After a, gulp, 3-year hiatus, KX1 No. 2255 is back on the air!


Finally, the 30-80 mod is complete — just in time for Lobstercon.

It’s been a long time, too long, really, but I finally got a ’round tuit and used it to finish a project that adds two ham bands to my basic Elecraft KX1.

This was my first serious kit in decades. How many? Try the late 1970s, when I built Heathkit’s 2036A synthesized 2-meter FM transceiver and an HW-8 QRP radio, much modified since then. I still have both.

My initial KX1 build set the radio up to cover 40 and 20 meters. It worked perfectly right after button-up. One of my first contacts from the back deck and a simple wire antenna was PY7GK in Brazil. The contact was no cake walk. But we got it in the log.

After using the radio for several months, I figured it was time to add the final two bands. Well, that was three years ago, and the mod has been hanging fire ever since.

Why? All I can figure is a mild case of toroidophobia. It’s that malaise that can set it, even when one has successfully wound, tinned, and mounted the coils and transformers needed to get the basic radio operating in the first place.

Finally, with the summer of  ’13 fast approaching, I figured it was time to get off my duff. But, I admit, I took the easy way out. I bought a set of prewound toroids from Mychael Morohovich, AA3WF, a.k.a the toroid guy — a meticulous craftsman, I must say.

That purchase greased the skids for completing the modification. After tweaking the winding spacing a bit, I get 3 to 3.3 watts out on 4o and 20 meters. I get 4 watts on 80 and 30. One slight hitch: When I installed my autotuner board, the power output on nearly all bands dropped by a watt or two. I tend to use an outboard tuner anyway because it’s more flexible. But I don’t recall a similar power drop when I initially used the ATU on 40 and 20 meters.

I suspect that a relay on the ATU board impinges a bit on the windings of one of the filter-board toroids, changing the spacing and altering the output. So, for now the ATU is out of the case.

That said, the radio works!

As for toroidophobia, I’m building one of Doug Hendricks’s SOTA tuners. I’m winding those toroids myself using the chopstick approach I came across last year on the web. I’m still getting the hang of it, but it’s nice having that culinary tool as a third hand!

2 Responses to “After a, gulp, 3-year hiatus, KX1 No. 2255 is back on the air!”

  1. Great to read that you have the KX1 up and running. I had (sold last year) the KX1. It’s a great little rig and I had many nice QSO’s with it. I do recall the torod winding and the KX1 was my first kit as well. I used the chop stick method as well. I mentioned it on my K2 build blog as well as my QRP blog. I had a smile on my face when I read that you were spacing the windings and checking the output. I can remeber going at that for some time… just get a 1/2 watt gain or so. Well enjoy the rig and great to read you are back at the bench again with a Hendrick kit.

    • Oh yes, we tweak on. And I saved the two resistors included in the 30-80 mod for possible later modification. Swap out a couple of resistors on the board for those and the power comes up yet again. Elecraft included those for whom yet another extra half watt or so is important. All within the parts tolerances, I guess.

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