Saturday, September 14, 2019

Blended Ketchup

Which means catching up on a bunch of little things. 

First of all, the lightning damage story...which I started to call the neverending story, but I'm optimistic will end.  The most expensive piece of gear in my ham shack is a power (linear) amplifier made by the company that most of my radios are from, Icom.  That has not successfully turned on since the strike and mid-July was the last time it was on.  I have the service manual for this beast (it weighs 55 pounds, so shipping would be difficult and expensive), but I was hoping to bring it back to life enough so that I can turn it on and then troubleshoot it.  It might well be that the first part of that is all I need to do.

The starting point is that it smells like a power supply issue ("smells" in the metaphorical sense), and a power supply means analog electronics, which I have plenty of experience with.  If I get it started, then much of the rest is radio frequency electronics which is solidly my home turf.  It's only about twice the output power of the last HF avionics radio I worked on. 

The trouble is that there is virtually nothing published on the power supply.  There are no schematics in the service manual, just interconnection labels.  There are some schematics online, but no component values and no clues about how this blivet is put together.  The only information is hams helping each other online.  Besides that link, there's a hand drawn schematic for one part of it that another ham had trouble with, troubleshot and fixed. 

Armed with that little information, I disassembled the unit to the point I could pull the power supply module out, and started trying to find the problems with it.  Where the 240 VAC enters the unit, it goes through a little line filtering PWB that had two fuses on it.  Both of them were blown into another spacetime continuum.  Both fuses are 250V, 4A, an odd value but I was able to find the manufacturer's part number, and then find the fuses in several places.  Amazon had the best price, and I ordered many of them, anticipating having to replace them a few times as I proceed.  You can see the fuses in this picture - F2 and F1.

These are supposed to be your typical, clear, cylindrical, glass tubes with a thin, carefully calibrated wire in them.  Circuit wise (from what I can tell) those fuses are directly on 220 as it comes into the box, and after going through the fuses, the two lines go to a transformer.  A transformer for line frequencies represents a very large inductance to a lightning pulse, which can be thought of as being above 100kHz, and sometimes even above 10 MHz, based on its rise time.  I could envision scenarios in which the lightning surge dissipated in those fuses and circuits downstream would be OK. 

No joy, though.  The fuses didn't allow the unit to power on, although they didn't blow.  A little more investigation of the earliest routing of the power supply showed a couple of panel mounted circuit breakers on the the back of the amplifier.  One of those was blown open, the other seemed OK, but I ordered some of those, too, and will replace both.  I can tell that one side of the power line brought power into the box, but apparently not in a way that turned on the first stage of the power supply that generates 12V to allow it to be turned on remotely.  I think once I get that little supply to turn on, fixing things gets easier from there.

I never put my antennas back up after the dismounting that Dorian forced on me.  I moved the big HF antenna onto the back porch and stood the much smaller VHF antenna next to it.  Today, I pulled the VHF antenna into the shop to work on replacing the cable in a pleasant environment, and noticed an interesting damaged area on the cable. 

This is apparently where the cable jacket was touching the tower mast.  The area on the right of the opening appears to be melted and re-frozen copper.  The hole would be where some copper braid got blown out, or vaporized.  Because I don't see any abrasion on the (deteriorating) cable jacket, I think this is from the August 1 strike. 

I've gotten a replacement antenna rotator.  The control box was very thoroughly blown out, and the only meter check I can do of the outside unit showed it to be open, so that if I tried to rotate it with another controller, it wouldn't. 

Finally, when I'm not gathering information or buying parts for the radio shack repair, I am still working on my Webster internal combustion engine.  The flywheel has been in process since about the time of the lightning strike, when I gave up on the tool steel flywheel and bought a slice of cold rolled steel to turn into the flywheel.  I have been working on it an hour or so at a time when I get the chance.  

This will get three equally spaced 3/4" holes in that large, thin web between the inner hub and outer ring.  For that it moves from the lathe as pictured over to the rotary table on the big milling machine.  This will take about five times longer to set up than to do


  1. I like your description of the fuses!

    I've seen them with shattered glass, too. Might be worth looking into the "microwave oven" type fuses with a ceramic tube instead of glass. They also have very fine sand in them to fall into the arc and extinguish it.

    How old (and what type) of coax is that? The jacket looks pretty shot, even without the blown-out section. I was using Davis RF "Bury Flex", but lately I've gone to DX Engineering DX400E coax. They both have polyethylene jackets that holds up extremely well. I had some up in the sire in Torrance for 12 years, and reused it when I moved in with the YL in Long Beach, and it was up another 9 years. It still looks (and sweeps) "As New".

    Low loss, and extremely durable.

    1. How old (and what type) of coax is that?

      What type of cable is surprisingly hard to answer. There are no marks left on the jacket, and while I think it's Belden RG-213, I didn't leave myself a note. Likewise, I know I put up the antenna over Christmas break in 2003, but I'm not 100% sure that's the original jumper.

      I bought a length of direct burial RG-213 for its replacement, hoping that might endure the weather better.

  2. Have you sought out alternate supplies of metals in your area yet? Just wondering.

    1. I haven't done much, and haven't ordered anything since that flywheel. I'm working through metal I bought back last spring and (I think) have what I need to finish the engine I'm working on.

      There are many more companies saying they buy scrap than places that say they sell cutoffs or just sell metals.