[Amps] rx noise?

[k7fm]

The 15 seconds of receiver noise during a contest is normal.  It is the 
ghost of Hiram Percy Maxim firing up the retary spark gap on 160 meters.

You may not be able to recreate it until the next contest, more likely in 
the middle of the night when you are at you are approaching your record 
score.  You should feel lucky that the amp did not send out blue smoke and 
shoot the meter glass across the room at 2 in the morning, just as your are 
nodding off.

73,  Colin  K7FM