To Bob Laney

> I am experiencing a problem of not getting WWV time messages using SDR.
 I have installed a 75 MHz Packard Bell computer, which is Y2K compliant, to 
 replace a 386 16 MHz computer that I had been using to record 2 sensors 
using 
 SDR.  The old computer's clock will revert to 1980 come this Friday night....

    Could you just stay up till midnight and then tell the old computer that 
it is now Saturday 1st January 2000?

> I put the A/D board back into the old computer and the WWV messages came 
though and the system locked, so the board is OK.
   
    So with the old computer running, there is no problem. If you now also 
switch on the new computer nearby, what happens?

 >I use a digital short-wave radio for the WWV signal ...there seemed to be a 
little more RFI hash from the Packard Bell computer than the 386, but when 
the WWV signal was 
 strong it overrode the RFI.
    
    To your ear it may have done, but did you check it on a 'scope? The 
faster the computer, the more likely it is to generate RFI. WWV broadcasts on 
2.5, 5, 10, 15, 20 & 25 MHz. Which are you on and have you tried another 
frequency?

> WWV is grounded through pin 9 on the connector. I notice that pin 37 is 
recommended, but I have used the 386 for more than 2 years with pin 9 as the 
WWV ground and it worked well.  Because it's the same A/D board I would guess 
this would not present a problem.
 
    You know that you have a problem, so don't assume anything. There are 
digital line grounds, analogue line grounds, grounded cases with floating 
circuits inside them, plastic cases with 'double insulated' floating supplies 
- and houses which have an earth line which is not connected to anything. You 
do need to check that the new computer is properly grounded - if necessary 
connect a separate line to ground through the window.

> Nothing was in the sdr.log indicating that the system was trying to lock 
onto WWV.
 
    So presumably it wasn't. Could this be a software problem - such as no 
IRQ allocated? Check in Settings > Control Panel > System > Device Manager 
for allocations.

    Move the radio as far away as possible from the computer and check it's 
aerial and ground connections. Wrap the audio lead 10+ times through a large 
ferrite ring close to the computer, to prevent RFI getting back to the radio. 
Does unplugging the audio lead make any difference to the RFI on the audio 
signal? The ultimate anti interference connection is a fibre optic lead....  
You can screen an unscreened computer, but it is a major task. Computers and 
radios need all the help that you can give them if they are to be used at the 
same time!
    
    Regards, Chris Chapman M1ECJ.

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