What’s Behind Box (Cover) Number Three?

Available: Nice mouse apartment, plenty of bedroom space, transmitter view

Check your transmitter electrical boxes. It is a quick but necessary maintenance chore.

Fig. 1: Who knows what’s going on inside the electric disconnect? Fig. 2: A clean box with tight connections.

One never knows what’s going on behind the cover (Fig. 1). It could be loose connections that will overheat and eventually fail or cause a fire. If you have an infrared thermometer, check each terminal for excessive temperature. The box may be clean, dry and show no signs of corrosion, as shown in Fig. 2. However, the cover may be shielding a much greater problem: mice infestation, as seen in Fig. 3.

Fig. 3: Surprise! Rodent infestation!

In this case, mice found a small hole in the rear of the box. That was their entry into a beautiful “apartment” in which to nest. If you discover such an infestation, pick up some heavy rubber protective gloves, wear a smock that you can throw away and use a face mask.

When it comes time to seal the entry, plug the hole or holes with stainless steel or copper wool mixed with expandable spray foam. The foam alone won’t work — the rodents will eat right through it. They do not like the steel or copper wool.

Fig. 4: Mouse droppings on the floor or the bottom of equipment racks are a dead giveaway your site has rodents.

Transmitter equipment is so reliable now that months may go by between visits. A more frequent and routine inspection is warranted; but if you’re handling 10 stations this may not be practical.

So when you show up at the site, take a quick walk around the building perimeter. Once inside, check the floor as well as the bottom of equipment racks. Mouse droppings, Fig. 4, are an instant clue to a problem. Take steps to plug their entry ways as previously described. Again, use protective gear when cleaning up the droppings. I prefer a broom and dust pan to a vacuum; vacuum exhaust just fills the air with unhealthy contaminants.

If you can’t find an obvious entry, try a nighttime visit. Leave the lights on inside the building as you walk around the perimeter in the dark, looking for light leaks. Remember, rodents are great contortionists; they can squeeze through the narrowest of gaps. I found the light trick useful in checking AM antenna tuning units at the base of each tower, too. As most of these towers are “hot,” it’s best to do your night walk when the station is down, to avoid an RF shock or burn. With the light illuminated inside the ATU, walk around the coupling box, again looking for light leakage. Seal any voids you find.

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San Diego’s Marc Mann wrote about growing up on the East Coast on Long Island, where there was a multitude of surplus electronic stores stocking an array of communications and military surplus electronic parts. Long Island was a hotbed of electronic manufacturing, supporting a number of government contract manufacturers. Canal Street, in the Bowery of lower Manhattan, was the place to find just about anything in used electronics.

Unfortunately these outlets are all gone. Whenever Marc travels, he tries to seek out what a city has left. Recently, in Phoenix, he found Apache Surplus (www.apachereclamationandelectronics.com).

That website is great but Marc also prefers a printed catalog, which is just what he found at Marlin P. Jones and Associates. Although their catalog is online, they also offer a paper catalog. Here’s the link for you to order a free catalog by mail: www.mpja.com/inforequest.asp.

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Fig. 5: Twenty-four LEDs make for a bright flashlight. Fig. 6: Hand-held, it can be suspended by its hook or built-in magnet.

Here’s another neat find, sent in by consulting engineer R. Morgan Burrow, P.E.

This worklight (Fig. 5) is a must-have for engineers. It combines a 24-LED worklight and a four-LED flashlight. The light has a swivel hook and magnet mount and comes with the batteries. Fig. 6 shows how bright the light is. Ace Hardware is the place for this handy work lamp manufactured by Blazing LED.

Contribute to Workbench. You’ll help your fellow engineers and qualify for SBE recertification credit. Send Workbench tips to johnpbisset@gmail.com. Fax to (603) 472-4944.

Author John Bisset has spent 46 years in the broadcasting industry and is still learning. He handles West Coast sales for the Telos Alliance. He is SBE certified and is a past recipient of the SBE’s Educator of the Year Award.


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