Sunday, September 19, 2021


 I was reading some stuff on the internet this morning when my phone chirped to let me know that my friend Bob W3BBO was on the air calling CQ. I saw that he was on 30 Meters, and I thought the band might be conducive to a Pittsburgh to Central Jersey QSO, so I ran downstairs to fire up the KX3. I flipped the switch on my Astron 20 Amp power supply and there was no hum and the rocker switch didn't light up.

Not good.

I checked to make sure the power strip that I have it plugged into was working and that showed to be fine. My Astron 7 Amp power supply is plugged into the same surge protector and it fired up just fine. I replaced the fuse and powered up again. This time, there was a hum and the rocker switch lit up - all for about a second. Then the new fuse blew.

I unplugged it, took off the cover and gave it a visual inspection. Nothing burnt, nothing charred, no funny smells. I then took a meter to all the major semiconductors - pass transistors, diodes and SCR and the readings were normal - no shorts. The filter caps look ok - from my experience with repairing studio strobes, those big electrolytics tend to bulge a bit before they have a "non passive failure" so I doubt they're the problem. That leaves the transformer itself or something on the voltage regulator board. I'm thinking the voltage regulator board as transformers in and of themselves really don't go bad without some evidence of getting overly hot or burning.

I don't have the time or resources to go into deep trouble shooting right now, so I'll rely on the 7 Amp supply for the time being - too many projects, too many things to do. Besides, running 5 Watts shouldn't even make it raise a sweat. While I was down there, after getting things transferred over and squared away, I made a couple contacts on 15 Meters with some Texas QSO Party stations. I also had a brief QSO with Lazlo HA3NA on 17 Meters (and I got a 579)!  It was really nice to see 15 and 17 Meters alive for a change. Maybe the sun spots ARE making a comeback.

When I do get the time, there are some wonderful resources on the web for fixing these babies. One in particular can be found here -

It's a nice step by step resource and as it's been over 14 years since I repaired circuit boards down to the component level every day for a living, my trouble shooting skills are a bit rusty to put it mildly. I'll take whatever help I can get.

On another note, I downloaded Hamrs onto my cell phone after watching Tom K4SWL use it on his POTA videos. It's a super easy logging program to use, even easier than Ham Log NG. I like that you can create specific logbooks for individual POTA activations or other events. Each log can be converted to an ADIF so that I can import them into my master AC Log logbook on the laptop. I also downloaded it onto my Android tablet which should be a bit easier on my fat fingers in the field. This, of course, assumes that I will give up on paper and pencil. That may be easier said than done! LOL!

72 de Larry W2LJ

QRP - When you care to send the very least!


  1. Tnx for the interesting Astron troubleshooting document. You really should read "B.2" for starters. Hope the problem with your PS isn't that serious. I have a Astron 50 Amp myself and so far no problems. But as these things get older I expect problems in the future. Nothing electronically will last forever! Good luck! 73, Bas

  2. Good morning Larry, I had the same issue with my RS20M just a few years ago when using my Icom 7610. In a nutshell, I found that the RS20M is rated at 16 continuous amps. After running 100 watts with the 7610 the current draw was around 18 amps. It was just enough of a draw to keep the supply working, but over time the bridge rectifier gave out. I did repair the supply, and it's a spare now for QRP work. I upgraded to an RS30 power supply, which has been working great. I have included the blog post links below

    w regarding my journey of repairing the supply. Here are some links I hope you find useful.

    Keep us posted with how the repairs go.

  3. My Astron 20m has led a rough life considering its rated for 16 amps. During 20 years of abuse its had filter cap, and pass transistors replaced. Still in use AG4P

  4. Thanks guys! I repaired this once before, many moons ago. Last time it was a pass transistor. They read fine on a meter, but that doesn't mean one can't be breaking down under voltage. I've been using this supply strictly QRP since about 2003, so I definitely haven't over stressed it recently. Just need time ..... precious time! de W2LJ