[time-nuts] Looking for Motorola VP Oncore for HP 58503a

[Matthew D'Asaro]

Hi,
     I just subscribed to this list but I have been interested in time 
standards for some years and have been reading the archives. My specific 
interest is in an accurate frequency standard for my home lab so that I 
can do my own "calibrations" of the ovenized timebases used in 
oscilloscopes, counters, synthesized generators and the like. I had 
originally thought it would be really cool to own my own primary 
standard and have been trolling eBay for some time looking for an HP 
5061A, but I never really wanted to spend the big $$$$ or gamble on a 
unit in unknown condition having a good tube so I sat on the idea for a 
number of years. However, I have recently started working on a project 
where I really need an accurate frequency reference and after 
researching GPSDOs I decided that is the way I would go.

Last month I bought on eBay a used HP 58503a and matching antenna. 
Unfortunatly, the system would not work (the HP wouldn't even finish 
booting) and when I opened it up I found that the GPS board is 
completely missing. After reading a bunch of back posts from this group, 
it appears that what I need is a Motorola VP Oncore board and that other 
versions (such as the UT+) will NOT work. Unfortunatly, I don't see any 
VP Oncore boards for sale on eBay or elsewhere. This leads me to my 
questions. First, am I correct that I can't use any Oncore version 
except the VP in my 58503a and second, does anyone know of a source for 
an Oncore VP?

Thanks in advance,
Matthew D'Asaro