Electronics Assembly Knowledge, Vision & Wisdom
Recurring Transmitter Failure - Disconnected Transcript
Recurring Transmitter Failure - Disconnected Transcript
A radio installation on a hilltop suddenly stopped working reliably. What was causing the transmitter to periodically fail?
Mysteries of Science

Dr. Gilleo
Mysteries of Science by Dr. Ken Gilleo
Dr. Gilleo is a chemist, inventor and general problem solver. Ken has been tracking industrial forensics and collecting case histories for decades. These cases are taken from the vast world of industry and commercial enterprise.

Check out Dr. Gilleo's eBook, 100 Mysteries Solved by Science. We hope you enjoy these case histories. You need not be an engineer or scientist to understand the problems and appreciate the solutions.
A large radio installation on a hilltop was used to dispatch trucks, equipment and personnel for an industrial site. The repeater was powered by batteries that were charged using solar panels.

The transceiver's final amplifier which boosts the power of the radio signal was replaced the previous year. Suddenly factory communications came to a halt. The receiver worked fine but there was zero power going to the antennae.

A few minutes later the transmitter started working again. After a few transmissions the output again dropped to zero. Five minutes later the transmitter worked again, but only for about thirty seconds.

What was causing the transmitter to periodically fail? Why would the transmitter suddenly start working but only for a short time?  

Here's the rest of the story.

Maybe it was Murphy's Law, or perhaps the higher voltage from the truck's alternator had blown the fuse. A new fuse did the trick and this time the unit kept running.

So while the symptoms were very similar, the causes where quite different.

Reader Comment

A customer with an IMTS mobile vehicular phone (a primitive forerunner of cellular phones) complained that the unit would go dead after about 30 seconds of transmitting, then would come back on in ten seconds or so.

I traced the problem to the main power connection, where a previous technician had replaced the recommend 7A fast-blow fuse with a 5A slow-blow. The transmitter current was evidently just enough to cause the slow-blow element to separate, and then to "heal" when it cooled down.

It took some time to convince the customer that the root cause of the problem was an intermittent fuse.

Michael Moran, CET
Reader Comment

Sounds like overheat in the PA stage. Someone most likely forgot to attach a fan connector or a cooling plate.

Robert Oppenheimer, LEP
Submit A Comment

Comments are reviewed prior to posting. Please avoid discussion of pricing or recommendations for specific products. You must include your full name to have your comments posted. We will not post your email address.

Your Name






Please type the number displayed into the box. If you receive an error, you may need to refresh the page and resubmit the information.

Related Programs
bullet Lightning Stikes in the Chemistry Lab
bullet Problems With Viscosity and the Moon
bullet Cloudy Copper Plating Bath
bullet Pay Clerk Production Woes
bullet Danger on the Adhesive Coating Line
bullet Innovative Impromptu Air Conditioning
bullet Epoxy Resin and the Red Gas Cloud
bullet Recurring Transmitter Failure - Disconnected Transcript
bullet Brighter Chrome on the Third Shift
bullet Mysterious Drop In Production Yield
More Related Programs
About | Advertising | Contact | Directory | Directory Search | Directory Submit | Privacy | Programs | Program Search | Sponsorship | Subscribe | Terms

Circuit Insight
6 Liberty Square #2040, Boston MA 02109 USA

Jeff Ferry, Publisher | Ken Cavallaro, Editor/Business Manager

Copyright © Circuitnet LLC. All rights reserved.
A Circuitnet Media Publication