Bob --

I would lean toward suspecting some RF interference with the new computer.
I have had a lot of problems with this, trying to get WWV or WWVB to come
in strong enough to lock.  I know you said the signal sounds good, but I
think some RFI at the wrong moment could cause SDR not to lock.

Things I would try to reduce RFI:

1.  Isolation plugs (3-prong to 2-prong adaptor) in series with the
computer, the receiver, or both.  

2.  Put a choke in the audio wire from the receiver to the A/D board.  This
fixed the problem for me.  I got a ferrite toriod core from a surplus place
and wrapped the audio cable on it (both high side and low side twisted
together) as many times as I could fit on the core (maybe 50 turns).

3.  Isolate the receiver's output from the computer with an audio coupling
transformer.  I think Radio Shack still sells these.  Connect the computer
and the receiver to good grounds.  See below.

4.  Plug the receiver into a different plug, preferrably fed from a
different circuit breaker.

5.  Ground the computer's chassis to a water pipe with copper strap, not
just a wire as the strap has far less inductance.  Copper strap for this
purpose is available from ham radio stores and marine supply places.  Try
this with the receiver too, or both.

6.  Put a line filter in series with the computer's power cord.  Not the
surge protectors, but a real filter.  These are available from electronic
surplus outlets.  Try this on the reveiver too, or both.

7.  Locate the WWV antenna away from the computer, preferrably by 30 feet
or more.  Use coaxial cable for a feed line to the antenna.

8.  Locate the receiver far from the computer.  Then run just the audio
cable to the computer, and run it through an RF choke as mentioned in #2
above.

If it is some other problem, then I don't know.  I assume the Packard Bell
is a 486 or Pentium, so I would think there isn't a problem with the
interrupt speed.

Let us know what happens.

Karl

_____________________________________________________________________

Public Seismic Network Mailing List (PSN-L)