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.
Mount Mansfield TV and FM antennas
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.
Somebody working to preserve a record of past work:
Some of these have familiar looking cabinets and tube arrangements. They all look like classics to me and it is good that they are being saved. I noticed at the end of the video there is a Harris MW10A. As for the RCA Ampliphase transmitters; I maintained a BTA5J in Harrisburg PA on 580 KHz. It was reliable enough, but I could never keep it sounding good for more than a couple of days.
In any case, a worthwhile effort. More information at: AWA Transmitters.
I found this small, yet very important detail on a DB-37 connector attached to the back of a Nautel V-1 transmitter:
DB-37 connector for Nautel V-1 transmitter
The black wire is the ground wire and the orange wire is the remote RF off command. A closer view:
DB 37 connector from Nautel V-1 transmitter
The transmitter had been shutting down unexpectedly since it was installed. When these shutdowns occurred, there was no overload, no fault, no power interruption or other indication of a problem. When the RF on command was issued, the transmitter would turn back on and run with normal readings until it shut down again. It was a bit of a mystery; the transmitter was removed from its mountain top home and hauled back to the shop to be repaired. It was connected to all sorts of test equipment and studied intently for many days. Still, the problem could not be replicated in the shop.
Then the transmitter was hauled back to its mountain top transmitter site and re-installed. It ran well for about a month and then started going off again. This time somebody looked at the event log and noticed that a “Remote RF off command” was being issued at the same time the transmitter would shut down. Ahhh, the missing bit of critical data. That prompted me to take apart the DB-37 connector used for the remote control interface. The problem was obvious as soon as I removed the hood.
Sometimes the most valuable piece of test gear is the venerable Mk I, Mod 0, EYEBALL.
I unsoldered the ground lead and put some heat shrink over the connection to the DB-37. Hopefully, that will take care of it.
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 were 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.
WBPM transmitter room flood
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.
Top of WBPM QEI FMQ-3500 transmitter
The 1 5/8 coax switch was also damaged:
WBPM 1 5/8 coax switch
As was the remote control in the equipment rack:
WBPM Gentner remote control
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.
WBPM Saugerties, NY Nautel V-7.5 transmitter
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 a Bell Telephone System building.
