[Elecraft] 5 KHZ dead spots

[Merv Schweigert]

Have noticed this on other bands but paid no particular attention,
but today was tuning 160 meters and every 5 khz there is a pop
or change in background receiver noise when tuning. 
I listened carefully and it is there tuning up freq or down.  It is
at every 5 khz. 
I can hear it at 1809.1,  1814.1, 1819.1, 1824.1  etc.   sounds
like some older rigs that when you have the tuner engaged it
tunes every so often as you tune across the band.  Like a pop
or dead spot and as you pass the background noise changes a
little.  
No tuner installed so its not that.  Just curious if anyone hears it,
takes a quiet band but its there. 
Background noise is higher pitch on the low side, and lower pitch
on the high side of the "pop".  
Internal or external by some chance?
Merv KH7C