Wow, That’s One Hot Mic! - Radio World

Wow, That’s One Hot Mic!

Need a Place to Put a Soldering Iron While You’re Working in the Studio?
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Fig. 1: A handy way to hold a hot soldering iron.

Have you noticed that you can never seem to find a place to put a hot soldering iron while working around a studio?

The answer might be right under your nose.

Randy Kerbawy is director of engineering for Southern Communications in Beckley, W.Va. He didn’t want to stick a hot iron in his tool bag and happened to notice an empty mic stand nearby. The result is seen here.

It occurs to Randy that a stand would also work as a third hand in some applications.

By the way, after years of saying he would do it, Randy finally broke down and got his ham license in July, and upgraded to General in December. When he wrote to us he was planning to put up some HF antennas.

? ? ?

Joe Stack does contract and project work in the New York City metro and beyond. He recently encountered an issue with Idec brand pushbutton switches typically used on AM phasor control panels. These are the big, heavy-duty, round, lighted switches that you see mounted on the control panels such as in Fig. 2.

They come standard with a set of normally-closed contacts and another of normally-open contacts. You can add more normally-open/normally-closed contact sets by stacking sections on to the back of the switch.

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Fig. 2: Idec pushbuttons are used widely for phasor control panels. In Joe’s situation, the last section of a 4PDT (four-pole, double-throw) switch was stuck closed. There is a little green tab that pokes out of the end of the switch section to activate the next switch section, as seen in Fig. 3. At the end of the fourth switch section, because there are no more sections attached, you can see the little green tab poking out when the button is pressed.

Somehow, this fourth, normally-open section was stuck “on,” which was obvious when Joe saw the green tab still sticking out even when he was not depressing the pushbutton. Joe pressed the tab back in with his finger and worked the pushbutton a few times, and it is not sticking anymore.

This phasor controller is run automatically by a computer, so the front-panel pushbuttons don’t get used a lot. Inactivity might be the reason it got stuck.

A frustrating side effect was that the stuck section was keeping his DX-10 in “medium” power while it was stuck “on.” It’s interesting that plain old switch contacts and relay contacts, along with a 24 volt power supply, can make for a full night of troubleshooting and head-scratching. We’ve all been there, right?

As a precaution, Joe decided to order extra Idec switches and Idec relays (both momentary and latching type) to have on hand for the phasor controller. Some of the relays are becoming hard to find.

Thanks, Joe, for the great troubleshooting tip. It’s ironic that some of the worst troubleshooting adventures are usually the simplest.

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Fig. 3: Here’s the rear of the switch, showing the green actuator tab.

? ? ?

Tom Norman is a CPBE and senior engineer with Burst Video. Tom writes about our discussion of using a 60 watt light bulb to heat a cabinet space.

Tom spent several years in American Samoa as the CE of the television stations there. He learned that if he wanted to keep mold from forming on things in a closet, a 60 W bulb or two would keep the temperature in the closet above the dew point, day or night.

It actually helped. He used the bulb idea in his bedroom closets too, and noted that in systems incorporating relays that were exposed to ambient air, the warmth seemed to work there, as well. Since the humidity hovered near 100 percent most of the year in American Samoa, raising the temperature to keep it well above the dew point seemed to make a difference.

But Tom also recalls an FM site not in American Samoa that was warm only as long as the transmitter was on the air. The room was brutally cold otherwise making maintenance difficult and dangerous. Perhaps having equipment that must be kept warm at all costs is a good thing; it may save a few fingers or lives in the longer view.

That

Workbench

column brought to mind a situation Tom encountered relative to keeping building temperature in line.

A transmitter site he maintained had a means to thermostatically servo-control dampers to enable cool outdoor air to enter the building based on thermostatic need. The dampers mixed cold outdoor air (swamp cooled in summer) with warm air from the transmitter and re-circulated the combined air into the building.

The engineer who installed it decided he only needed to run the system and associated fans when the transmitter was running. Thus, he used a pair of available contacts in the transmitter’s control ladder to control a contactor.

He did this by looping the contactor’s 115 VAC through the relay contacts. That meant that with all power removed from the transmitter, there was still live 115 VAC in the control ladder.

Yes, Tom fixed that the night after he got zapped. It’s a lot harder to get hurt by 12 Volts that have been current limited to less than 5 mA!

Tom’s experience is a reminder to any engineer taking over a new site.

During a maintenance session at a new station, an assistant and I systematically would turn off each breaker and note which circuits were affected. Sound like a waste of time? At one site, we found no less than four circuit breakers assigned to the transmitter control wiring. Even when the transmitter mains breaker was thrown, there were still four live breakers feeding the circuits.

? ? ?

Bill Tennant is an engineer with CBS Radio in Chicago. Responding to our mention of Web sites you couldn’t live without, he writes about how much time and money he’s saved his employer over the last few years by using

www.findchips.com

.

One of the neat features about this site, Bill writes, is that there is absolutely no advertising clutter. The site will search more than 20 distributors for a specific chip.

He also suggests Full Compass at

www.fullcompass.com

as a distributor with great bulk-quantity pricing for Neutrik brand connectors.

Thanks, Bill, for the sites, and for the reminder to let management know when you are saving them money.

? ? ?

In an earlier

Workbench

, we showed

a photo of laminate flooring

to be used under the “air chair” in a studio.

Scott Schmeling of Radio Mankato in Mankato, Minn., writes that in 1994 he and his staff redid one of their control rooms. Rather than place carpet under the chair (for the very reasons we mentioned), they opted for heavy-duty linoleum tiles. The tiles were about 1/4-inch thick.

Today, the tile has nearly worn down to the concrete — after some 15 years. He doesn’t think a laminate wood floor would last that long.

Thanks, Scott, for the alternative method of flooring and the great results.

I’ve seen indoor/outdoor carpeting glued to a studio floor, too. Don’t try it. There’s no question it will last awhile, but pulling it up is nearly impossible.

O.K. onto a related studio subject. What are you doing for jock chairs? I remember finding a wheeled stool that came with a lifetime warranty — but I’m not sure whose lifetime, because the third chair the office supplier had to replace was the last.

Finding a good sturdy chair that will withstand 24/7 use can be difficult. What’s your experience? (I can hear your reply now: “We don’t have an air chair anymore, the whole station is voice-tracked.”).

E-mail your thoughts to

johnbisset@myfairpoint.net

and remember that tips we use qualify for SBE Certification credit.

John Bisset has worked as a chief engineer and contract engineer for 39 years. He is international sales manager for Europe and Southern Africa for Nautel and a past recipient of SBE’s Educator of the Year Award. Reach him at

johnbisset@myfairpoint.net

. Faxed submissions can be sent to (603) 472-4944.

Submissions for this column are encouraged and qualify for SBE recertification credit.

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