Your browser is out-of-date!

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


A Pair of Hands in an Old Pill Bottle

Also in Workbench: How to best recycle collected junk

Chuck Lakaytis of Lakaytis Broadcast Service told me about a favorite adaptor that lives in a pill bottle.

Chuck learned this tip from a seasoned AT&T engineer who happened to visit while Chuck was trying to rack-mount some heavy equipment. In the shop, the engineer grabbed a couple of 2-1/2-inch-long rack screws and, using a hacksaw, cut off the heads. He then cut a slot in the end of each rack screw, deep enough for a straight-blade screwdriver to fit. This left him with a pair of headless rack screws that can serve as a temporary mount for your heavy equipment.

Here’s how it works: After you “locate” the equipment in the rack and note where the top two permanent rack screws will go, insert your “adaptor” screws into those holes. Then lift the equipment and hang it on the headless rack screws while you secure the bottom with regular rack screws. Then remove your temporary top screws and replace them with regular rack screws.

The PA911 and PA912, part of the ETS PA-910 series, can be used as an iPhone adapter. Courtesy Energy Transformation Systems To remove equipment, just do the reverse. Take out the regular rack screws from the two top holes and insert the headless screws; then remove the bottom screws. The equipment will “hang” on the temporary top screws until you remove it.

This extra set of hands makes racking equipment easier; you won’t need a second person to do the job. Store these little gems in a pill bottle so they’ll always be handy. Thanks, Chuck, for sharing an ingenious idea.

* * *

Repairing several classic Orban 4008 FM processors, frequent contributor Charles S. “Buc” Fitch identified a functional equivalent for the original and unidentified switch used in the “pilot on-off” and “operate-test” positions.

It’s C&K Part Number F2UEE, which is DigiKey part 401-1223. The matching push button cap in “red” is C&K Part Number F0203, which is DigiKey 401-1218 (

* * *

Belden’s Steve Lampen drew my attention to the simple circuit in my July 3 column (to adapt a balanced line microphone for iPhones). The one major problem Steve finds with the circuit is that it unbalances the mic. If there is any significant length of cable between the mic and the iPhone, this could be a major source of noise and interference (EMI and RFI). The solution is to maintain a balanced line, which will reject noise.

One way to avoid this problem is to buy the iPhone adaptor from ETS (Energy Transformation Systems) in Fremont, Calif. ( It’s part of their PA-910 series but contains the four-conductor plug mentioned in the column.

Inside the XLR is an actual balanced line transformer. This means that the mic and any cable between the mic and the adaptor are balanced. The transformer blocks DC, so you don’t need a blocking capacitor, and the resistance of the winding of the transformer is more than enough to load the iPhone input, so you don’t need the resistor either, when you use this adaptor.

Also in that column was a discussion about wires running in conduit. Steve points out those NEC guidelines suggest a maximum conduit fill of 40 percent. This permits cables to be added or removed, and makes the original bundle easier to pull. Did you know that the maximum fill inside a conduit is 40 percent? So how do you calculate the percentage of fill?

Belden offers a paper called “The Adventures of Conduit Phil,” which takes you through the calculations.

Steve is the multimedia technology and product line manager (entertainment products) for Belden.

* * *

I have found that many engineers don’t like to throw things away, and I admit to being a packrat to a point. But it would drive me crazy, as I made my way through contract stations years ago, to see engineers toss bad components in with the good ones. You’d have a drawer of parts, half of which were useless. This made a troubleshooting job that much more difficult, not knowing which part was good or bad.

Broadcast Engineer Paul Sagi has a solution: Turn the useless parts into refrigerator magnets.

Paul picks up tiny powerful magnets and a tube of super glue, attaching the magnet to the IC, or even several interesting components. It makes for some fun creations … unless you mind seeing reminders of past repairs every time you open the refrigerator.

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 44 years in the broadcasting industry and is still learning. He handles West Coast sales for the Telos Alliance. He is SBE Certified and is a past recipient of the SBE’s Educator of the Year Award.