The last AM station

AM; it has a future or not?  I cannot make up my mind sometimes.  As some AM stations can and do make a profit, many others do not.  Truth be told, the engineering effort that goes into an AM directional antenna is becoming a black science.  And some people may say, “oh, but that gives you job security,” but that is not usually how it works.  Instead of paying somebody more money (or any money) to maintain something, the business philosophy these days seems to be to chuck the baby out with the bath water.  Because after all, if not AM then FM right?  Yes, of course!  Except, the very thing that happened to AM is happening to FM too.  Increasing noise floors, jamming signals into every possible nook of the frequency spectrum, no thought toward technical facilities and infrastructure, and horrible, horrible programming will result has resulted in the decline of listening for FM too.  Mark my words and the date; FM broadcasting will suffer the same fate as AM if current trends continue.

Guy wires in trees
Guy wires in trees

How will it end?  I would hazard with more of a whimper than a bang.  I imagine something like this:

One day, in the not very distant future, at an AM station somewhere, the transmitter faults and goes off the air. Chip, the computer guy, goes in the back room, moves a bunch of cleaning supplies, cases toilet paper, a garbage can and the remote gear out of the way so he can reach the ON button on that box the old guy told him about. The big box makes some clunking noises and comes on for a second, but then the fault light called “VSWR” or something comes on and the transmitter shut off again.

Chip, the computer guy, remembering what the old guy said about that big tall thing behind the building, pushes the back door open.  What used to be a field is now completely overgrown with weeds, brush, and trees. He follows the pipe from the back of the building, through the prickers until he comes to an old fence, which is falling down. He pushes on the locked gate and it falls off the hinges. Inside the fence, there is a rusty tower and a white box. Finding the box unlocked, he opens it and sees a baffling array of metal coils, copper tubes, and black round things. He sees that one of the black round things is cracked in half and black goop is coming out of it. The computer guy takes a picture with his cellphone and emails it to the market manager/vice president of sales.

A few minutes later, the the market manager calls back and Chip tries to explain what is going on, stating the the transmitter went off and the black thing in the box by the tower looks broken.  The market manager/vice president of sales asks “Has anyone called and complained?”  Chip says no, not that he is aware of.  The market manager says, “Eh, fuck it leave it off.”

The end.

The Isolated Ground

We get requests to install Isolated Ground outlets from time to time, especially with sensitive equipment. TELCO likes to have isolated grounds on their fiber MUX’s.  It can become an issue with branch circuits in split-phase or three-phase services that share the same ground and neutral conductor.  This can lead to a ground loop between neutral and ground, which will create all sorts of havoc in a broadcast facility.

20 amp, 120 volt Isolated Ground Outlet
20 amp, 120 volt, Isolated Ground Outlet

The National Electrical Code covers Isolated Grounds (IG) and sensitive equipment in several sections.  The first is section 250.146(D), which states that the installation of isolated ground receptacles is permitted.   The grounding conductor connected to such receptacles is permitted to pass through one or more panel boards, boxes, conduit bodies, etc without being bonded to them.  However, said panel boards, metallic boxes, conduit bodies, raceway, etc must also be grounded separately.  That means running two ground conductors, usually, the isolated ground conductor is green with a yellow stripe or spiral.

Studio electrical diagram isolated ground
Studio electrical diagram isolated ground

The second is section 640.9(A), which refers to separately derived power systems.  This section deals specifically with balanced power; 60 volts AC to ground.  In such cases, a separate ground conductor is allowed as outlined in section 250.146(D) and in 647.6(B), which states that the grounding buss should be connected to the grounded conductor on the line side of the separately derived systems disconnecting means.

Other sections of the NEC that may apply to broadcast radio and television facilities:

  • Article 455, Phase converters (rotary phase converters)
  • Article 480, Storage batteries (UPS)
  • Article 520, Theaters, Audience Areas of Motion picture and Television studios, Performance areas, and similar locations
  • Article 640, Audio signal processing, Amplification and Reproduction Equipment (Audio wiring)
  • Article 645, Information Technology Equipment (computer equipment and network wiring)
  • Article 647, Sensitive Electronics Equipment (balanced power 60 volts to ground)
  • Article 702, Optional Standby systems (generators)
  • Article 770, Fiber optic cables
  • Article 810, Radio and Television Equipment (antennas, towers, and grounding)
  • Article 820, Cable TV (CATV)
  • Article 830, Network-powered broadband communications systems (power over ethernet)

If interested, I can do articles on these sections as well.

Windows XP

WDST technical operation center
technical operation center

It is time to plan and upgrade those machines running Windows XP. After April 8, 2014, Microsoft will no longer be updating the software and/or patching security holes. Many in the IT industry believe that after that date, hackers will attempt to break the popular operating system which has been in use for twelve years.

Approximately one-third of all Windows operating systems in use today are XP.  Microsoft has already warned users that potential hackers could use security patches and updates for Windows 7/8 systems to scout for vulnerabilities in XP.  I know several radio clients have automation systems and office networks that run primarily Windows XP.  Microsoft may be overstating the risks of remaining on XP, then again, they may not be. This situation has been described in several trade magazines as “A ticking time bomb,” or equally dire:  “Microsoft urges customers up upgrade or face ruin.”

In radio station infrastructure, very few systems are as vital as the audio storage and automation system.  Without a functioning automation system, most stations would be dead in the water.  If an automation system were to hack and be ruined completely, I do not think there are enough people left on most stations’ payrolls to run an operation manually, even for a short period of time.   I, for one, do not want my phone to start ringing on April 9th with a bunch of panicky managers talking about how unacceptable the situation is.

Failed High Voltage Contactor

This contactor was used to replace the Furnas contactor installed as original equipment when the transmitter was manufactured in 1986.  Furnas is no longer in business, thus the ABB A145-30 was substituted. It was purchased directly from Broadcast Electronics for an FM35A transmitter:

ABB A145-30 contactor
ABB A145-30 contactor

It was installed about 18 months ago and has been in nearly continuous use since.  The broken white plastic housing surrounds the contactor coil and is responsible for pushing and holding down the contact fingers.

ABB A145-30 contactor coil cover
ABB A145-30 contactor coil cover

Looks like the coil is running too hot and damaging the plastic. This resulted in a failure of the contactor to make and no high voltage to the transmitter PA.  Obviously a problem.  I spoke to BE about this and they did not have a good answer.  Actually, what they said was “That contactor is rated for 220 amps,” which is true enough. The only thing that I can think of is the coil is rated for 208 volts and the transmitter is connected to a 240-volt delta service.

A new contactor was ordered and installed yesterday.

I will investigate the coil voltages further, but for now, the 27-year-old transmitter remains on the air.

Broadcast Electronics FM35A
Broadcast Electronics FM35A