A Solution for That Pesky iPhone Plug
Chestnut works at the Entercom cluster in Kansas City. He responded
to the May 22 Workbench column in which Michael Heim could not
find a source for 1/8-inch (3.5 mm) TRRS (tip-ring-ring-sleeve)
connectors used for adapting an external mic for use with an iPad or
Fig. 1: Mouser carries a Kobiconn brand TRRS connector fit for the
informs us that Mouser Electronics sells a Kobiconn brand TRRS
connector. Head to mouser.com and search for171-7435-EX.
He has found that the impedance at which many cell phones switch from
“headphone” mode to “headset” mode (to include a microphone)
is a bit higher. Therefore, he and his team have resorted to adding a
2.2k ohm resistor in series, as well as a 3.3 microfarad blocking cap
for safety. Kirk adds that the 3.3-microfarad blocking cap is Mouser
part number 647-UMW1V3R3MDD; it fits nicely in between the solder
cups of the XLR connector.
A schematic of the adaptor cable is shown in Fig. 2. Thanks, Kirk,
for a great solution, as more and more engineers press iPads and
iPhones into remote service.
* * *
David Sproul, chief engineer of WMAL(AM)/WRQX(FM) in Washington, said
he has enjoyed the Workbench discussions related to creating
fun graphics for engineering projects.
Dave reports that the ChartPak film we mentioned was temporarily out
of stock when he called, but he’s happy to wait. As for the
metallic film we discussed in March, there’s a dizzying selection
online. Be patient; I’ll get some specific URLs from Frank Hertel
for a future column.
I received a number of comments about using labeling films. Engineers
still find time to home-brew circuits, and they take pride in
labeling these projects professionally.
By the way, Dave Sproul passed a milestone in early June: He
celebrated his 40th anniversary with the stations. Congratulations,
Dave, and keep up the good work.
* * *
There must be something about 40th anniversaries.
For 40 years, Robert Gonsett, W6VR, has edited and published the CGC
Communicator. He recently announced it’s time for a sabbatical.
Engineers all over the United States have subscribed to this free
e-newsletter, but especially folks on the West Coast, where Bob is
The newsletter provided timely FCC news, inspection results and
useful engineering information to West Coast broadcasters. Readers
may remember seeing the CGC Communicator credited for a number of
Workbench tips over the years. For that information, we thank
It turns out the circuits used to upload the newsletter are being
dismantled by CGC’s Internet service provider “Connectnet.” So
until other arrangements can be made, the Communicator will take a
* * *
Paul Sagi, an engineer in Kuala Lumpur and a frequent Workbench
contributor, sends a link that may be ideal for small-station
management or even contract engineering firms.
WinWeb Online Office Suite is a cloud-based collection of business
apps. Included are accounting software, CRM, HelpDesk and business
planning tools. It’s ideal for start-ups or established businesses.
Google WinWeb Online Office.
* * *
Recently I ran into an engineer who was trying to feed cabling
through conduit and found it challenging. The same is true when
feeding cables through the coiled Nycoil sheathing used on a remote
Of course the easiest solution is to have the factory do it. But if
you’re replacing existing cable, here’s a solution.
Stretch the Nycoil sheathing out along a chain link fence, securing
the sheathing with wire ties to hold it straight. The next step is to
visit an electric supply house and purchase those little foam plugs
that have a string attached. A shop vac will suck the foam plug
through the sheath, when fitted with a reducer. A cardboard funnel
secured with duct tape makes a nice reducer. Next, tie your fish tape
onto the end of the string and pull the fish tape through. Tape your
coax and wires into a tight bundle, secured to the end of the fish
tape. Generously apply a gel wire lubricant, and pull.
The job is a little difficult getting started, but once it gets
going, you’ll be fine. Whether it’s the Nycoil or conduit,
remember to add a couple extra wires. There’s no way you’ll add
Contribute to Workbench. You’ll help your fellow engineers and
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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.