Icom IC-9700 Power overshoot

Damn you Icom. Again, and again, and again. Yes. Alse the IC-9700 is equipped with the famous ‘power overshoot’ or ‘ALC overshoot’ issue most modern Icom transceivers have. Apparently Icom can’t get a grip on this issue. Bad news for people using transistor based amplifiers (SSPA) in SSB mode.

Since the IC-9700 had a ‘TX PWR LIMIT’ function, setting this to 7%* will prevent the amp from going in protection mode. The bad side is that the amp only running about 50% of the effective power.

* In my case I’m using a Gemini 2-500 amp with 4W drive level requirement. If your amp needs 10W input, raising the 7% to [try something like 13%] the value you need. And no. 7% does not mean 7 Watts, thus overloading. The value (percentage) isn’t linear. Measuring the (avg) output will tell you.

Update: Setting the tx-delay to 20 ms solved the issue tripping the SSPA.


Skip to comment form

    • Steve G4HTZ on 17/04/2019 at 16:32
    • Reply

    I also use a IC-9700 with a Gemini 500 …and get no problem at all with tripping or overshoot ..mines set for 25w drive .

    Maybe worth changing the input attenuation on the Gemini .

    Several respected reviewers have stated there is not an overshoot problem on the 9700 .

    Good luck revolving the problem
    Steve G4HTZ

    1. Hi Steve,

      It’s worth trying, but I also have the problem on 23cm where the max 9700 output is 10 Watt and the input 8 Watts (tough limited).

        • Nigel G8IFN on 04/05/2019 at 10:45
        • Reply

        No problem with my IC-9700 and Gemini 23 cm amplifier. I have set the TX delay on the 9700 at 30mS.

    • Miguel Suñe Garcia on 13/05/2019 at 21:35
    • Reply

    On the 4th and 5th of May we worked the EA MAF test at 1.2 Ghz with the Gemini amplifier and 8 watts from the IC-9700, without problems for 6 hours on Saturday and 6 on Sunday, the “parrot” cq test was every 6 seconds and perfect without ploblemas.
    73 Mike, EA3TJ

  1. I Have no problems with that i use the Tajfun 1000 AMP and the problem was befor with my IC-7100 but
    the New 9700 does nothing like that….it works propperly.

    Best 73
    Peter DL6KA

    • David on 24/05/2019 at 14:13
    • Reply

    i have this with the 9100 and Beko 1KW amp, any suggestions?

    My Ic9100 was purchased in 2012.

    • Vernon on 21/06/2019 at 16:33
    • Reply

    I have a different problem, connected the IC-7900 to my Gemini 1.2 K linear which ran half power (15Watt input) until I switched the rig off. After switching the rig back on the display was dead and the TX/RX light came on. Cannot even do a factory reset on the rig.


    Vernon ZS6AIG

    • Andy Adams on 24/07/2019 at 12:20
    • Reply

    Hi David,

    I have a 9100 manufactured in 2018, with no ALC overshoot problems. Icom got to grips with the overshoot problem on the 9100. I know Icom modded the latter 9100’s, but do not know what they did. It would be worth contacting Icom and asking if it is a simple software mod? I run mine on 2m with a 3CX800 linear no problems throughout the range.

    73’s Andy GW0KZG

    • Tom on 03/10/2019 at 21:03
    • Reply

    You mentioned set ‘the tx delay to 20 ms’ – where is that menu option ?

    • Dave on 04/11/2019 at 12:19
    • Reply

    The Gemini VHF/UHF amps use a control board where you can reduce the TX change over delay to match the relay switching time.

    Unfortunately when built, the control board is not adjusted! My 4m Gemini 4 was had originally a 35mS change over time, the relays are specified at 20mS. By adjusting VR3 on the control board I was able to set the c/o to 21mS

    73 Dave G4AON

    • David on 13/11/2019 at 01:33
    • Reply

    thanks Andy- will look into this— for now, I use the BEKO 1KW with my old Yaesu 736R.
    I did hear that they fixed the issue in 2018, and now the radio is discontinued.

    David N2SLO

    • Rafael / NN3RP on 18/09/2020 at 20:09
    • Reply

    I had had Icom tech support fix the ALC overshot in the 7410 and 9100.

    I’ve just bought two new Icoms 9700 mainly for satellite / DStar and the 7300 (still to receive on Sunday) which will be setup with SPE 1.3k Amp

    • Mike on 14/01/2022 at 15:48
    • Reply

    I just ‘popped’ one side of my BLF188XR based 2 meter amp. Just in time for the January contest, of course… GRRRRR!

      • Tim Daniels on 18/07/2022 at 14:06
      • Reply

      If you haven’t already replaced the PA transistor, I would suggest looking at the newer ART1K6 transistor (available from RFMW in the UK). It is qualified up to 55V operation, but at 50V it is close to ‘drop in’ for the BLF188XR. With a higher breakdown voltage (which is usually the thing that kills the transistor when thermals are taken care of) it should give you a better ruggedness.

    • Gianni on 12/06/2022 at 09:16
    • Reply

    Hi at all,
    anyone have make any mods to receive on 143MHz to 144MHz to receive Graves Radar, it woul it very interesting.
    VY 73 de IW4ARD

Leave a Reply

Your email address will not be published.