that ADF antenna scanning buzz is annoying. One of the expensive Japanese VHF
ADFs uses two receivers that are tuned in unison. One is used for silent ADFing
and the other gives you undistorted audio. If you fish you'll never regret the
ADF purchase. Its just a matter of time before you get a bearing on someone
acting just a little bit too bored in his radio conversation who is really
nailing em. You'll see. In commercial fishing they pay for themselves quickly.
Good thing about hooking it up to a scanner is that you can nail guys on
clandestine freqs as well as legal marine channels. The MURS frequencies
around 156 MHz are worth scanning as are the freqs right above and below the
two meter ham band. Scramblers might keep you from understanding a conversation
but it wont stop your ADF from getting a bearing. The only good simple anti ADF
technology was a tone superimposed (mixed audio) on you mic line that was the
same freq as the ADF antenna commutation frequency. It worked well against the
Regency Polaris ADFs but as other mfrs used different antenna switching rates
it was not universally effective.