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Readers, Please Weigh in on These Questions

Also, here are some coffee maintenance and skin-care tips just for radio engineers

Broadcast engineer and inventor Joe Stack suggests an item that may be helpful for engineers: O’Keeffe’s Working Hands hand cream. Joe’s hands get dry in the winter months, and he ends up with cracks on them that can be quite painful.

Fig. 1: Heal dry, cracked hands with O’Keeffe’s Working Hands.

Joe has tried various solutions but says Working Hands is great. It’s not greasy and not scented, and it actually helps heal up any tiny cuts you might have.

Joe discovered the cream at Home Depot; places like Walmart have it now too. It’s about $7 and comes in a plastic screw top can, just like shoe polish.


Veteran radio and television engineer John Collinson writes that Tom Osenkowsky was absolutely correct when he wrote here about the importance of capacitance ESR in many circuits. He identifies audio circuits and switching power supplies as two of the paramount situations in which this is crucial.

The Sencore LC-53, LC-75, LC-102 and LC-103 are the most valuable tools John knows for thorough analysis on critical electrolytics. The downside? These instruments are almost impossible to buy.

Prices from numerous sources are often far higher than when the units were new.

To make matters worse, John has an LC-102, which has a problem that drives it far out of calibration — and he can’t find anyone who can fix it.

Someone must have ended up with the intellectual property when the company changed hands, so if anyone can point faithful readers of Workbench to a reliable repair facility for the great old Sencore test gear, that would be appreciated.

In the meantime, consider some of the newer ESR test devices found on the internet and mentioned in our column.


John Collinson offered additional comments that I want to share with you.

The first has to do with blinking LEDs. Back in the early 1990s, the radio stations employing John were using Wheatstone A500 consoles. Like everyone in those days, engineers were constantly changing the ubiquitous #387 bulbs used in the on and off buttons. Despite the resistors the manufacturer used to keep the filaments slightly warm, they still burned out.

John switched to LED replacements (after cutting out those resistors) and soon experienced a new phenomenon: After a couple months, some of the LEDs started flashing at maybe a 2–3 Hz rate. When one began blinking, it would always do so any time it was on, so it wasn’t intermittent in any way. John checked sockets, supply voltages, contacts — everything was fine.

Changing the LED “bulb” corrected it immediately, for a few more months. All channels experienced this problem sooner or later, and no one John talked to could explain the phenomenon.

On those LED replacements, you could actually see the tiny LEDs inside the end of the unit. As John recalls, there were two groups of four, and often one group would flash while the other one stayed steady.

By the time John left that station, he had collected a copious handful of bad units, and to this day he’s never heard anything in the physics of an LED which would explain this behavior. Then, last year during the NAB Show, John saw an LED replacement lamp in the hallway of a hotel and it appeared to have the exact same type phenomenon. Any thoughts, readers?


John also reminds us about the rodent infestation of transmitter site electrical boxes: Don’t forget your outdoor boxes! Critters love pad-mount transformers, which are nice and warm.

If you live in fire ant country, you know they seem to have a strong affinity for electrical boxes. Once John found them packed so heavily into the pressure switch on an outdoor well pump that they shut down the pump.

And it’s not just ants. Yellow jackets love the shelter of ATUs, which, if running slightly warm, can also attract snakes. It goes without saying that field mice certainly love these places, as well.

Sprinkle a few moth balls inside to keep the snakes out, and remember to seal holes and cracks.

John warns that like mice, ants will eat right through urethane foam and many types of caulk. Stainless steel wool (which resists rusting) is a better solution.

UHF transmitters, in the days before unitized beam supplies, often had individual “pole pig” type electric transformers that were good at converting snakes into grounding sticks.

John is living in Florida; he says power company personnel have told him that squirrels are their biggest nemeses. Their ability to chew through insulation and some metals makes them a nonstop headache.


We have discussed muffin fans in the column, focusing on uses for these compact cooling devices. Although John Collinson lacks a picture, he’ll paint one with words. John was known for consuming copious quantities of coffee but not having the patience to wait for it to cool down to chugging temperature. One of his engineers took a spare muffin fan and tie-wrapped it to a 7-inch plastic tape reel (for stability), and immediately he had a great little coffee cooler.

(Our editor Paul McLane writes: “Where’s a photo when you really want one?”)


On that note, here’s another coffee tip.

In one of my Workbench SBE presentations a few years back, I showed a coffee warmer designed by West Virginia Radio Corp.’s Randy Kerbawy.

Randy took a large metal coffee can and cut a cave-type entry in the side, using a nibbling tool. He made the passageway large enough to fit his Weller soldering iron and stand inside. The coffee cup sat on top of the can, which was warmed throughout the day by the hot soldering iron.


We’ve written about Serial-over-IP adaptors in the past, and John Collinson wrapped up his informative note saying he has tried a few.

It’s been his experience that these work great in-house, across a LAN, but he has yet to find one that works well across the public internet. John suspects they can’t handle the jitter.

Again, do you have any thoughts and experiences you want to share? Email them to me, along with your snail mail address, so we can recognize you.

Contribute to Workbench. You’ll help your fellow engineers and qualify for SBE recertification credit. Send Workbench tips to [email protected]. 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 a past recipient of the SBE’s Educator of the Year Award.