John, The only two parameters that must be close are the mass spectrometer, ionizer voltage, and the thermistor value. The starting EM voltage does not matter as the mainframe adjusts it to reach 100na automatically. The 5071A tubes are not labeled with the parameters but you can wait until the original dead tube has warmed up and them quickly remove the connector and measure the original thermistor value. You can also measure the original mass spectrometer voltage with a voltmeter. By the way, when reading out the EEPROMs of the dead tubes I have, the poem is indeed there! I have not been able to find the tube parameters in the EEPROMS. If you used the original EEPROM and just modified the thermistor, mass spec., and ionizer values I think the copyright issue would still not apply! Corby Dawson ____________________________________________________________ Best Weight Loss Program - Click Here! http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTFoYbLvJqCJlw5xJXefJvhmfEEp0Sqnuvf4rj69HLbdfT57aNVpmA/