Now that spring is upon us, many hibernating chipmunks and ground squirrels have set about building their underground burrows. Unfortunately, the sand that fills cable trenches or surrounds underground tanks can be easily displaced by rodents.
In Fig. 1, New Hampshire Public Radio’s Steven Donnell shows what he found when inspecting an underground propane tank.
Recently we suggested using Mouse Magic-brand rodent repellant packs (manufactured by Bonide, www.bonide.com) around the interior of your transmitter building, storage/generator sheds, or AM antenna tuning units. Looks like we can add propane tanks to the list of useful locations for Mouse Magic.
By the way, although garden centers sell Mouse Magic, a pack of 12 is available on Amazon for under $20.
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Industry veterans will know Chicago engineer Warren Shulz. He tells us he was having a roof replaced and needed a new outdoor FM receive antenna.
Simple enough? Well, Warren reports that finding a replacement was like looking for a buggy whip. With VHF-TV low-band now silent and with the DTV migration, every antenna Warren found was UHF or high-band TV. The lowly FM-band Yagi roof antenna, it seems, was nearly extinct!
It took a lot of internet search time to find a replacement roof antenna, but his effort paid off. Warren found an eight-element 6-foot long Yagi for under $100.
It’s been Warren’s experience that an outdoor roof antenna is required to receive FM-HD2 at the 28-mile distance from city transmitters, as there is no HD reception using an indoor antenna.
Apparently, Warren is one of the few who feels an outdoor FM receive antenna is important. Unfortunately, sellers flushed low-band TV analog and FM-band antennas after sales dropped and UHF-DTV took off.
If you’re interested in what Warren bought, head to http://dennys-tv-antenna.mybigcommerce.com/fm-radio-antennas.
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And speaking of things you can’t find, have you heard of SWAR Grees?
From the Radio Society of Great Britain, here’s the link: http://rsgb.org/main/swar-grees-standing-wave-improver. The grease is supposed to improve VSWR — just smear it liberally on the transmission line!
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Bible Broadcasting’s Steve Tuzeneu recommends https://www.everythingrf.com/rf-calculators for engineers who need to make RF conversions and calculations. The site provides basic conversions like Fresnel zone calculations, free space path loss, as well as calculating wavelength and resonant frequency of RF circuits.
There are even apps for your mobile device — head to Google Play or the App Store to download your free mobile app.
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Malaysia’s Paul Sagi invites readers to a unique “Tool Hacks” YouTube channel where you’ll see how to make an inexpensive wire stripper from a clothespin and a pencil sharpener or using a rubber band to remove a stripped Phillips screw.
Here’s the link: www.youtube.com/watch?v=SQdn_TvryeE.
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Microfiber cloths are useful for cleaning monitor screens and other delicate surfaces. Broadcast engineer Joe Stack writes that for about $3, you can pick up a 12-by-12-inch 3M Scotch-Brite-brand microfiber cloth. Cut the larger sheet into four equal pieces, and include a piece with the station’s remote equipment. You can get the large cloths at a Target or Walmart.
Joe used to just look for the small microfiber cloths, but found it more economical to cut down the larger size, since micro fiber cloth stays intact and doesn’t unravel when it is cut. Fig. 2 shows the cloths ready to go.
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Even with weatherproofing kits, moisture can find its way over time into coaxial RF connections.
KSL Salt Lake Engineer Jeff Sory had an STL transmitter fail. Investigation found water had found its way into not only the transmission line but also the STL dipole — see the corrosion pictured in Figs. 3 and 4.
Replacement coax and a new dipole got things back to normal.
Contribute to Workbench. You’ll help fellow engineers, and qualify for SBE recertification credit. Send Workbench tips and high-resolution photos to [email protected]. Fax to (603) 472-4944.
Author John Bisset has spent 48 years in the broadcasting industry and is still learning. He handles Western U.S. Radio Sales for the Telos Alliance. He is SBE certified and is a past recipient of the SBE’s Educator of the Year Award.
