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The KAT3A option is an internally mounted 100-watt automatic antenna tuner for the K3S and K3 transceivers.  With its installation, a 2nd Antenna jack is provided to select between 2 antennas.

We are now contacting customers who are on the KAT3A Waitlist.

Please place your order below.  If you no longer want to purchase a KAT3A, please click on the Cancel Order link in the KAT3A Waitlist email you received and provide your name on the form.  Informing us of your cancellation will make a KAT3A available to the next person on the waitlist.

Orders placed by customers not on the waitlist will be notified if extra KAT3As are available for purchase. 


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  • Overview
  • Specs
  • FAQ
  • Manuals 
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The KAT3A is completely controlled by the K3S.  Unlike most other internal automatic tuners, the KAT3A is capable of finding impedance matches for up to a 10:1 SWR.

The KAT3A provides a wide-range, switchable C-in/C-out L-network for matching a variety of antennas with SWR as high as 10:1 (100 W) or 20:1 (10 W). There are 8 inductors and 8 capacitors in the L-network, each switched with a DPDT relay for high reliability. The KAT3A also includes a second antenna jack and associated switching relay. There’s an additional jack on the board for routing the unused (non-transmit) antenna to the KRX3A  sub receiver module.



  • Maximum impedance match:  10:1 SWR
  • Maximum power handling:  110 watts

    Additional Features

    • 2nd antenna jack for Transmit/Receive, selectable from the K3S front panel
    • Per-band tuning memories held separate for both Antenna Port





    Q: If I am using an external tuner now, do I need to purchase the KAT3A tuner for my K3S?

    A: No.  You can continue to use your external tuner with the K3S.  The KAT3A, however, will provide more integration and automatic selection of the 2 antenna ports.


    Q: How hard is it to add the KAT3A to a K3 or K3S?

    A: You will need only basic hand tools (Philips head screwdriver, pliers) to install the KAT3A.  Like all of our K3S options, it will come with an installation manual that covers disassembly, installation and reassembly in a step-by-step procedure that anyone can follow.  There plenty of support from Elecraft along the way, too.



    KAT3A Quantity Price
    KAT3A KAT3A 100W ATU, Kit