[Elecraft] K2 Keying current?

[Don Wilhelm]

Chris,

The maximum keying current required by the K2 is limited by the 5 volt 
sourced by the MCU input and its pullup resistors.  There is a 220 ohm 
resistor in series with the signal line - so the maximum current will be 
23 ma.  Most any garden variety NPN transistor will do the job for you.

73,
Don W3FPR

Chris Kantarjiev wrote:
> I'd like to build a parallel port keying cable for my K2. Lots of schematics
> on the web, all calling for a 2N2222. I find that I don't have any of
> those in my junk box right now (horrors!) but have lots of 2N4124;
> the big difference is that the 4124 is limited to 200mA collector current.
> 
> It seems like this should be enough, since the keyer contact goes 
> straight to the MCU ... right?
> 
> 73 de chris K6DBG
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