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6400 with Palstar LA-1k amp

Anyone using the Palstar LA-1k amplifier with their Flex? Supposedly all thats needed is (naturally) the RF Coax and a PTT connection. I have a cable fromTX1 to the Palstar PTT and cannot key the amp. What am I missing?


  • Alan
    Alan Member ✭✭✭


    Make sure "TX1" is enabled for the bands you want to key the amp for. Go to Setings>>TX Band Settings.


  • KD0RC
    KD0RC Broomfield, COMember ✭✭✭

    Hi Jim, in addition to Alans response, you need to make sure that the RCA jacks are pulled either high or low, depending on your amp (Settings, Radio Setup). Most amps are keyed by bringing the key line low (Active Low), but best to check the documentation for your amp.


    Len, KD0RC

  • David Decoons, wo2x
    David Decoons, wo2x Member ✭✭✭

    @KD0RC the Active high/low are only for the TX interlock/Req connections. The TX1,2,3 outputs are always pulled low.


    Dave wo2x

  • Jim
    Jim Member ✭✭

    Well thanks for the comments, but no luck.

  • ka9ees
    ka9ees Member ✭✭

    Do you have anything connected to the PTT port?


    Ed KA9EES

  • Jim
    Jim Member ✭✭
    edited January 15

    I assume you mean the PTT port on the Flex. Yes.......... my Mic. And I have a RCA cable going from TX1 on the Flex to PTT on the LA1K

  • David Decoons, wo2x
    David Decoons, wo2x Member ✭✭✭

    Open a support ticket with Flex but here are some things to recheck.

    Make sure TX1 checked in TX Band settings for each band you want the amp to operate.

    Do you have an Ohm meter? Using the Ohms position unplug the RCA cable from the amp and check continuity between center and ground when the Flex is in transmit. You can also plug the cable in the amp and unplug the cable from the Flex. Shorting the center pin to the outer should put the amp into transmit.

    Double check all of your connections. Ensure you are plugged into TX1 on radio and PTT (not ALC) on amp.

    If you check and the radio TX1 line is getting pulled to ground on TX open a support ticket with PalStar.

  • W8TZ Ross
    W8TZ Ross Member ✭✭

    This is probably a **** question but is the amp in OPR mode?

  • Jim
    Jim Member ✭✭

    Yeah its in OPR mode. Thanks everyone............. I found the issue. I bought a brand new cable for the PTT connection between the 6400 and the LA1K and it turned out to be defective! Moral of the story........ take nothing for granted. All is well now. Thanks everyone for the help

    Jim KC3KRZ

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