[Elecraft] K3 won't unkey properly: Rear panel PTT

[Don Wilhelm]

Dan,

That sounds more like a Signalink problem than a K3 problem.
Please monitor the voltage on the PTT input from the Signalink to the K3.

If the voltage when transmission is to stop is in the range of 3 volts, 
that is the problem - that voltage is in the indeterminate range for the 
typical logic levels.
OTOH, if the PTT voltage from the Signalink goes reliably to 5 volts, 
then you have a K3 problem.

73,
Don W3FPR

On 7/13/2014 10:01 PM, Dan Sherwood wrote:
> I have discovered an issue with my K3, (ser 5820).
>
> When using my Tigertronics Signalink USB device, the unit keys the rig fine,
> but when the interface unkeys, transmission ceases, but red XMIT light stays
> on and reception is muted.  Like an indeterminate state.
>
> I did the following:
>
> Updated firmware ­ no difference.
>
> Unplugged Signalink rig cable to r/o a short ­ no difference.
>
> Ran a different digital program on laptop ­ no difference.
>
> The rig is configured to accept audio input from the line in jack on the
> rear when placed in DATA-A mode.  In SSB mode it accepts input from either
> the front panel or the rear MIC jack depeng on whether I am using a headset
> or the boom mic.  PTT is asserted through a foot switch via the front panel
> MIC jack.  This keys and UNKEYS normally.
>
> The Signalink assertes PTT through the PTT jack on the rear panel of the K3.
> It has an internal relay acting like VOX.
>
> When I use the signalink to key up in data mode, it works OK for a few
> cycles, then reverts to the indeterminate state.  Rig will not receive until
> I tap one of the keys mentioned below.
>
> To rule out RF feedback issues, I keyed the signalink in SSB mode, so
> line-in not selected,  Rig keys up but no power made, (signalink audio not
> selected).  Problem persists.
>
> Normal CW and SSB using foot switch PTT and either full or semi break in CW
> has no issues, even when driving an amp and lots of RF.
>
> CW through FLDIGI uses CAT keyup and release.  No issues there.  PSK uses
> PTT asserted through rear panel.  Issue seems with rear panel PTT only.
>
> Now here¹s the really strange thing:  When in this indeterminate muted
> state, if I tap band up or down, mode up or down, AFX, XIT, or RIT keys, the
> unit goes back to normal receive.  That initial tap DOES NOT perform the
> key¹s design function.  This is like a computer keyboard when a screensaver
> is running ­ the first keypress is ³swallowed² to wake up the screen, then
> subsequent keypresses work normally.  Any ideas here?
>
> Thanks,
>
> Dan Sherwood W6DAS
>
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