Fig. 1: This bees' nest on a doghouse door helped two engineers diagnose a DA problem. Tom Ray is a vice president and the corporate director of engineering for Buckley Radio, based at WOR in New York City. Recently, Tom traveled to the Buckley Hartford stations, where he and Chief Engineer Scott Baron discovered some interesting helpers: Bees.
The station in Torrington, Conn., WSNG, seemed to be having problems whenever it got hot outside. Parameters for Tower 1 of the three-tower DA would go nuts and the transmitter would refuse to run at 1 kW. After a while, things would return to normal.
At the site, the duo inspected the tower feed point and looked up at the guy wires, part of which form a capacitive top hat. All looked good.
Inside the ATU doghouse, Tom studied the tuning network, looking for anything — an overheated coil clip, a carbon trace on a coil from a lightning strike, a mica capacitor just starting to ooze — but found nothing obvious.
It was then that Scott discovered the bees' nest right at the top of the door, seen in Fig. 1, as well as a couple of rather annoyed-looking bees studying them both.
Scott and Tom had brought sticks to poke at the tuning network components; Scott used his to take a swing at the nest. This caused to door to fly open further.
Fig. 2: When the door swung open, it shook the transmission line. As you can see from Fig. 2, the transmission line runs into the building right on the side of the door hinges. As the door moved, it hit the transmission line, and the transmitter popped off the air.
After Scott turned the transmitter back on, Tom started trying to flex the transmission line to get the problem to recur. Nothing, until he gave the line a kick. The transmitter popped off the air again.
Scott noted that the transmission line moved near the connection point when Tom kicked the line outside the doghouse. Scott put his ear near the line, being cautious of the tuning network components. Tom kicked the transmission line again. Scott heard a faint "pop" and the transmitter dropped off. (There is only about 150 Watts in this tower, not much to listen for.)
Now, inspecting the connection to the J plug, they didn't like what they saw, so it was off to Home Depot. When they returned, they signed the station off and disconnected the transmission line from the J plug.
The transmission line is Times cable from the early 1960s. The jacket says RG-213U, but the cable is easily 5/8 inch in diameter. As he removed the cable, Tom noticed there was no center insulator showing. As a matter of fact, he had to trim back almost 4 inches of jacket before he could feel the insulator between the braided shield and center conductor.
Basically, the center conductor was passing through 4 inches of nothing between it and the braid. When the cable moved, the center conductor would contact the braid and — "pop!" — off the transmitter would go.
Fig. 3: The completed repair to the transmission line ensured no more shorting. Tom and Scott deduced that it was wind, not the heat, that was moving the cable, causing the momentary short. The fix was straightforward and can be seen in Fig. 3. They trimmed things back and reconnected, and all has been well.
Not imagining how that insulation could have been trimmed back that far without damaging the braid, which was undisturbed, Tom figures it just shrunk after 40+ years.
And if it weren't for the bees, who knows how long it would have taken to diagnose the problem?
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Have you bookmarked www.fcc.gov/eb? The information on the Enforcement Bureau's home page is interesting, useful and sometimes entertaining.
Under "Broadcast Complaints" selected from the index at the left, you'll find Public File Requirements as well as information on EAS and Antenna Structure Registration. Further down the selection column is Field Issued Citations, NALs (Notices of Apparent Liability) and NOVs (Notices of Violation).
In addition to providing interesting reading, this part of the site can give you a good idea of possible sources of liability and fines around your own station.
The site is replete with notices to pirates (unlicensed broadcasters), land mobile violations and issues with other non-broadcast services. Looking at the quantity of notices, one sees how busy the FCC field offices are.
Among the broadcast actions — keep in mind you have to dig for these — was a station that was using a 3-foot-high plastic "snow" fence as security around the base of its hot AM tower!
You'll read about other broadcast problems such as inoperable EAS equipment (no power supply connected); no designated chief operator; failure to post the antenna registration number; failure to review, sign and date station logs; and leaving tower fence gates unlocked.
All simple stuff; but the notices are a stark reminder that you must keep your site maintained properly.
An idea: Print one of these every week or so and drop it on the manager's desk. It will help your manager know you are aware of what's going on and reinforce to the manager that you have legitimate work to do at the transmitter site. Especially in this economy, reminding your employer of your value — and what could happen if you aren't around — makes sense.
Thanks to Bruce Blanchard, chief engineer at WSCL/Salisbury University, Salisbury, Md., for sharing the site information.
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Mark Hoenecke handles engineering for Wisconsin Public Radio stations WHRM(FM) and WLBL(AM-FM) in Wausau, Wis. Mark read the July 15 Workbench item about using the footage indications printed on wire to measure how much wire is left in a box or on a spool.
Mark remembered what he used to do some 20 years ago when he needed to keep track of partially used reels and boxes of wire. Back then the wire did not have foot markings on the jacket so they weighed each new box or reel of wire and wrote the weight on it.
By using the proportion of new product weight to the packaged footage (they used mostly 500- or 1,000-foot spools), any remaining quantity could be weighed and the footage calculated. He found this trick to be accurate enough for figuring whether the spool contained enough wire to do a job. The weight of the box or reel was negligible.
Of course, nowadays just about every kind of wire and cable has footage markings on the jacket, and that makes life a lot easier.
Thanks, Mark, for reminding readers how it used to be done, and giving a suggestion if a jacket isn't marked in feet. Mark Hoenecke can be reached at firstname.lastname@example.org.
John Bisset has worked as a chief engineer and contract engineer for 39 years. He is international sales manager for Europe and Southern Africa for Nautel and a past recipient of SBE's Educator of the Year Award. Reach him email@example.com. Faxed submissions can be sent to (603) 472-4944.
Submissions for this column are encouraged and qualify for SBE recertification credit.