Building and adding the KXAT1 automatic antenna tuner to the KX1

The final part of the upgrade to my Elecraft KX1 involved building and installing the internal antenna tuning unit.

The kit is remarkably small; it comes in one plastic zip up envelope together with a concise and well put together 12 page Assembly and Operating Instructions booklet. It also contains a note telling you who put the kit together, which is nice and reassuring. If anyone is willing to put there name to something, there must be good reason! Confidence that no parts are missing is my guess, and I think I’d be right because none were. This, of course, isn’t generally the case with electronic kits, as most builders would know.

The kit was very easy to build and align. The instructions are excellent and leave nothing to chance. I found winding the three coils and one transformer easy to do too.

Populating the PCB.

Populating the PCB.

As the KX1 is a small, compact piece of gear, the ATU needs to fit in without touching other components because if it does, the back of the enclosure won’t fit properly. This is one reason both sides of the PCB are used.

The yellow relays are on one side of the board while other components nestle underneath.

The yellow relays are on one side of the board while other components nestle underneath.

The only ‘snag’ I ran into (I always tend to make things more difficult for myself) was when it came to installing the mating male connectors. I misread the instruction to ensure they were fully seated before soldering. I read that to mean the black plastic bodies needed to be fully seated on their female counterparts. So I slid them down further until they did with a pair of long nose pliers. This presented problems when it came to ensuring the ATU’s PCB seated properly, so I returned them to their original positions, soldered them in and all went together well.

Fitting the ATU into the KX1.

Fitting the ATU into the KX1.

Alignment was easy to accomplish. All that was needed was a DDM and an insulated screwdriver.

Time to put it all back together again.

Time to put it all back together again.

The ATU worked perfectly first time. This is a wonderful addition to the KX1 that adds to its functionality.

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2 thoughts on “Building and adding the KXAT1 automatic antenna tuner to the KX1

  1. Your work area looks so orderly, I don’t see how you can get anything done! Seriously, could you post a list of the SWR values for L0, L1 etc you get when you through the troubleshooting as described in the KXAT1 manual on page 11 at the bottom under “If the relays are all working ….”

    Thanks and 73,

    Larry

    • Larry,
      I have carried out the procedure as mentioned on page 11 and got these readings on 40m:
      L0 = 1.0
      L1 = 1.3
      L2 = 2.2
      L3 = 4.8
      C0 = 3.1
      C1 = 3.0
      C2 = 2.8
      C3 = 2.9
      Trust this helps.

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