Smit is the chief engineer for Salem Communications’ Twin Cities
stations in Minneapolis/St. Paul. He writes in with a really neat
tablet app called Idea Sketch.
Idea Sketch is a handy app from NoSleep Software.
many times have you needed to draw a simple diagram but didn’t have
a drawing program on your computer? Or you’re in the field with
your tablet or smartphone? Idea
Sketch is the answer.
can draw a concept or flow chart and convert it to a text outline, or
vice versa. The app lets you copy text in from another source such as
an email or document, import it and create an idea that can be viewed
as a diagram and outline.
out this slick YouTube video
showing what it can do. The application is available for both Apple
and Microsoft operating systems. The iOS version supports Box.com,
Dropbox and Facebook, among other features.
this is a great suggestion; thank you for providing it.
welcomes your own ideas for handy apps. Write to me at
our focus on AM maintenance items in the previous column, it is
timely that Crawford Broadcasting’s Cris Alexander recently
included a note in the company’s Local Oscillator newsletter
reminding the chief of every AM station to make certain that the
station’s occupied bandwidth measurements are up to date and in the
file. Remember, AM stations must do these measurements at least once
every 14 months.
while on the subject of paperwork, it’s a good time to make certain
that your quarterly tower light inspections are up to date too. Those
of you with MoM (Moment of Method) licenses need to keep an eye on
that two-year anniversary of the license grant. You will need to
recertify the sample system before that date.
engineers of nondirectional AMs can be lulled into a false sense of
security when it comes to logging practices. Don’t forget little
administrative things like this. Thanks, Cris, for the reminder.
Continuing our earlier
discussion about Optimod power supplies:
Broadcast engineer Paul
Sagi has worked on a number of them over the years. He offers an
alternative to a complete power supply change-out.
Fig. 2: A
typical switching power supply.
In Paul’s case, the
issues with these switch mode power supplies were shorted 0.1 nF caps
on the analog boards. (Once, an IC that converted between digital and
analog was bad.)
The Artesyn SMPS
pictured in Fig. 2 is the same or similar to several that Paul has
repaired, most recently in Gentner telephone hybrids. In those
supplies and seven or eight others, the problem was an open startup
resistor. Those resistors often are something like 110k ohms at 2 W
and are located near the main input filter capacitor. The 2 W size
makes them easy to spot. Replacement is inexpensive and fast. Just be
careful not to overheat the PCB traces when de-soldering or soldering
in the new resistor; they detach easily.
Over the years, Paul
has repaired at least 40 switch mode power supplies; though not an
expert, he has repaired enough to spot the problem quickly. Some use
a PWM control IC, number UC3842. It fails sometimes, and the 10 uF or
100 uF capacitor connected to them often fails, as does the startup
You can replace the IC
with a UC3842N or UC3842AN, as the original has a nasty habit of
Replacement capacitors in an SMPS must be low-ESR types. (ESR stands
for equivalent series resistance.) Capacitors are not pure
capacitance but have some value of resistance in series with the
usually have a lower ESR value than “wet” electrolytic
capacitors. Low ESR capacitors usually are more stable under varying
temperatures. Using traditional capacitors as a replacement may cause
the supply to overheat and fail. Thanks, Paul, for the information.
Fig. 3: Don’t let weeds eat your generator.
* * *
are gaining in popularity at both the transmitter site and studio.
It’s easy to forget these behemoths — until they stall or don’t
start in an emergency. Eliminate the surprise factor and budget a
checkup, especially when summer storm season is approaching.
a visual check inside the generator housing. Look for loose or worn
belts, bird (or other critter) nests at the air intake, leaking hoses
or fittings, and loose hardware.
up the genset is not the same as running it under load. You’re
fortunate if you have a generator, but make sure it runs as it would
when the utility power goes away. Routine testing and inspections are
crucial. It doesn’t matter what brand generator you have; if you
ignore it, the genset will fail.
to Workbench. You’ll help your fellow engineers and qualify for SBE
recertification credit. Send Workbench tips to email@example.com.
Fax to (603) 472-4944.
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