Can’t Use TUNE Button on IC-7300 with KAT-500 Tuner

When I initially connected my IC-7300 to my Elecraft KAT-500 Antenna Tuner, I was unable to get the Tuner to start Tuning the KAT-500 from the TUNE button on the front panel. Here is what I discovered:

I was using separate 12 volt power from my Station power supply for the Tuner. Only the Tune Data connection was made from the AH-4 Tuner Connector to the KAT-500 (along with RF connections, of course). This seemed to work fine if I use the TUNE button on the KAT-500, but the IC-7300 behavior was as if it id not realize there was an external Tuner connected.

In discussions with several others about this, Fred WB4QOC suggested that maybe I need to use 12 volts from the IC-7300 for the Tuner power. It turns out that this solved my problem. I did that, and now the TUNE button on the IC-7300 acts as desired, tuning the KAT-500.

Why did this happen? My guess is that the IC-7300 must see current draw on the Tuner (AH-4) port 12-volt line, to know that an external Tuner is in use. Note that this is NOT the case with the IC-7600. I think I have heard that this is also NOT the case with the 7610, but have no experience there.

In the end, it all works great IC-7300, KAT-500 and KPA-500 Amp.



7 thoughts on “Can’t Use TUNE Button on IC-7300 with KAT-500 Tuner

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  1. Hi Tom –

    I’ve been reading your various blogs on the IC-7300/KPA500/KAT500 combination.

    I have been using an IC-7300 for about two years, and it has everything I need … except for a little more power.

    I currently use it with Icom’s AH-4 tuner (mounted in the attic) feeding an outside antenna … an Extended Double Zepp cut for 3.5 MHz (360 feet long) and center fed with 600 ohm true ladder line.

    This combination works very well on all bands 160 – 6 meters (it even tunes 630 meters …), but there are times I would like a bit more power. I like the idea of an amp that will be happy on 120vac, is relatively compact, and can be configured to provide the same auto tune functionality I love about the 7300/AH4.

    So the KPA/KAT500 seems to be the most logical solution (except for the price …).

    I’ve been in contact with Elecraft support on connections, so I feel your pain. There seems to be some inconsistency between recommendations and diagrams. But I have come to the same conclusions as you, and it looks like it should be clear sailing.

    All that being said, I am curious as to your final opinion of this set up.


    Lyn, WØLEN

    1. I stopped using the KPA/KAT-500 with the 7300. I plan to make it my Mobile/portable radio and now use the very small LDG Tuner that is made to mate with ICOM rigs. That has worked very well, including this weekend when I used the setup for a home generator-based Field Day operation.

      I have been using ny KAT/KPA-500 with my ICOM IC-7600. That has worked very well, with the one exception being that I fried a component in the 80m Bandpass filter on the RF Module. I was working a fairly high-SWR antenna at the time, but I am not really sure if that was the cause, or if it was just a component failure. This appears to be something that others have experienced too. The amp has been repaired, but I am doing some antenna and ground renovation before I hook it all together again.

      While I still like the integration of the KAT/KPA-500 with the ICOM rigs, I no longer believe that the protection circuitry in the KAT-500 will save the KPA-500 from damage, in the event of an antenna or feedline failure.


      1. Thanks for that, Tom Certainly something to consider, although I am still leaning toward that combo. Nothing else seems to offer comparable inter-operability with Icom auto tune rigs … and I really hate to give that up. With my existing set up, I am at 1.5:1 at any given frequency 160 – 6 meters. If the KAT-500 tunes as well as the AH-4, and the tuning sequence works properly, the risk should be minimal (aside from component failure, of course).

        Enjoying your blog. Keep up the good work!

        Lyn, WØLEN

    2. I am now revisiting my 7300 setup and wired it up with the KPA/KAT-500 again. Tested it all and it seems to be working fine. This is for Remote use when I am away from the shack. I am only using the Tuner at the moment, but will move to using higher power soon.

      Thanks for your comments about the AH-4 (here and on the 7300 email Group). I just ordered an AH-4 for Mobile use, particularly for the VA QSO Party. This sounds like a great flexible Tuner. When not using it in the Mobile, I will probably keep it at the base of one of my wire antennas at Home.


      Tom, KG3V

  2. Did you find a pinout diagram or a pre-made cable to connect the tuner power and key to the Icom 4-pin connector? I’m wiring my 7300 to the KPA/KAT-500 combo now.

    1. I purchased a commercially available (LDG) cable that connects that 4-pin connector to a Tuner, using 2 connectors, one for 12 VDC and the other for Tuning (TUNE input on the KAT-500). Here is the one I used:
      There are diagrams out there if you want to make one. I do not care to mess with Molex connectors.

      Good Luck and let us know how it works out

      Tom, KG3V

      1. Thank you very much! That’s exactly what I needed. Flames will soon be thrown, and clouds summarily warmed.

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