FW: [Elecraft] K160RX Not Recognized by MCU

[Dan Barker]

There is never a negative rely voltage. That's why you don't see one. The
pin getting 0, and the pin getting 5v change.

Bob - AG5Q said it well a way a while ago:

"The outputs of U1 are programmed in push-pull. To program a particular
relay, its driver output is set to either a logic ONE or a logic ZERO,
depending on which way the current should flow, and all the other relay
drivers are programmed to the opposite state. All the current flows through
the designated relay and switches it, but this same current is divided among
the other relays and there isn't enough current through any one of them to
cause them to switch. After the relay is switched (in a few milliseconds),
all the driver outputs are set to the same logic state, so no current flows
through any of the relays."

Don't know if this helps, or what else to try, but I thought it may help. I
know those relays confused me at first!

Dan / WG4S / K2 #2456

<snip>
With the K160RX installed in the K2, I never see the negative going pulse to
toggle the K1 relay to the other state.
</snip>