Paul Thurst – Page 45 – Engineering Radio

Failure to do Maintenance=Failure to have Tower

This is a tower behind one of our FM transmitter sites. In the past, it has housed paging and two-way services. It has always been sort of a slum, in my opinion. Several times, malfunctioning or improperly installed 900 MHz paging radios from this site have caused interference with our 950 MHz STL receivers. In recent years, all those things have gone away, however, to be replaced by a Wireless Internet Service Provider (WISP). Even with this change, the site is mostly overgrown and uncared for.

Yesterday, I noticed the tower was not as tall as it used to be, so I walked down the hill and saw this:

Self supporting tower after loosing top section — Self-supporting tower after losing top section

It appears this happened a few weeks ago. View from the other side:

Self supporting tower section resting on roof of building — Self-supporting tower section resting on the roof of the building

Close-up of the tower section that failed:

Looks like the bolts that held one of the flanges together failed, the tower was pushed over by a strong NE wind causing the other two legs to fail. Truth be told, the tower had been in rough shape since the mid-’90s. I am surprised that it stayed up this long.

WISP sector antennas. I don’t know if they owned the tower or were tenants. Either way, this is going to cost a few rubles to repair.

Looks like the shelter took a little bit of damage too. To be honest with you, I hope that this is it for this site. It would be nice if they take down the stump, scrap the lot of it and move it somewhere else.

Upgrading the firmware

The original V series Nautel transmitters have required a couple of firmware upgrades in some cases.

Upgrading the power module firmware, WDVT, Rutland, VT — Upgrading the PA module firmware on Nautel V-5D transmitter, WDVT, Rutland, VT

The first was for the controller to add a little bit of bias to the PAs during analog operation. The second one I have had to do is to the PA modules themselves which were to keep the power supplies from shutting off during re-transfer from Generator power to commercial power.

I have done several of these and once you get the hang of it, it only takes a few minutes to complete. Still, I remember when transmitters didn’t have firmware. The low voltage control circuits were either 120 or 240 VAC with big relays and contactors that loudly confirmed their closure before any meters began to move.

Regarding Nautel transmitters in general; the newer models are not the same rugged, reliable designs that were common in the past. We have AM ND series transmitters that have been on the air for 20 years without a single failure. The models rolling out of the factory these days often have switching power supplies fail without reason or warning and RF pallets that are fragile things. Ah well, I suppose all things are cyclical.

Out with the old, in with the new

Pictures of a backup power systems replacement evolution at one of our clients. The old generator was a Katolight 45FGH4, circa 1990. The new generator is a Cummins Power GGHE-1503557 60 KW 3 phase. Unfortunately, when the Katolight generator was moved from the previous studio location in 1998, it was never installed correctly. The 500-gallon propane tank was undersized, the gas tubing was undersized, etc. We fixed those items, but the damage was done. After running too lean under load a few times, the head gasket blew and there is oil in the antifreeze and antifreeze in the oil. It is a Ford straight-six engine, and sure, we could rebuild it, but why bother? This is a major group of stations in a very lucrative market, it makes much more sense to replace the entire unit.

Katolight Genset hooked up to the crane, ready to move

In addition to the head gasket problem, the load on the generator has increased. Since the old generator was installed in 1998, two more stations have been added to this facility. That means another air studio, another production studio, more computers, servers, air conditioning, etc. Thus, the new generator is rated for 60 KW.

After the GENSET is placed, connections for remote start, battery charger, block heater, and AC power output are made. We were able to reuse the existing conduit and cable, thankfully the electricians used 3/0 AWG cable for the AC power connections to the transfer switch.

It appears that they have dropped the Onan name, but not the color, completely.

The General Electric BY-4-C FM broadcast antenna

Whilst working in the generator room at WFLY, I found this bit of treasure stashed on an overhead shelf:

General Electric BY-4-C FM broadcast antenna, ca 1948 — General Electric BY-4-C FM circular broadcast antenna, ca 1948

That is a very old FM broadcast antenna from 1947-48. It must have been intended as a spare antenna in case the main antenna had a problem. It was never needed, so it remains in its original shipping crate. I would think that these were rather well made since the original main antenna was in service from 1948 until 1970 or so when it was replaced with a Shively 6710.

The entire antenna is intact including the Interbay lines, power divider T’s, and tuning section. Of course, it is of little use to the radio station today, as it is horizontally polarized. Perhaps some museum somewhere? I don’t know, it would be kind of neat to put it all together and use it as an exhibit.