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.


  1. Dave, N8SBE says:

    Loose output terminals are common on Astron supplies. The normal reverse torque applied when folks remove cables tend to loosen them. The really nasty aspect is that the internal wiring that connects to the terminals inside the supply can rotate and short out.

    You’d think after all these years that Astron would re-engineer what is a poor mechanical situation, and potential fire hazard (yes, I know, they have foldback current limiting, but still, do you want to ‘test’ the crowbar mechanism in your supply that way?) Maybe it will take a recall to get their attention.

Speak Your Mind