Everything is Always More Difficult Than It Seems

Yesterday’s repair of my ICOM PS-125 power supply is a perfect example of the corollary to Murphy’s Law, “Everything is always more difficult than it first seems to be.”

A couple of weeks ago, the fan in my PS-125 started making a real racket. No big deal, I thought, the fan’s gone bad. I e-mailed Icom, and they tell me the part number is 2710000701, and it costs $13.40, plus tax and shipping. (The tax and shipping for this order turned out to be $8.64, which I thought was kind of high, but they did send it second-day FedEx.) The fan sat on my bench for the last week, but yesterday night, I got ambitious ambitious and decided to install it.

This is where the corollary to Murphy’s Law comes in. There are ten screws that hold the outer case to the power supply. I say “outer case” because when I got that off, I found that there was an inner shield around the entire supply.

Removing enough of that to get at the fan required the removal of 15 more screws. Once I got that off, replacing the fan was easy enough, but then I had to to button it all back up again.

My first thought was, “Boy, all this shielding is really overkill.” On second thought, however, I’m sure all that shielding is one reason why the power supply is so quiet. I have never heard any complaints about the PS-125 generating RF noise, something which cannot be said about other switching power supplies meant for ham radio use.

I also noted that there were some serious RF chokes on the AC input. These undoubtedly help prevent any noise from getting in or out via the AC line. So, while the repair was indeed more difficult than it originally appeared, it was worth the effort.

While the PS-125 has been “down,” I’ve been using the Astron 35A supply, and even though the PS-125 is now ready to go. I have that supply connected to a DC distribution strip that uses PowerPoles. When used this way, this supply can power both my IC-746PRO and the VHF/UHF rig and an accessory or two, and I don’t need multiple supplies on the bench.

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