Dan Houg is station engineer for KAXE(FM)
in Grand Rapids and KBXE(FM) in Bagley/Bemidji, Mich. He wanted to add
temperature monitoring to his main KAXE transmitter; here’s how the project
He sought to avoid components made of
plastic because they could be melted in the stack exhaust. He located a Sunpro gauge
sender and capillary tube assembly made of metal at a local farm-and-fleet
store. Amazon also sells it, for under $25. Search for “Sunpro CP7975
Mechanical Water Temperature Gauge – Black.” Similar units can be found at any
auto supply store.
A benefit of this kind of sensor is
that you’re not working with small wire pieces or hardware above the tube
cavity opening on top of the transmitter.
With that in mind, and worried that
plastic zip ties might melt, Dan didn’t secure the sensor but just laid it on
top of the exhaust port of the transmitter, as seen in Fig. 1. The second photo
shows the sender cable coiled above the transmitter and connected to the
Fig. 1: The temperature
sensor is placed over the transmitter exhaust air grate.
Fig 2: The
interconnecting cable is coiled atop the transmitter and needs no plastic
Monitoring stack temperature while
tuning the transmitter is an excellent indicator of final efficiency. As the
tube’s efficiency lowers, an increase in temperature (heat) results, which can
be read off the temperature gauge. Put the meter right next to the output power
meter (Fig. 3) for convenience in making the correlation.
Dan added a Taylor thermometer powered
by a AAA cell (which he prefers to a “watch cell” because a AAA lasts several
years). He stuck the Taylor room thermometer to the equipment rack to monitor
the shack temperature.
Fig 3: You can easily
compare the correlation between temperature and transmitter efficiency by
locating the temperature meter near the transmitter PA meters.
Fig. 4: A
battery-operated Taylor thermometer monitors the transmitter shack temperature.
Dan writes that, just for grins, he
placed the Taylor sender unit over the tube exhaust for a few moments; but the
air temperature was higher than the 158 degree F limit for this particular
Taylor model. But again, any sort of plastic over the tube exhaust is asking
for a nasty meltdown. Stick with the automotive thermometer!
Dan Houg is relatively new to radio
engineering but comes from a background of tinkering with electronics and
The automotive water temperature
assembly is just one noteworthy item he’s added at the station. Another is an
inexpensive backup audio device he made using a Broadcast Tools Silence Monitor
III Plus and an industrial MP3 player that is activated on a contact closure
from the SM-III. Although there are commercial products that do the same thing,
Dan’s budget-saving approach has been useful during periods of automation hang-ups.
* * *
Broadcast engineering is a science that
runs on the laws of physics. But there are other laws governing the operation
of a radio station, and they are equally powerful.
Frank Grundstein, CBRE, CBNT, director
of sales for manufacturer Logitek (www.logitekaudio.com),
has gathered such laws through his years living on the Engineering Planet. Here
are a few:
on the back is only a few centimeters from a kick in the pants.
happens, it must be possible.
works better if you plug it in.
is impossible for the man who doesn’t have to do the work.
theory is better than its explanation.
amount of work done varies inversely with the amount of time spent in the
is ever a complete failure; it can always serve as a bad example.
first 90 percent of the project takes 90 percent of the time, and the last 10
percent takes the other 90 percent.
goes wrong at once.
obvious answer is always overlooked.
is always an easy answer to every problem: neat, plausible and wrong.
that begins well will end badly. (Note: The converse of this law is not true.)
facts do not conform to the theory, they must be disposed of.
has a scheme that will not work.
three correct guesses consecutively and you will establish yourself as an
probability of a given event occurring is inversely proportional to its
can find a way to wear out faster, it will.
project is not worth doing, it is not worth doing well.
more time you spend in reporting on what you are doing, the less time you have
to do anything. Stability is achieved when you spend all your time reporting on
the nothing you are doing.
every large problem is a small problem struggling to get out.
expectations yield negative results. Positive expectation yield negative
expands to fill the time available for its completion.
other line moves faster.
If you’d like your own copy of the
“Laws” to print out and post in your shop, email Frank Grundstein. Thanks, Frank, for sharing a
lighter (but so true) side to our profession.
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Author John Bisset has spent 43 years in the broadcasting industry and
is still learning. He works for Tieline Technology, is SBE certified and is a
past recipient of the SBE’s Educator of the Year Award.