Now You See It, Now You Don’t!

Remember the pesky problem of infrared remotes not working in fluorescent light environments?
By John Bisset,

Remember the pesky problem of infrared remotes not working in fluorescent light environments?

Michael Miller, the AV technician for two high schools in Royal Oak, Mich., has a novel solution.

First, a little background: A few years ago, his school lighting was upgraded to GE type F32T8-SP35 fluorescent bulbs. After the upgrade, Mike was swamped with complaints that television remotes had failed, and in some cases, TV sets would turn on and off all by themselves. Talk about disrupting classrooms!

As Mike investigated, a teacher offered a clue that the problem was related to the fluorescent bulbs. She said the remotes worked fine when the classroom lights were off. When the lights were on, the remote acted like it had no battery. Nothing worked.

Mike’s first thought was that the new bulbs were emitting an unusual amount of infrared waves in the spectrum. After a discussion with a GE design engineer, he was assured that there was very little infrared radiation from this lamp. The engineer added that the sensor on the television set senses visible light along with infrared and therefore could be overloaded by visible light, and so becomes inoperative.

This statement led Mike to explore the idea of filtering out visible light without affecting the infrared control signal. His theater lighting background drew him to a Rosco Cinegel swatch book. Mike found a neutral density gel in the book, and the associated transmission graph showed little filtering at the infrared frequencies.

If you refer to the Rosco Cinegel book, you’ll find the gels calibrated in standard photographic f-stops. Typically, the gels are available in one, two or three stops, which correlate to a reduction of 50, 70 or 87.5 percent, respectively. In almost all cases, a three-f-stop gel did the trick. If additional attenuation is needed, just sandwich an extra f-stop or two.

The three gels that Michael used were Rosco Cinegel #3402 (one stop), #3403 (two stops), and 3404 (three stops).

The really good news is that the problem was solved on more than 100 television sets with less than $10 worth of materials. A square inch of gel was placed over the television IR sensor, and in some cases affixed with black electrical tape. If the gel gets lost, it’s easy to replace.

Thanks, Mike, for a novel solution, borrowed from our theater lighting technicians.

. . .

(click thumbnail)Figure 1
What does your tower base look like? Figure 1 shows an AM base where the vegetation has been treated by a defoliant such as Round-Up brand, but the area still needs to be cleared.

Remember, the roots of small trees, such as those up against the fence in the photo, can rip ground screen and/or radials if pulled by the roots. If you trade the services of a landscaper to clean inside your tower fences, supervise their work – and also keep in mind RFR exposure limits.

After clearing the area, cover the ground with landscape fabric or black plastic. A covering of pea gravel or sand will reduce further vegetation growth.

. . .

A few years ago, Terry Jordan, engineering manager for Cape Fear Broadcasting, now part of Cumulus, was planning a building expansion.

(click thumbnail)Figure 2
His dilemma: the architect had designed the visitor’s parking lot in close proximity to one of the tower guy anchors. Not wanting to tempt fate by leaving the anchor exposed, Terry started evaluating his options.

Fencing was the first, but aside from expense, a fence does a poor job of stopping an automobile. That’s when Terry settled on a more economical, aesthetic and sturdier solution.

The steel posts shown in Figure 2 were set in concrete and painted. They were located beyond the anchor concrete pier, so any shock from a car slamming into them would not damage the pier.

. . .

The saga of rodent removal from transmitter sites continues.

Sid Schweiger from the Entercom Boston cluster advises readers of that the latest generation of electronic gizmos are startlingly effective in removing rodents.

Sid tells a horror story of mice destroying the generator at a previous station, requiring a $3,000 rebuild. That got management’s attention. Sid bought three of the electronic repellers (total, about $30), and placed them around the transmitter building. He cleaned up the mice messes and nests, and waited the prescribed two weeks. Not a trace of the little furballs.

A nice side benefit was that snakes appeared to be repelled by the sonic controllers. They’ve disappeared, too!

It’s a good idea to check conduits as well. Old or new empty conduits, or open-ended conduit pipes that run outside to the tower or generator, provide easy access to the inside of the building.

Here’s a sealing method that should be helpful. Buy a package of steel wool. Tear off a piece that will fit snugly inside the end of the conduit. Tie a wire or string around the piece of wool, prior to stuffing it into the conduit. This "pull string" facilitates removal of the wool stuffing if the conduit is needed.

After stuffing the end with the wool, cap the conduit end with dum-dum (a clay-type compound found at electric supply stores), tape or an end-cap, also available from electric supply stores.

The logic behind the process is that if a rodent chews through the seal, the steel wool will stop them. If they’ve traveled from the other end of the conduit, again, the steel wool will end their journey.

A little preventive maintenance now will prevent rodents from chewing through wires and taking you off the air later (Friday afternoon drive, of course!).

Submissions for this column are encouraged, and qualify for SBE recertification credit. Fax your submission to (703) 323-8044, or send e-mail