[Elecraft] K3 transmit/amplifier relay

[Joe Subich, W4TV]

 > KEY OUT in CW mode is the logical or of straight key, internal
 > keyer and PTT.  Turning on VOX neither asserts nor gates KEY OUT

No, when any of the (input) signals I named - straight key, internal
keyer CW, PTT or VOX (note VOX is an input *not* a control state) -
is active, Key Out is closed (low impedance to common).  That is a
logical-or (more specifically logical-NOR since it is a low going
signal).  It would properly be written:
   NOT (Straight Key OR Internal Keyer OR PTT OR VOX)

What you want is for PTT (input), VOX (input) or QSK (control state)
to gate the Key and Keyer.  In other words, written as:
   NOT (((Straight Key OR Internal Keyer) AND (PTT OR VOX)) OR
       (PTT OR VOX OR QSK))

73,

    ... Joe, W4TV

On 3/14/2011 3:59 PM, Guy Olinger K2AV wrote:
> On Mon, Mar 14, 2011 at 3:01 PM, Joe Subich, W4TV<lists at subich.com>  wrote:
>
> Key Out is the logical or of the key input
>> (straight key, internal keyer, PTT and VOX).
>>
>
> WRONG. To use your terms and convention, as currently coded in firmware...
>
> KEY OUT in CW mode is the logical or of straight key, internal keyer and
> PTT.  Turning on VOX neither asserts nor gates KEY OUT
>
> To prove that, place in CW mode, and hit the key or the paddle with VOX off
> and PTT not asserted. If your amp is connected, out of standby, and uses KEY
> OUT, it will change state with the CW.
>
> This *IS* a FIRMWARE directed behavior.  It is not implicit in physical
> circuitry anywhere.  The requested behavior change does not require a
> hardware change, even though the KEY OUT jack is a hard conversion of 7R
> from zero state to high voltage short at KEY OUT.
>
> When in CW mode, with neither VOX nor PTT asserted, leave the K3 in receive
> mode, use straight or internal keyer assertion to place monitor audio on the
> three RX audio DAC's only. This is entirely a firmware change, though
> possibly an ugly one.
>
> 73, Guy.
>