Drift Testing Revealed a Kit Bug

Looking at my projects page:

http://wb9kzy.com/projects.htm

I found this image of the output of a VFO drift test:

source: http://wb9kzy.com/ssspcba3.gif

The idea was to use a frequency counter with  Morse Code output to measure the drift of a VFO.  A PC "listened" to the Morse Code and kerchunked the results into a file.  That file was then imported into a spreadsheet and plotted.

The interesting part of this test were the spikes.  Looking at the raw data it was easy to see the problem was with the PIC based counter since the spikes were always 256 Hz away from the other spikes.  Using a stable DDS source it was easy to zero in on the frequencies which caused the problem.  This wouldn't normally be noticed by a user but the data and especially the plot made it easy to see.

I mentioned this to the kit designer and he fixed the bug.

Unfortunately PCs don't have parallel printer ports anymore so one of these days I will have to figure out how to use a USB to PIC interface to bring this datalogging counter idea into the 21st century.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm