[Elecraft] KNB2 - How can I tell if it is working?

[Stuart Rohre]

One can wire up a junk box relay to pull in from a normally closed contact
carrying its coil current.  When it pulls in, it breaks the coil current and
there will be an arc at the contact, and the process will repeat when the
spring restores the contact.  Put  the arcing contact near a wire to antenna
input of the K2, it will pick up fine.

You can wire up a single pole relay, or half of a double pole.  You can use
the double throw types, and wire the power thru the closed contact, while
relay is idle.  This is the standard noise maker Ten Tec uses to test rig
noise blankers.
72,
Stuart K5KVH