Jeff Duntemann's Contrapositive Diary Rotating Header Image


I haven’t been darkening my own doorway here much over the last month. Part of it is an aversion to political posts. The left has made just about everything political in one dimension or another. Topics are not as common as they once were. It was also a quiet January with (thankfully) few crises to report. We spent a considerable amount of time getting ready for The Big Backyard Overhaul, which begins tomorrow. I’ll take some photos and vids of the demolition of our waterfall and our pool, which is having its deep end removed. The waterfall was nothing special: a jumble of mini-boulders in an aggregate of mortar. It looked like somebody dumped a few tons of granite in a pile and then just slopped mortar into the cracks. The boulder pile is there to prevent people from installing a diving board. At least for us, they needn’t have worried. I did all the diving I think I ever want to do in college swim class.

K7JPD is creeping back toward the air so slowly that I’d characterize it as being under the air rather than on the air. I’m still researching compact antennas. In the meantime, I’m going to run a 60-70′ longwire to one of our tall palms, and match it with my Icom AH-3 tuner. I have two very good Icom radios: an IC-729 purchased in 1991, and an IC-736, purchased in 1995. The IC-729 is an odd bird: It was designed to be a mobile HF rig, and it runs off 12VDC. Alas, although smaller than your typical HF rig, I couldn’t conveniently fit it into our minivan, so I built a 30 amp 12V supply and used it on my bench until I bought the 736. Since the 736 arrived, the 729 came out of the box only once a year, for Field Day. I assume it still works, and I’ll find out soon, if not as soon as I had hoped.

The AH-3 is a great tuner. I used it at our North Scottsdale location in the 90s, feeding a 180′ longwire out to the corner of our 2.5 acres. I had a crappy ground there and so the longwire didn’t do as well as other, shorter longwires I’ve had in the past. I really hope the AH-3 still works, because if it doesn’t, there’s a problem: The 729 and the 736 can’t connect to Icom’s newer autotuners. I have a solid manual tuner, but the way the AH3 sits there and clunks around for a few seconds assembling a match when you push the Tune button is borderline uncanny. I suppose I could get a newer radio, but newer radios are basically computers. I stare at computer screens all day. When I operate a radio, I want to handle actual dials, switches and knobs.

Switches, yes. There’s a parallel project to getting my radios back on the air here. I’m building a 12VDC system to power the IC-729, 12VDC LED light strips in the shack, and a few other things that work on 12V. The ultimate goal is to have something like a Goal Zero Yeti backup power unit, on trickle charge from the wall until I can put it on trickle charge from a couple of solar panels. In the meantime, the system will be powered by the 30 amp supply I built for the IC-729 in 1991.

The project involves a DC power control and distribution panel. I’m using PowerWerx fittings and Anderson Powerpole connectors. I’ve never used Powerpoles before. Nothing difficult about them, but it’s a new skill.

And then there’s the AH-3 tuner control cable problem. The tuner came with 16′ 4″ of control cable, and that’s not quite enough to get down off the roof of the shack and into the building far enough to reach the radios. So I have to work up an extension cable in Molex connectors and 4-conductor thermostat wire. I did a little bit of Molex work way back when I was a Xerox tech rep, but that was 40-odd years ago and I’m rusty. So I bought 15′ of 4-conductor thermostat wire at Ace, and ordered something I didn’t think was a thing: a kit of three pairs 4-pin Molex blocks and enough pins/sockets to fill them. I have a crimper, and when I get this posted I’m going out to the garage to make a 15′ extension cable.

A set of four glass dogbone insulators arrived a few days ago, and I have plenty of #18 copper wire. Nothing gets strung, however, until I see what sort of heavy equipment will be hacking up the backyard tomorrow and days following. There’s still plenty of room for things to go wrong, but with a little luck I should have the station back on the air by next weekend.

I get asked “How’s QBit doing?” a lot, and the answer is simply this: miraculously well. He was supposed to be dead five months ago, and yesterday he was still galloping around the backyard with the rest of the Pack while we played dog soccer. Carol has been keeping an eye on his lymph nodes, which seem to be back to their normal size. His appetite is certainly good, and while deaf, he’s otherwise in pretty decent shape for a dog who will be 14 this coming Friday. We don’t know how he beat cancer, if indeed he did beat it. We have our suspicions: Carol custom-makes dog food for all four of them out of ground beef or ground turkey, and vegetables. QBit likes it so much that I think he just told himself, “Like hell I’m going to die, if she’ll give me another bowl of this tomorrow morning!”

He’s just stubborn that way. Wonder who he learned that from.


  1. Great to hear that you’re getting the radios set up. I remember you were talking about putting in a decent ground rod last year.

    I’ve been doing a lot of work with SDRs for HF & VHF recently, including some DIY designs. One thing I’ve found is that I can build some pretty sensitive receiver front ends but the combination of poor antennas & grounding plus local noise here in the southeast end of the Phoenix Metro area seems to render them all about the same. I really need to work on my antenna situation.

  2. Tom Roderick says:

    Jeff, it sounds like you have been out of HF radio longer than I was before I got back into it in 2015. These days I think EVERY HF rig I have seen takes 12 (actually 13.8) volts DC as power — source of which is left as an exercise for the purchaser. There are a number of good RF sensing autotuners out there now. I bought an SGC-239 that I put in a waterproof box outside and have been using since 2015 with no issues. It has tuned my dipole on all bands from 80 meters through 6 even though it is not rated for 6. It is cheap simple and has worked for me. A lot of good info at their web site. YMMV

    1. I have two power supplies capable of putting out 13.8VDC, the one I built (which can be adjusted a volt or so in either direction with a trimpot) and another I bought from SK K7KR’s estate. I don’t know that I’m ready to retire the IC-736 yet, but it’s good to know that their newer HF rigs will take 13.8VDC.

      I bought a custom entry box from Chris Perri K7FP. They’re expensive, but gorgeous, and saved me a huge amount of messy metalwork, which I might have enjoyed doing if I weren’t 18 months past schedule finishing Dreamhealer. See There’s a solid copper ground plane inside the box, with four high-tech lightning arrestors, two with UHF fittings, and two with N fittings. The box has eight 1″ holes punched in the bottom face, and came with grommets and plugs for all eight. I’ll write the whole thing up with pictures when I have something functional.

      1. Tom Roderick says:

        Looking forward to the pictures when you get finished. Most of my projects take longer than I estimated. I solved that by not estimating time any more. It will be finished when it is finished!
        Thanks for the tip on K7FP. I had not found him before, but I will keep it for the future. It is really outstanding. Don’t worry too much about missing HF right now Jeff. Get your book finished then maybe we will be getting some sun spots back!
        73, Tom

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