Well I thought that would get your attention! It's not quite as simple as that, however it CAN be done. First you need a good "mini" tube scavenged out of a 5061A/B. These smaller diameter tubes HP made for 5061A/B replacements are essentially a 5071A tube with different connectors. Then you need an EEPROM removed from a dead 5071A tube that has a thermistor value close to the "mini" tube. Tom Van Baak has the paper on his site, you can read about the results.\ I got installing "mini" tubes into several 5071A units. http://leapsecond.com/corby/HP-5071A-with-5061A-4.docx Also included are the results of using a standard tubes EEPROM on a high performance tube and visa versa to extend the tubes life! Now that I'm done with the experimenting I have two 5071A with good "mini" tubes installed and several good "mini" tubes for sale. Buyers of the 5071A can buy a "spare" tube at a discount. Both 5071A are missing the front door cover and the two perforated side panels. Please contact me off list for details, pictures and plots. Cheers, Corby Dawson