Taking some of my own medicine


I took a dose of my own medicine and performed a little preventive maintenance on my Astron RS-35M power supply.

Last week, I wrote a blog post on preventive maintenance for one of my writing clients.

Afterwards, I decided to take some of my own medicine and do a little preventive maintenance around the shack. I started with the Astron RS-35M, which provides the DC power that runs HF transceiver and my VHF/UHF transceiver in my shack. I had started noticing a few little things, such as the voltage adjustment being a little fussy, that I wanted to correct before the supply failed on me.

After removing the cover, I vacuumed all the dust out of the supply. The RS-35M wasn’t very dirty, but even so, getting the dirt out of a piece of equipment is probably the first thing you’ll want to do when performing preventive maintenance. Dirt impedes air flow. That can lead to higher operating temperatures, and as the lab manager that I interviewed for my blog post said, “Heat kills.”

Not only should you vacuum any dust out of a cabinet, you should also clean the fan filters, if your gear has them. Dusty filters prevent air from flowing smoothly through equipment, and that means the fans don’t cool as well as they should.

Once that was done, I did a visual inspection. One thing that you want to look for are components that look like they’re getting too hot. Another thing to look for is evidence of arcing. Whatever is causing the overheating or arcing will eventually cause a unit to fail. Fortunately, I found neither.

Next, I checked to see that the components mounted to the enclosure were securely screwed down. In the RS-35M, the transformer, the bridge rectifier, and an electrolytic are mounted to the enclosure. Oddly enough, the bridge rectifier was quite loose, so I tightened it down. Also loose were the output terminals. I tightened these down as well.

Finally, I squirted a little cleaner and lube into the voltage adjustment pot and worked it back and forth. That seemed to do the job. That pot now works smoothly and cleanly.

I put the cover back on, reconnected the power cable, and got back to making QSOs. It should be good for another couple of years.

Getting Your Gear to Play Together Nicely

On EETimes.Com, Steve, KE8FP, writes about helping his father, K8TL, get his satellite and moonbounce gear playing together nicely.  I knew this was going to be a good story when he quoted his father as say, “Son, it’s time to pay for some of that college education!”

Some of the comment are great, too. Read the entire story here.

The Littlest Things Matter

Flakey Omni VII power connector

Sorry for the poor photo. I'm not a great photographer. You can see, however, that the high-resistance connection got so hot that it melted and charred the crummy nylon connector.

Yesterday, down at the museum, our TenTec Omni VII started acting flakey. Twice, while Ovide, K8EV, was talking to a guy in Poland, the radio seemed to reset itself. He checked all the connections, but couldn’t find anything obviously loose, and after he signed off, we played around with the radio a little, and nothing weird happened, so we thought nothing more of this.

Today, however, after firing up the rig and calling CQ a few times, the radio just shut itself down. This time, Jim, K8ELR, and I disconnected pretty much all of the cables to the radio and found the problem. See the image at right.

As it turns out, the problem is the crummy nylon power connector TenTec used on the power cord. It looks like it didn’t fit tightly, and after jiggling around back there, for the last year or so, the positive connection turned into a high-resistance connection. So high, in fact, that the heat generated by the high resistance charred and melted the nylon around the pin. A little thing like a nylon connector is responsible for taking down a $3,000 rig.

I’ve sent TenTec an e-mail, asking for suggestions on what I should do now.  I’d like to replace the crummy nylon connectors with PowerPoles, but I’m not sure where to find a PC-mounted PowerPole connector, nor do I know if it will fit in the holes in the Omni VII’s PC board.  It looks like it might, but I’m not sure.

If any of you know where to find PC-mounted PowerPole connectors, please let me know.