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[Amps] ICOM IC-2KL will not UNkey on PTT

To:, Zehnsteine <>, Swen Röder <>, Charles Harpole <>
Subject: [Amps] ICOM IC-2KL will not UNkey on PTT
From: Charles Harpole <>
Date: Mon, 23 Mar 2015 18:23:34 +0700
List-post: <">>
I have two ICOM IC-2KL with matching power supplies and matching IC AT-500
automatic antenna tuners.

Connect one set to IC-718 for test, using rear acc. DIN socket correctly
patched to both IC-2KL and IC AT-500.

RCV works good and tuner senses band and tunes very good.

Turn on the 2KL "POWER" on and also OPERATE (panel label is "LINEAR"*) and
the xmit light turns on with no key-down and no RF from exciter.  If
key-down and provide driving RF, then amp puts out 500 watts.  But when
exciter goes to stand-by, the 2KL remains with xmit light on and will not
pass antenna back to the exciter.  Acts like part of a  PTT relay is stuck.

Turn 2KL to STANDBY* ("LINEAR"* sw off), and amp goes to pass receiving to
the exciter.

Thus, if I use the "LINEAR*" switch like a manual PTT, everything else
works great.

I am puzzled because when the LINEAR* switch is ON, the Transmit panel
light is on "trans," but with no RF drive, there is no output from the
amplifier until drive is applied.  Turn drive off and the amp remains in
that partial stand-by situation.

*The front panel has two switches  "POWER" and "LINEAR."  "POWER" is
stand-by and "LINEAR" is the same as an Operate switch.

Any suggestions?  Tnx, Charly

More info.........
-exciter to amp uses both PTT and ALC wires connected.
-disconnect PTT wire and no kind of PTT action happens in the amp.
-The IC-718 DIN acc. socket supplies PTT to the Aux. sockets on the amp and
ant tuner, but apparently in my set up, that does not function.  Is it a
broken wire?  VOM continuity shows all good.

Charly, HS0ZCW
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