Dave upgrades his HP/Agilent 53131A frequency counter with an ovenised oscillator module from ebay.
http://www.ebay.com.au/itm/121330209846
http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf
http://www.2917.com/EBAY-images/NOX012166/STP2145A.pdf
http://cp.literature.agilent.com/litweb/pdf/5967-6039EN.pdf
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