[Elecraft] K3- external keyer problems

[Don Wilhelm]

Brian,

At the KEY input to the K3, it is the low level voltage that is 
important, not the high level.  My guess is that your external keyer is 
not going to a low enough level to fully discharge the .001 capacitor 
that is on the key in line inside the K3.
Do your keyers have a resistor between the keying output line and the 
K3?  If so, that could cause slow keying.
It would be best to evaluate the low level during a string of dots with 
a DC input on an oscilloscope to see if the low level shifts after a 
couple dots.  If it does look for any cause of resistance (or added 
capacitance) between the keying driver and the K3 input.

73,
Don W3FPR

Brian Alsop wrote:
> Hi Keith,
>
> Unfortunately no bug.  
>
> Now that you mention it, it kind of sounds like a bug when one holds the 
> dit side down for a long time.   After a number of dots, each gets to 
> sound longer and longer and more slurred.
>
> For what it is worth,  the computer interface to KEY in uses an NPN 
> transistor.  The keyer uses a 2n7000 FET.  The FET on state has a really 
> low voltage drop.  K3  Key terminals have an open circuit voltage of 4.7 
> V (would have expected closer to 5).   The K3 displays a power-in 
> voltage of 13.7V.     Have removed all connections to the K3 but 
> earphones and KEY.   Problem does not go away.
>
> Wierd.
>
> 73 de Brian/K3KO
>   
>