Im using an external 24 bit sound blaster (USB) @ 96k on one of the dell pc's in Alaska and not sure if its the PC or the card but it occasionally and annoyingly on PC reboot "moves" 20Hz or so (dang it) - so here I am looking at DCF39 and in fact its off the scale somewhere for a couple of days - that and Stefan may have been visible but I was looking/cal'd in the wrong place.
 
It apparently flips to one rate or another - checking up what it flipped to last time comes up with the same cal figure using Argo. Highly annoying but not being able to physically throttle the devices (electronically or physically!) Im a bit restrained. As an example in one state using Argo cal of 1000Hz the offset is 1003.2 and alternatively 1023.7 Hz    - Not sure if anyone else has seen a simliar issue but its annoying - it appears only to "flip" when the PC is booted.  At the moment its on spec and giving a nice daylight view of DCF39 or the 137.777 window - Ill move it down to 136.172 and HGA22 windows later
 
Laurence KL7UK  Alaska remotely operated from (freezing cold)  Oklahoma