[Elecraft] [K3] Curious about the whooshing

[William Evans]

Hello fellow Elecrafters.

I have a question about which my curiosity is just getting the best of  
me.  When I have the Sub Receiver on, linked, and all parameters the  
same between the two receivers, and I have the Balance control set in  
the middle, and then tune quickly across the band, sometimes it has a  
"whooshing" sound which makes it difficult to tune and listen.  As I  
slow down, the whoosh gets much less noticeable, but it is still there  
as the tonal quality seems to slowly shift from bass to treble.

I have 2.8kHz roofers in both receivers as well as AM filters in both.  
All filter frequency shifts are set to 0.0, but  I'm guessing that  
there is a slight phase difference between the two receivers  and when  
they are tuned, the time differential in both VCOs settling down  
varies enough to make a noticeable difference.  If I go to CONFIG:FLx   
FRQ and change the setting from 0.00 to 0.01, I can get the same  
effect without having to tune the two linked receivers.  Of if I  
simply listen in either LSB or USB for a long time on one frequency, I  
can hear the background hiss tone going from bass to treble and back  
again at a very slow rate (This is most noticeable when no signal is  
within the passband, but who, in their right mind would use a Ham  
Transceiver to monitor an empty frequency!-- ooops, I guess that would  
be me!)

Anyway, is my assumption about the phase difference between receivers  
a reasonable explanation, and/or is there anything I could do to  
eliminate the effect?  BTW, without an antenna (or the wrong antenna,  
e.g. an 80 Mtr Dipole on 20 Mtrs), I cannot perceive it, but with a  
resonate antenna, the phenomena appears.  I am using the same antenna  
on both receivers.

Am I far off base on my assumptions, or is there a simple explanation  
which I have not thought of yet?

Just Curious

W4ISH
Bill