Transmitter Site Maintenance: Time for Spring Cleaning

| May 2, 2013

By Thomas R. Ray, III CPBE, AMD, DRB
Tom Ray Consulting
President   
TALKERS
Technical Editor 
NEW YORK — For most of us, spring has finally sprung, which is good news for that pesky groundhog.  I just came across an interesting recipe for groundhog stew.  Maybe next year.

But spring generally means spring cleaning.  I don’t know about where you are, but here in the northeast, the winter was a bear.  Snow, ice and wind can cause issues for your transmission facilities.  So it’s time to do a thorough inspection of your transmitter sites – both the main transmitter sites and anywhere you may have an STL transmitter or receiver.

Go out to the tower(s) and have a good look around.  Look up the tower.  If you utilize a folded monopole for an AM station, or if your tower has detuning skirts on it for another nearby AM station, observe the skirt wires.  They should be straight if they are tensioned correctly, and none of the fiberglass standoffs that the skirt wires run through should be moving in the wind.  If you notice loose or broken standoffs, you should make arrangements to have this corrected as soon as possible.  Eventually, if the wind is forceful enough, that skirt wire may touch the tower causing arcing.  Arcing in AM causes splatter which is interference, and it will be your responsibility to remedy the situation quickly to avoid an FCC fine.

While looking up the tower, make sure you do not observe any transmission lines that appear loose.

If your tower sits on an insulator (there are some FM towers co-located with AM stations that do, in fact, sit on insulators), look at the insulator.  Make sure there are no cracks.  If there is a corona ring on top of the insulator, make sure the weep holes, which are used to drain water from the ring, are clear.  If you need to clear them, make sure you do what is required to shut down RF power to this tower and ground it.

Look at the spark gaps (sometimes referred to as ball gaps or Johnnie Balls – FM stations, unless the tower is insulated, usually do not have these) – this is part of your lightning protection system.  Are they intact – do they need replacement?  Are they, in fact, attached to the station’s ground system?  Are they close enough together yet not close enough to cause arcing?

For AM stations, there is normally a connection between the tower and the tuning house or box.  This is normally a copper pipe, and it should be connected firmly (preferably welded) to the tower and the tuning box.  Tighten the connections if necessary.  Where the pipe flattens out, check to make sure the pipe is not ready to break.  If it is and you need to replace it, observe that there is normally a turn or two in the pipe.  This forms an inductor and is also part of the lightning protection system.  A lightning strike has a very fast rise time making it an AC signal.  AC signals do not like inductors, which is what the two turns or so in that pipe are.  Most of the strike’s energy will be diverted to the spark gaps to jump to ground rather than into your equipment which will turn expensive components into ashes.  Make sure you have the same number and diameter of turns in your replacement, as this may also affect the tuning of the system.

Look at the transmission lines that go up the tower.  Are they attached to the tower or swinging in the breeze?  Do any look dented by ice?  If there is an ice bridge or some other support structure to get the transmission lines between the building and the tower, are the lines firmly attached to it?

While you’re out at the tower(s), open the tuning house door.  Inspect the components in there – tighten connections.  Nothing is worse than a meltdown at a high current point when a simple twist of a screwdriver could prevent this.  And while you’re in there, sweep out the tuning house.

Back at the transmitter building, inspect the outside, including the roof.  If you have a rubber membrane roof, climb up there and take a good look at it.  I was at a transmitter site once where the chief engineer and I discovered a puddle on the floor directly in front of the main transmitter.  We were actually there because of a generator issue, and while he was on the phone loudly discussing the whereabouts of the service tech that was supposed to meet us at the site, and since the tower was right next to the building, I climbed up the tower and onto the roof – because there was a really good reason there was a puddle on the floor.  What I found was that the rubber material had cracked and split in numerous places – most notably in the spot directly in front of where the transmitter was located down below.  Needless to say, we made a trip to the local home store to grab a couple of tarps and some rope to put over the roof until the station could get a roofer there.  If that leak had been just eight inches farther back toward the transmitter, we would have been repairing a transmitter rather than waiting for a generator guy.

If your building is cooled by simply pulling outside air into the building, change the air filters (you DO have air filters over the air intakes, correct??).  While you’re at it, make sure the filters sit properly and repair their mounts as necessary.

If your building has air conditioning, now is the time to have the condenser coil cleaned and the entire system serviced – not when it has failed on that 98 degree day.

Check around the building for vermin.  Expandable foam is a wonderful invention and makes it easy to fill any gaps where mice and other creatures can enter the building.  You would be surprised what a mouse can squeeze through.

Weather strip the door and make sure the door has a good door sweep on the bottom.  This helps keep out snakes – there’s almost nothing worse than opening the door to the building, reaching to turn on the lights, and having something come down from up above and hiss in your face.  It will also help keep spiders out in areas where they are somewhat large.  I visited an AM station once and wanted to get a look at the tuning gear at one of the towers.  The Engineer opened the door and said, “Hang on a minute.”  He then proceeded to take something like a dust mop and go around the door and poked it inside the building and swirled it around.  I asked what he was doing.  His response?  “Making sure the black widows are out of the way.”  I settled for pictures taken from the doorway, thank you.

Sweep the floor.  Dust off the transmitter.  Open it up and clean it out – a  non-dusty transmitter tends to be a happy transmitter – and you’ll find out if you have any issues inside and whether you have any uninvited guests that got in to take advantage of the warmth.  Do the same with the equipment racks.

Finally, if you are a manager reading this, have you been to the transmitter site recently?  You should clear some time and go for a ride.  If you have never been to one of your sites, I highly recommend it.  There is at least one broadcasting company that has a company policy requiring their general managers to visit the transmitter sites at least once so that, a) they know where they are and b) so that the next time their engineer puts in a request for an item for the site, they have a general knowledge of what is involved at the facility.  I once worked for a general manager that always gave me a hard time whenever I needed something for the site.  This was a 50,000 watt AM station and the FM transmitter was also at the site.  On day, in frustration, I told him he really should come out to the site to see what was involved so that he wouldn’t think I was making things up all the time.  He took me up on the offer.  We spent the entire afternoon there, he with his mouth hanging open most of the time.  Before we went there, he had no clue what I did at the site.  He never argued with me again because he came away with an understanding of what it took to keep his stations on the air.

Spend a day or two at the transmitter now that it’s spring and go through the place.  You’ll probably find the site becomes more reliable with some tender loving care.

tbugk

Thomas R. Ray, III CPBE, AMD, DRB is president of Tom Ray Consulting and Technical Editor of TALKERS. He can be phoned at 845-418-5065 or emailed at tomray@tomrayconsulting.com.  His website is www.tomrayconsulting.com.  Meet Tom Ray at TALKERS New York 2013 on Thursday June 6.   

 

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Category: Technical