Project engineer and consultant Tom Osenkowsky recently was called in to troubleshoot a Harris FM3.5K transmitter. It was off the air and multiple front-panel fault LEDs were illuminated. The numerous faults made no sense.
Tracing the path through the transmitter to the controller connections on terminal board E2, Tom found several intermittent contacts.
Fig. 1: The E2 terminal block in the FM3.5 transmitter is soldered to a board that interfaces to a ribbon connector jack.
Fig. 2: Closeup of the pins where they pass through the board and are soldered on the bottom.
Fig. 1 shows the E2 terminal block and the terminal board pins that solder to a board below the terminal block. A close-up of the intermittent solder contacts is shown in Fig. 2. Tom theorizes that because the block is in proximity to the blower motor, constant vibration may have caused the solder connections to become brittle and the pins intermittent. In any event, Tom replaced the block and the problem was solved.
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Cumulus Youngstown Market Chief Wes Boyd comes up with great tips and videos to share.
Fellow ham Tedd Mirgliotta, KB8NW, found a unique YouTube video that we’ll call, “No key?No problem!” He passed it on to Wes.
You’ll find the link at Radio World’s new links page for this issue. Go to radioworld.com/Mar-28-2012.
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Speaking of editors: Former Editor in Chief of Radio World International T. Carter Ross attended the annual meeting of the National Asphalt Pavement Association. He noticed something Workbench readers could use.
Fig. 3: A ‘Wet Paint’ sign keeps listeners away from your risers. Use the Radio World link to download and print your own signs.
The videographers found what seems to be a dead-simple solution to the problem of people climbing on a riser where a camera was positioned: Wet Paint signs.
This could keep people from trying to sit on your stage or risers at a remote, where talent and equipment might be in close proximity to a crowd. It’s a subtle yet effective way to discourage people from getting too close. It works best if the surface is clean enough to look like it was freshly painted. The videographer told Carter that if signs weren’t enough to discourage people, he had on occasion spilled a little water to add to the effect.
Carter included a link to a downloadable, printable “wet paint” PDF. We’ve saved it for you at the Radio World links page: radioworld.com/Mar-28-2012.
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It’s been a long time since I talked with John T. M. Lyles, an engineer at Los Alamos. John and I worked together at Delta Electronics; he then went on to design transmitters at Broadcast Electronics, prior to joining the Los Alamos Laboratory. John still stays in touch with broadcasting through the pages of Radio World.
In our Workbench article “Does Your Outpost Have the Basics,” we mentioned changing out foods you have in storage at remote sites.
John has found that Mountain House freeze-dried meals, sold at Wal-Mart and at many outdoors shops, are indispensable for camping or preparing for the unknown. They’re lightweight and require only a spoon and hot water.
Best of all, they have a long shelf life — over five years— and can be eaten from the pouch. They have a variety of selections, and are not like the old Meals Ready to Eat (MRE) that the military provides. They also have enough seasoning to be tasty. You can find the selection atwww.mountainhouse.com.
Need hot water? A small camping gas stove such as those made by Snow Peak or MSR can heat your stored water. Search Amazon. Remember to provide your future self a pot and lid too. If you’re going to be stuck at a site, you might as well have a good meal.
John wrapped up his note telling about his work completing the design and testing of a new pulsed RF amplifier prototype for Los Alamos. This will be used for particle accelerators. It is operating 24/7 at about 2 Megawatts peak power, and 200 kW average power. It’s in life testing right now, at 1,600 hours and running. The RF output is at 201 MHz, which is about the middle of the old TV Channel 11.
Production is next, followed by the installation of a pair of these beasts combined at each accelerator cavity over the next four years. They’ll install a pair each year. John works with a crew of engineers and techs that includes a couple of guys from Continental Electronics who joined him a few years ago. John’s hosted a number of visitors, too. It’s definitely the place to be for high-power RF!
Contribute to Workbench!You’ll help your fellow engineers, and qualify for SBE recertification credit. Send Workbench tips to johnpbisset@gmail.com. Fax to (603) 472-4944.
Author John Bisset has spent 43 years in the broadcasting industry, and is still learning! He is SBE Certified, and is a past recipient of the SBE’s Educator of the Year Award.
