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kat500 / kpa500 cabling

Mark Erbaugh
Mark Erbaugh Member
edited February 2020 in FLEX-6000 Signature Series
I'm considering a kat500 (auto tuner) and kpa500 (amp) from Elecraft for use with my Flex 6300. It looks like DDUTIL 3.0 will control both. How well does that work?  What is the process for auto tuning with this setup?  Is it a single button click or do I have to put the amp in standby, key the Flex with tune power (TUNE button in SSDR) and then activate the tuning sequence on the front pane of the auto-tuner, then stop the tune power from the Flex and take the amp out of standby? Is the tuning as seamless as using a K3 - KPA500 - KAT500 setup?

From the DDUTIL setup, it looks like the tuner and amp connect to separate COM ports. Do I need to connect a data cable between the two as you do when hooking them up to a K3?


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  • Steve W6SDM
    Steve W6SDM Member ✭✭
    edited February 2020
    The KPA500 and KAT500 are exactly the setup that I am using with my 6300.  My rig works like a 500 watt transceiver without the need to do anything between frequency/band changes.  When I change bands, I usually don't have to do anything. Sometimes when I change antennas I have to hit the tune button on the Flex.  I don't take the amp off line to tune.

    I have DDUtil and use it to monitor my rig temperature and power supply voltage.  It doesn't do anything with the amp.  Elecraft has a remote utility for both the amp and the tuner if you want to monitor and make on-screen adjustments with your mouse.

    The Elecraft manuals give you the setup and cabling scheme.  You need the cable that goes between the tuner an the amp, which I believe they sell separately.  Do yourself a favor and get some good RG8 or equivalent quality coax jumpers - it will help keep you from having RF issues.  I do not use the XCVR DB-15 connector on the KAT500.  I do use all the other connectors.

    I think the Electaft gear works fantastic with the Flex.  I put a lot of use into mine between contests and DXing.  If I won the lottery tomorrow, I would get an Alpha.  Until then, I couldn't be happier with the Elecraft amp and tuner.

    Hope that helps.

  • Mark Erbaugh
    Mark Erbaugh Member
    edited December 2014

    Thanks for the info "like a 500 watt transceiver" was what I wanted to hear <g>.

    Yes, I've seen the tuner-amp cable on the website. If I don't have one in my cables, Ill order one with.  Do you connect both the amp and the tuner to their own RS232 / USB port on the computer or just one (which?).

  • Steve W6SDM
    Steve W6SDM Member ✭✭
    edited December 2014
    Both of them hook up to the USB bus.  There is a 1/8 inch plug to USB cable for the tuner and a DB9/RS232 to USB cable for the amp. 

    If you don't already have one, it's a good idea to put a USB port card in your PC and plug directly into that.  Otherwise, if you don't have a card slot and need a bus, make sure you get one that requires its own power.  While I don't like adding wall worts to the shack for noise reasons, the bus extenders that give you extra ports and work off the PC's +5v will draw down the USB power and you will  start getting strange results on all of your USB devices because of the IR drop.

    I built both my amp and tuner from kits and they went together without any problem and worked as soon as I finished the testing.  My amp is wired for 230VAC.  I drive it with around 35 watts from the Flex, depending on the band, and it's very capable of putting out 600 watts, although I don't run it that high.  That goes to show that everything is designed well within tolerance for a 500 watt amp.

    I switch between three antennas, a tri-band yagi, a GAP voyager vertical, and a long wire.  The tuner gets along well with all of them.

  • dl9eri/oe9eri
    dl9eri/oe9eri Member
    edited December 2016
    To get the cabling with a flex 6k and the kpa500 right - you need an RS232 from a Com-Port of your PC to the kpa500 an 1:1 straight-throug cable to the PC-Port of the kpa500 - NOT the XCVR-Port ! - as is in some descriptions with Kenwood rig.

    This - and changing the baudrate to 38400 on the kpa500 on RS232P  -     Radio to Serial - Serial Poll to ON - will work with DDUTIL and show you the menu for remoting the amplifier.

    Had some hours here to find out because there is not much information to find for the direct control-setup and cabling with DDUTIL and KPA500 in the net.

    Now i can see and control the fan-speed, on-off-stby, voltage, amperes, temperature etc. - nice feature if DDUTIL is used - I mainly use it for CW over DAX IQ with Skimmer - and Flex CWX - that is the perfect QSK - Setup for Flex6K and KPA500 !

    Even if the KPA500 is switched to ON manualy you have to click the pwr-on button in DDutil to initialise the link - then you see all the parameters from the PA in DDutil.

    With this setup you can also use the Elecraft KPA500 Control-Software if you like.

    HAVE Fun !
  • Larry Benoit
    Larry Benoit Member ✭✭
    edited November 2018

    I control a KPA500 with DDUtil via a standard RS-232 serial connection. Use a standard serial cable with DB9 connectors (M/F) connected to a serial (COM) port on your PC.

    DDUtil supports band switching and mode switching plus display of all available operating parameters, such as SWR, PA voltage, Forward power, etc.   Amplifier band switching follows SmartSDR band selection, so you do not have to rely on the TUNE function to trigger auto band switching on the KPA500.  

    I've set up DDUTil for a friend to support a KPA500 and KAT500 and everything works as expected.

    You may have to modify and match the baud rate of your PC serial port with the KPA500 serial port. The default rate is 38,500 kbps on the KPA500.  

    FYI, I also control the KPA500 with DDUTil while operating REMOTE with OpenVPN over the internet (WAN), connecting directly to the KPA500 via an Ethernet to serial device server.  DDUtil is running on the remote PC and it communicates via a local virtual serial port created for the Ethernet to serial device server, eliminating the need for local PC to control the amplifier at the shack.


    Larry KB1VFU

  • Norm - W7CK
    Norm - W7CK Member ✭✭
    edited February 2017
    DDUtil also supports band switching on the KAT500.  When I change my TX slice to a different frequency, my KAT500 and KPA500 both follow it.

    DDUtil also lets you set the maximum power output of the Flex when the KPA500 is in OPER as apposed to in STBY.  I have mine set to 100w out when the KPA500 is in STBY and 22w out when in OPER.   22w gives me a bit over 500w output on the KPA500. This provides nice protection for the amplifier.

    You can control both the KPA and KAT from DDUtil.  I am also using the macro facility within DDUtil which allows you to create buttons with macros or series of macros behind them.  I place the KPA500 in STBY when I press the Tune button and then back into OPER when done.  Works slick.

    Its great being able to turn on/off both the KAT and KPA from within DDUtil.  Most of the functionality you need to operate both devices is available thru this single well thought out utility.

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