Does the enclosure for your AM antenna tuning unit need to be replaced?
Frank Hertel, principal engineer with Newman-Kees RF Measurements & Engineering, offers a reasonably priced alternative. Why not consider a “belly box” to house your RF components?
These underbody truck boxes are large enough for most ATU components. They’re weatherproof. Most come with a waterproof rubber seal along the hinged front cover.
They are sold in a variety of sizes and come in powder-coated steel or unpainted aluminum. Starting prices on Amazon are about $175. Also look around for other online sources. The one in the photo is from tool company Vevor. Or try Elite Truck.
Most of the time, Frank buys containers from local truck industrial accessory stores. Rural King farm and hardware stores keeps several models on hand.
With cooler weather upon much of the country, now is a good time to check inside your AM coupling networks. With the transmitter off and the breaker thrown (to avoid it being energized), open the enclosure. Use care; wasps or hornets may have invaded the enclosure.
Open the J-plugs on the network input and output before you check all connections for tightness. Inspect components for signs of overheating or arcs. Clean out the enclosure. If you make your inspection at night, place a battery-powered LED light inside, seal up the enclosure and walk around it looking for light seepage. Plug small holes with rubber silicone or caulk. For larger holes use stainless steel or copper wool.
When you’re ready to button things up, it’s not a bad idea to apply power and calibrate the remote RF ammeter to the base current meter. Note the calibration results in your station maintenance log.
LED warning indicators
Don Kiser, AC2EV, is a process controls engineer in New York and has been using Banner WLS15 Pro programmable LEDs at work for some time. The digital inputs allow Don to set a pre-programmed color and automation sequence based on product information.
Don writes that in a radio setting, the programming could be triggered by more than just the on-air mic. How about a visual reminder for a commercial break, live traffic report or 30-second warning that the song will be ending?
For the transmitter site, the color could be based on transmitter status: red for off, yellow for standby, green for on. Banner Engineering offers a variety of products at www.bannerengineering.com. The company also manufactures a variety of level sensing devices. One of their sensors might be appropriate if you need to monitor fuel level in your generator.
Gracie’s foam CatchBox
Gracie Slentz is following in her father Dan’s footsteps by providing neat tips for broadcasters. She told us about an unusual microphone system used in large auditorium classrooms at Kent State University.
It’s called the CatchBox. It consists of a wireless mic built into a foam box. In a crowded setting you toss the mic to the person who wants to speak. The CatchBox mutes while it’s being thrown and has a slight delay in un-muting so there’s no “thump” when it lands. The Plus version lets you choose up to four audience and presenter microphones to connect to the hub.
Use it to get a mic quickly to whomever is speaking. This could be helpful on remotes as well as more formal settings, like a zoning meeting. And it’s got a massive branding surface, useful in radio. Check it out here.
Thanks, Gracie, for your first Workbench submission. You made your dad proud!
Don’t rely on just a lock
Mark Peterson is an engineer with AM station WCTS in Maplewood, Minn. He read with interest my colleague Ty Magnum’s recent commentary in Radio World about tower security.
Ty’s comments on padlocks reminded Mark of several YouTube videos showing how easy it is to open padlocks. You can find some by searching YouTube for phrases like “breaking a padlock with wrenches,” “insane way to open any lock without a key” and “these 13 secret ways let you open any lock.”
The videos might be clickbait but they also offer a cautionary reminder to augment your padlock security with site security cameras and signage.
Workbench submissions are encouraged and qualify for SBE recertification credit. Email johnpbisset@gmail.com.
