[Elecraft] KX3 PTT Question

[Don Wilhelm]

Jim,

That RCA jack is KEYLINE OUT, and is intended for use if you are running 
an amplifier other than the KXPA100.  It will not work as PTT which is a 
different 'animal'.

The KX3 does have the GPIO signal in the ACC2 jack which can be set to 
operate as PTT in the KX3 menu - see the parameter settings for ACC2 IO 
in the menu listing on page 35 as well as the description on page 5.

So yes, you can wire a switch between the tip and shell of a 2.5mm 
stereo plug and set the ACC2 IO menu accordingly.

If you are using the KXPA100, that same GPIO signal is available on the 
3.5mm mono jack on the cable box - see item 9 on pages 14 and 15 of the 
KXPA100 manual.

Note that the ACC2 jack on the KX3 is a 2.5mm stereo type, while the 
jack on the KXPA100 cable box is 3.5mm mono (you can use a stereo plug 
with nothing connected to the ring).

Why the two jack sizes are different is a mystery to me.

73,
Don W3FPR


On 12/26/2016 3:18 PM, James Bennett wrote:
> I have a minor issue with my KX3 that has me scratching my head. Because of occasional background noise (XYL and two young boys) I seldom use VOX when on those rare occasions I venture to the SSB part of the bands. I’m using an inexpensive headset with a boom mic and there is no PTT switch on this unit. With VOX turned off, I know I can push the XMIT button on the KX3 to put the radio into transmit mode, and that works fine. But, I’d like to be able to lean back in my desk chair and carry on a conversation w/o having to lean forward to push that XMIT button every time I want to talk.  I thought there was a way to do this via a home brew PTT switch, connected across the tip and sleeve of the ACC2 plug. In fact, I thought that at one time long ago I WAS able to do this. But no longer.
>
> So, I tried another way - I connected the Elecraft-supplied RCA-RCA cable to the female RCA jack on the KX3-KXPA100 Adapter Cable and connected the shield and center conductor. Doesn’t seem to put the rig into “full” transmit mode. What happens is that the received signals on that frequency drop quite a bit in amplitude, almost to inaudible, but the red TX light on the KX3 does not light up.
>
> I’m guessing that I’ve accidentally changed something in the config settings, but I sure can’t determine what I did.