There is a bit of a challenge doing what you have defined.

The PA output of your VHF radio is an analog (voice) format intended to
drive a speaker. Either an AC or DC relay would respond to the audio peaks
but not provide a contact closure of much length so the horn would only have
erratic short beeps. A somewhat complex circuit could be developed, but in
my opinion this is not a practical application.

Don Dando


"16sail" wrote in message
...
I'd like to wire the PA horn output from a VHF to a trigger a
tradition non-PA horn. I would think that I could use a relay for
this but could use some guidance with respect to selecting and wiring
the right relay here.