Paul Thurst – Page 187 – Engineering Radio

General Electric BT-25-A

This is one of my favorite old transmitter memories. Back when I landed my first Chief job, I was working for an AM/FM combo. The AM station was a 50,000-watt flame thrower that first went on the air in 1947. The original transmitter, a General Electric BT-25-A was still in service as a backup unit. These pictures are from the last night it operated, December 16, 1993. The bank made us remove all of the PCB transformers and capacitors before they would refinance their loan. Of course that was most of the transmitter, the rest of it was scraped or sold for parts.

This is a long transmitter, GE BT-25-A looking from the control cabinet

The transmitter takes up the entire span of the room. There were eight large cabinets, each with its own stage or section. The stages were connected to each other by a wiring trough in the floor. The transmitter used lead-jacketed cable within and between sections.

IPA stage with "multi-meters" — IPA stage with “multi-meters”

The IPA section had been modified to use 833A tubes. This is where the RF was developed and amplified for the final section. It is in the middle cabinets of the transmitter, the audio and control section being to the left, the PA and PA power supply being to the right.

PA section. Those WL 5891 tubes. — PA section. Those are WL 5891 tubes.

Final section. There were three tubes, only two were in use at any given time. The third tube was a spare which could be quickly placed in service by throwing a knife switch and moving those bars on the back wall around. This picture was taken with filament voltage only, we had to close the door to turn on the PA voltage.

The transmitter was cooled by this blower which faces down into the floor. Concrete duct work carried the air to the various stages of the transmitter. The blower is powered by a 2 1/2 HP motor. There were two blowers, one in use and one in standby. Behind this is an air mixing room and filter room. During the winter time, the transmitter waste heat was used to heat the building by closing a series of ducts and opening other ones.

Modulation transformer and modulation reactor

This is in the transformer vault. The unit to the left is a modulation transformer, it was 7 feet tall. Directly in front is the modulation reactor and just out of the picture to the right is the plate transformers. The plate supply was 480 volts 3 phase. The other piece of green equipment is a hydraulic tube jack, to get the 5891 final and PA tubes out of their sockets.

The transformers were what contained most of the PCBs. The modulation transformer contained about 150 gallons of Pyranol, the GE trade name for their transformer oil. Pyranol contained greater than 750,000 parts per million PCB.

It is a shame we had to kill this transmitter, it sounded wonderful on the air. The day we signed it off, there was nothing like it, not the Mw-50B that replaced it, nor the Nautel ND-50 that replaced the MW-50, nor the DX-50 at the competing station across town.

What a shame.

WBCQ The Planet

File under: What I wish I could do, if I had the money.

Imagine, as an engineer, owning and running your very own radio station. Not just any radio station, but a 50,000-watt flame thrower heard over most of the eastern US. Dude! Only one minor detail, it is a Shortwave station, which, by FCC regulation is only supposed to be listened to outside of the US, hence the official FCC name, International Broadcasting. As I said, minor detail.

Anyway, WBCQ is heard at various times on 5110, 7415, 9330, and 15420 kHz both in and outside of the US. Their full schedule here. Last night I was treated to the Lost Discs radio show, featuring rare tracks not often found or heard anywhere. It sounded like they were having a lot of fun and it was entertaining, which is why I continued to listen for well over an hour. Besides this, they played a cover of one of my favorite songs, Wish you were here, as played by Kris McKay.

I put up the video for the song that was in it, and, no, I don’t know who those grainy people are.

It seems that the owner, Mr. Weiner is a fellow radio engineer and long-time radio enthusiast. He was and still is a strong proponent of radio for the good of the public. Most of his earlier attempts to own radio station fell on the other side of the legal line, being not quite sanctioned by any government authority. At first, he did attempt to obtain a license and was turned down by the FCC, prompting him to write this reply (shamelessly lifted from Wikipedia):

…we went about a year ago … to apply for a license. Our attempt proved quite humorous to your employees, who sent us away with word of “Forget it.” Further investigations showed us why our attempt was then so comical. Licenses were so expensive and hard to get that even small stations were being sold for millions. Broadcasting was reserved for power men.

…We are not disputing, however, your right to assign channels and set aside bands for the prevention of interference. We certainly, however, are disputing your right to reserve broadcasting for the well-to-do only.

So, I applaud Allan Weiner and his never say never attitude. Perhaps one day, I’ll apply for an international broadcasting license and do something similar. I wonder if he gets many RFI complaints from people living around his transmitter site. I once had one from somebody who was receiving the radio station on the outlets in their kitchen. Seems Larry King was not their thing…

More failure, please…

Sounds kind of silly, but in some cases, failure is good. Companies that are inefficient, poorly run, poorly conceived, have substandard products, do not serve their clients, and so on should be able to fail. This allows good companies, that do things right, to thrive.

Too big to fail is too big and those companies should be broken up. This holds true in the radio business as well as the banking industry, the auto industry, and so on. What is truly unfortunate is that the people most responsible for the failure, the upper management, and CEOs, often get away with millions while the people who had their back into it get to go to the unemployment office.

That being said, radio is in for some drastic changes soon.

NO BAILOUTS FOR RADIO

Enough already with the bailouts. Radio is not some precious national resource, it does not function for the betterment of society, nor does it provide vital information in the time of emergency. It stopped doing those things years ago when deregulation kicked in, deregulation which was lobbied for extensively by the NAB (National Association of Broadcasters) at the behest of radio and tv station owners, by the way.

Once deregulation took effect, station management went on a hunt for pennies, often tripping over dollars to get them. Through staff reductions and cost cutting, the product was deluded and the medium was marginalized and that is where we are today.

Not everyone followed the above narrative, there are some operators who stuck to the framework of public/customer service and kept good programming on the air. Those stations are few and far between but they are out there. Why should they not reap the benefits of their forward thinking?

AM transmitter preferences

Engineers are funny. We all have our likes and dislikes and our reasons for both. I don’t really like Harris products. Even when I was in the military, their stuff seemed a little “light.” I suppose having to deal with an MW-50B transmitter at my first full-time chief engineer gig didn’t help that impression. The MW-50 would “blow up” every six months or so. I say blow up because that is the only way I can describe it, no overload lights or any other indication of trouble until the blue lightning flashes and thunder from the PA section. What a POS.

Other Harris transmitters, such as the SUX-1, FM20H, Gates-1 etc have also left me less than impressed.

In order of preference, my choice of AM transmitters would be:

Any Nautel solid-state unit. Nautel makes good equipment that is well-supported.
Any BE solid-state transmitters. I favor the A model over the E model, but both are good. One condition, they must absolutely be well grounded and all of the toroid filters provided by the manufacturer must be used when installing.
Any tube-type Continental transmitter. There are older units, I believe 816R but they work well and sound good on the air.

Really, that is about it.