Topband: Strange Echo-LDE?...SDE?

[W9UCW at aol.com]

Yesterday morning from about  1030z to 1040z I was listening to Herb, KV4FZ 
call "CQJA" as he is wont to do at  about  his sunrise. Herb was particularly 
strong when I tuned on him, but I  noted that on each subsequent CQ he went 
down a couple "S" units. At his weakest  point I heard a signal seemingly start 
to answer him as he was still  finishing his routine. Listening more closely, I 
realized I was listening to a 3  to 5 second delayed "echo" of Herb, about 20 
to 30 hz removed from his  frequency. I sat mezmerized by the phenomenon and 
it happened again on his next  CQ. When he started the third time, the"echo" 
seemed to come on with a surge and  a quick shift of frequency....then settled 
in about 20 to 30 cycles away again.  The echo faded away in the middle of 
that routine and did not come  back.
 
Maybe I've been listening to  160 background noise waaaay too long.....do you 
think? It's been 50  years.
73 and best DX to all  topbanders, Barry, W9UCW