a dry wooden stick while standing on a dry, non-conducting ladder. Even so, I still felt a little trepidation holding that stick.
It took almost a year, but finally the insurance company for the building owner came through, and a new Nautel V-7.5 transmitter was installed. I believe this is the last V transmitter Nautel made. We moved the transmitter location across the room, not under the old generator stacks. We also removed the generator stacks and patched up the roof with hydraulic cement and roofing tar. By the way, that yellow color should look familiar to anyone who ever worked inside of a Bell Telephone System building.