[Elecraft] DIGOUT1 to switch K3's key out to two separate amps based on band (HF or 6m)

[Don Wilhelm]

Jon,

I would use a 2N7000.  The circuit could be quite easy - a 10k resistor 
from +12 volts (K3 +12 volts out will do fine) - the source goes to 
ground - the drain connects to the relay coil.  I would strongly 
recommend a diode (1N400x) between the drain and ground (cathode toward 
the drain).  The other side of the relay connects to a voltage source 
that matches the relay coil rating (I would suggest a 12 volt relay just 
because it is easier).

If you use a SPDT relay, you can connect the common to the K3 KEYOUT and 
the NO and NC contacts each go to their own amplifier.

Set CONFIG menu DIGIOUT1 to OFF for all bands and antennas that you want 
the relay to be activated, and to ON for all bands and antennas that you 
do *not* activate the relay.  There are no "don't care" settings.

Because of the lack of "don't care" states, you may be better off 
decoding 6 meters from the band data outputs - a logical AND of BAND3 
and BAND1 will do because those two bits will only be active for 6 
meters (You don't have to set things correctly for the other bands).  
Follow a NAND with an inverter (another two input NAND with both inputs 
tied together) and that drives the 2N7000 - omit the resistor from the 
gate to +12 volts if you do it that way, the drain and source 
connections to the 2N7000 are unchanged.  A single CD4011 will do with 2 
gates left over and will operate on a 12 volt supply.

73,
Don W3FPR
 
73,
Don W3FPR

W7VH wrote:
> I'd like to use DIGOUT1
> to switch the K3's key out between two amps based on band
> (HF and 6m).  I'm not that technical and am not used to designing
> little  transistor switching circuits and wondered if you can give
> me some info on how to do it.  I guess I'd need a transistor that
> would switch based on the DIGOUT1 voltage and could handle the
> power needed to switch a reed relay to key the separate amps.
>
> If you have any info that could help, I'd appreciate it.
>
> Thanks,
>
> Jon
>