Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now


Springs, Boots and a Rodent Trap

Keep ‘meeces’ out of your transmitter with this clever trick

Fig. 1: Add some tension to your microphone arm springs. When I talk to engineers about submitting an idea of theirs to Workbench I often hear this response: “Oh, everyone knows that tip!”

Judging from comments received about Frank Hertel’s submission on differences between 75-and 50-ohm Type N connectors, though, quite a few readers learned something. Glad we could enlighten you. So as we start a new year, make it a point to share something you know with other engineers by sending us a tip. Email [email protected], and include high-resolution pictures if you can.

* * *

A number of years ago, when we couldn’t find a presenter for our Society of Broadcast Engineers meeting, we just went around the room discussing nuggets of engineering wisdom we’d picked up over the years. I dare say no one left without a handful of good ideas. That’s an idea in itself.

* * *

Speaking of good ideas, wouldn’t you like a dollar for every spring-loaded microphone arm sold? There certainly are a lot of brands and styles in the field using tension springs to hold the mics in position. Yes, you can buy new springs when the originals eventually wear out — or you can add this tensioner using the existing weak springs (seen in Fig. 1). A simple idea, and it works.

* * *

Jim Appleton is a retired chief engineer who sent in an excellent tip — especially should you need to install a new phasor.

Fig. 2: Try polystyrene for insulator replacement. With the power off, take the time to use a digital capacitance meter to unhook and measure each capacitor. Then with a felt marker, print the measured capacitor value right on it or next to it. This simple step will help you check the actual measured value compared to the manufacturer’s value. If something changes, you have a baseline measurement from which to compare future readings. Another advantage is that if you lose a capacitor and you have a junk box of replacements, you can choose a replacement capacitor close to the original measurement.

Once a year, Jim also took the station down for overnight maintenance and checked all capacitors, tightening all screws, nuts and bolts, remaining careful not to over-tighten them. This is also a good time to remove any and all critters and their nests. Scattering a few mothballs in the bottom of each ATU and phasor cabinet will help ward off snake and rodent trespassers.

While you’re in the doghouses and phasor, use that felt marker to note the position of coil clips on the inductors used in the networks. Again, if a clip falls off, you’ll know where to reset it. Thanks, Jim, for the great ideas.

* * *

I love it when our television brothers and sisters weigh in on a Workbench topic.

Roberta Barmore is with Dispatch Broadcast Group’s WTHR, Channel 13 in Indianapolis. With respect to our tip about substituting PVC for ceramic insulators in lower-power AM RF applications, Roberta writes that plastic supply shops still sell polystyrene, which is a better-behaved RF insulator than PVC. “Styrene” fittings, used for drain lines, are also made of polystyrene.

As for ceramic replacements, Roberta suggests checking with surplus dealers or hamfests for real ceramic insulators. You can often find a “will-fit,” especially for AM-band uses (as shown in Fig. 2), where there’s some “wiggle room.”

* * *

Platinum Tools announced the launch of RJ-45 Boots. Now shipping, the boots are designed to work on standard RJ-45 and EZ-RJ-45 connectors. The boots reduce the chances for broken or damaged connectors and locking tabs, as well as wire stress. The boots are color-coded and can be supplied in a variety of colors such as black, white, red, orange, blue, gray, green, yellow and purple — seen in Fig. 3.

Fig. 3: Colorful RJ-45 boots protect connectors.

For pricing and information on Platinum Tools and its product line, visit

* * *

Frequent Workbench contributor Hal Schardin shared a couple of links on the Pubtech forum, and thought our readers would benefit as well. The links describe a resettable mousetrap, which can be really useful around transmitter sites (and hopefully not needed around the studio).

The beauty of this device is that it uses commonly available parts: a bucket, soft drink can or bottle, a coat hanger and some peanut butter. To borrow a slogan from a famous infomercial, “You set it, and forget it!” Rodents of any type can wreak havoc at a transmitter site. The object of this trap is to offer something better than wire to chew on. Placing this resettable trap outside the building is effective, as described in a YouTube clip you can find by searching “Bucket Mouse and Rat Trap” (posted by user “maryannscupboards”).

Slight variations of construction exist. Hal chose the cola can and a coat hanger for wire to suspend the can. He also used two pieces of 3/4-inch PVC pipe to keep the can centered.

Not, perhaps, the most humane trap, but then neither is a glue trap, and I’ve seen those traps snare birds. Thanks Hal for helping us keep our sites rodent-free.

Contribute to Workbench. You’ll help your fellow engineers and qualify for SBE recertification credit. Again, please send Workbench tips to [email protected]. Fax to (603) 472-4944.

Author John Bisset has spent 44 years in the broadcasting industry and is still learning. He is SBE certified and is a past recipient of the SBE’s Educator of the Year Award.