fm tansmitter site – Page 3 – Engineering Radio

WMHT’s former analog transmitter

During the digital TV conversion in the US, all broadcast television stations installed new transmitting equipment and antennas. Most stations ended up on a different frequency than their original analog channel. In Albany, New York, all of the TV stations moved to a common transmitter site and installed their antennas on a single tower.

Albany DTV tower, home of WRGB, WTEN, WNYT, WXXA, WMHT, and WCWN

For more on the Albany DTV site, check out the NECRAT page: www.necrat.us/albdtv.html

So, what happened to the old Analog TV sites in Albany?

For the most part, after the analog turn-off on June 12, 2009, the sites have sat empty. Such is the case with the former WMHT site.

Sign outside of former WMHT transmitter building

This old sign about sums up the end of analog television.

Former WMHT analog transmitter wide shot

The former transmitter operator desk. The maintenance log is still open. From the looks of things, they opened the circuit breakers and walked away. Everything remains intact from the antenna to the klystrons and exciters. It does appear that the coolant has been drained from the system. Other than that, it seems like the whole thing could be restarted with minimal effort.

Former WMHT Onan DFN 350 backup generator

There were two Onan DFN 350 backup generators. With a TV transmitter, running the cooling system after shutdown is vital. The idea here is that both generators in parallel could run the whole station, if one generator failed, then the cooling system would still run and cool the klystrons.

Former WMHT tower, wave guide and WVCR antenna — Former WMHT tower, waveguide and WVCR antenna

The former WMHT tower, which currently holds the WVCR-FM, WXL-34 (NOAA weather radio), and W44CT-D (Three Angles Broadcasting) Low power TV transmitter.

Current site occupants; WVCR-FM and W44CT-D

These equipment racks and the NOAA weather radio transmitter in the other room are the only active equipment at this site.

WMHT-TV Chanel 17 (488-494 MHz) was signed on 1962 from this site. The Comark transmitter was installed in 1984. The station’s analog ERP was 2000 KW visual, 200 KW aural.

It is an interesting site.

Decomissioning a NEXTEL site

Remember when “NEXTEL (b-b-b-beep), how business gets done…” Well, not anymore. NEXTEL was purchased by Sprint in 2005 and their product lines were combined. Thus, all of these old NEXTEL sites have become redundant and switched off. This particular site was co-located with one of our FM radio clients, which required a power reduction while the old equipment was removed from the tower. I took the time to grab a few pictures of the process:

Former NEXTEL communications equipment room

All of the equipment was removed from the equipment shelter. This site has been switched off since June 2013 and everything in it is destined for the scrap yard. This equipment worked on the 800 MHz bands, which have been re-purposed for Public Safety and Critical Infrastructure, e.g. government users. These racks and radios look like they were expensive:

Speaking of expensive, this site had over 4,500 feet (1,370 meters) of 1 5/8 inch foam coax, which was cut up and scrapped. At today’s prices, that cost $13.25 per foot.

The tower was rigged:

Each of the three panel sector mounts were removed and lowered to the ground.

The NEXTEL antennas were mounted at the 260-foot (80 meter) level of a 395-foot (120 meter) tower. It took some time to remove all of the antennas and equipment from the tower.

Cellular panel antenna array being removed from a tower

I looked on the Sprint website and could not determine if they still offer a push to talk service option (direct talk). With all of the communications options available today, I do not expect there would be much call for it.

For old times sake, here is an old NEXTEL commercial from many years ago:

They did have a good marketing department…

The PIROD PRLC-A tower lighting controller

PIROD tower company has been around for a while, thus there are likely many of these tower light controllers out in the field. They perform a vital service in controlling and monitoring tower lights at remote transmitter sites maintaining a safe operating environment for aircraft and compliance with FCC rules.

PIROD was sold to Valmont in 2004, Valmont no longer manufactures or supports the product. All is not lost, however, as XCEL Tower Controls does support it and parts are still available through them.

These units were fairly rugged, had good surge suppression on the incoming AC lines and are designed for easy access to service parts.

PIROD PRLCA tower light controller, WRKI Brookfield, CT

This particular controller is being installed at WRKI in Brookfield, CT. We are adding toroid cores to the tower lighting circuits coming off of the tower because the last controller has been mostly destroyed by lightning. It is a tall tower, on top of a tall hill, thus it gets struck by lightning many times over the course of a year.

The block diagram looks like this:

Click for higher resolution.

The basic schematic looks like this:

Click for higher resolution.

The entire manual can be found here, (medium sized .pdf) courtesy of John Brickley of EXEL tower controllers.