[Elecraft] key out
Geert Jan de Groot
pe1hzg at ymbk.nl
Mon Feb 20 05:37:35 EST 2023
(Including the list on this response - if discussions on email fraid are
fair game, then perhaps some Elecraft-related technical content is too)
> I am interested if anyone has a relay circuit design/suggestion to use
> the Key Out jack on the K3 to activate a light during TX?
> I have a few ideas but thought I would ask the masses.
The KEY output is spec'ed for 200VDC at 5A so with luck you should be able
to drive your load directly.
Wanting to protect the circuitry from grave natural forces, I have
successfully used a PNP power transistor to switch a load - emitter to
plus-power, resistor 4K7 between basis and emitter, second 4k7 resistor
between basis and KEY output, load between collector and ground.
If you're planning to switch some lights directly connected to the
electrical grid, then you may want to consider one of those
semiconductor relays - the KEY output will easily drive it and those
guys provide the isolation required.
The same circuit also works for the AUX outputs of the KPOD, though
those outputs are not as beefy (50V, 100mA).
Note that if you do use the KPOD AUX outputs, you may find the
documentation is wrong: in the connector pinout, AUX1 and AUX3 are
swapped. I don't know if the documentation has been corrected since I
reported this; it may save some head scratching knowing this.
Geert Jan
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