[Skimmertalk] Images with Skimmer and Softrock VHF

[Mark n2qt]

I started using one of KB9YIGs VHF softrock ensemble radios
on 6M with skimmer.  I found that it had third order spurious
responses. (i.e. a strong station was spotted as being on 
several frequencies, and the spurious signals moved at three
times the rate of the desired).   This was at levels below the 
clipping point of the output opamps in the softrock.  There was
no improvement with changes to the audio input to the sound 
card.  Traditional image rejection looked good.  Changes in
sampling rate changed the location of the spurious images but 
did not eliminate them. 

This was using an Infrasonic Quartet soundcard under WinXP. 
What I found was changing to WDM from MME drivers cured the
problem. 

I'm posting this to see if there is a reason for this anomaly and
to hopefully save others from the problem.

Mark n2qt