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

[Dan Sherwood]

Don,

If I'm not mistaking, all the signalink does is use a relay to ground out
the PTT line voltage, much as a foot switch would do.  A logic high on the
PTT center pin would indicate a key up condition and should cause the rig to
return to receive state.

I could see where a flaky pull-up resistor could float the pin and cause
erratic behavior.

I yanked the PTT line, but the problem persisted.  I would think it would go
unconditionally to receive.  If it went high, it did not cause the rig to go
to receive.

The good news is I'm beginning to see the possible cause of the problem, and
it appears to be in the CAT rig control.  When I finally get CAT disable,
requiring a restart of FLDIGI, the problem seems to have mitigated.

Funny how you can run a configuration for 2 years and never have a problem,
until one day "poof"!  Perhaps the issue is software related after all.

73,
Dan



On 7/13/14, 8:43 PM, "Don Wilhelm" <w3fpr at embarqmail.com> wrote:

> 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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