[Elecraft] K3 Amplifier Keying

[Don Wilhelm]

Phil,

While it is likely the K3 KEYOUT can handle that with no problem, I 
would not try to just 'tie them together'.
Reason, the open circuit voltage for each amp may be different, and that 
will cause current to flow from one amp to another.
I would suggest using either a switch (hard to remember to change it) or 
make up a "multi-keying" circuit that is driven by the K3 and provides 3 
isolated keying outputs.  An inversion stage with a pullup resistor on 
the input followed by 3 HEXFETs (like the IRF830 or IRL620), each 
driving a separate amplifier would provide all the isolation needed, 
along with plenty of resurve current handling capacity for most any 
amplifier which uses a positive keying voltage.  One could also drive 
such a circuit from the KEYOUT-LP from the ACC connector (max of 10ma 
current sink) and use the K3 KEYOUT  to key yet another amplifier.

73,
Don W3FPR

Phil LaMarche wrote:
> My K3 will be keying 3 amplifiers....144...50 and HF.  I have two amp keyers
> that can be used or just one.  Should I find an RCA cable with 3 females and
> one mail or does anyone have a better suggestion.
>  
> Thanks
>  
> Phil
>  
>
> Philip LaMarche 
> LaMarche Enterprises, Inc.
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