[Spooks] Whale signal ii up on 8707.3

[Utility World (Hugh Stegman)]

"Whales" always seem to appear on or near US military frequencies.  It's
some kind of open-circuit noise.  When someone talks, the sound stops.  When
the freq is quiet, the sound builds gradually, like the gain opening back
up.

Possibilities (in order of likelihood):

Oscillation in a ringy circuit with a lot of gain
Seeking LINCOMPREX pilot tone
RF feedback

-hugh