Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

Keying Amp Without PTT

Larry Member ✭✭

Is there a way to use my Acom 1500 amplifier and the Flex 6400M while remote? Amplifier is a tube type so it would look something like this---- I would like the radio to key the amp without using the amp ptt. The amp would be set and tuned to a set frequency so no frequency or band changes would be needed. Basically, I would like to chat with a AM group down in my shop using the laptop and of course the radio and amp are located in the house.




  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    Yes, just hook up your Amplifier normally.

    You can disable Amp PTT in your TX Band settings. So that when you go to 80M it is active.

  • Larry
    Larry Member ✭✭

    Thanks Mike,

    Will need the amp to key when I click the mox button in the software.

    I remember the old CB amps I think were rf sensing to key the amp?

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator


    RCA cable from TX1 on radio to amp PTT in. Check the TX1 box in TX Band Settings table for each band where the amp will operate. Now when the radio goes into TX (MOX, PTT In, etc) TX1 out will key amp.

    A few precautionary things.

    • set radio maximum power out to the highest drive power you will need on any band. Protects against accidental overdrive of amp.
    • have a way to turn amp on & off remotely and operate/standby.
    • use a wattmeter that can be accessed remotely to verify power and SWR. Some meters can have the PTT line to amp looped through them to open amp PTT during high SWR conditions.


    Dave wo2x

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    CB Amps had RF sending keying lines since it was illegal to have an Amp on a CB radio and hence the reason there was no PTT keying line.

    What @David Decoons, wo2x says is absolute gold. At minimum I would get an Elecraft W2 watt meter or al LP100 watt meter that can break the PTT keying circuit for key SWR issues.

    What you want to do is a bit risky for a remote since you can't touch up the antenna tuning if required on the amplifier.

Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.