Can someone provide a sanity check on my S/N and FOM measurements? I've used the procedure in my manual, but there is one rather vague calculation involving 2.3 e 13 x V403b. I assume this is actually 2.3 e -13 x (noise voltage in mv), because otherwise the other calculations result in absurd values.
I have a high-output tube and got the following measurements: Vpeak -278 mv Vvalley -81 mv Vbase -65 mv which gives a 'flop' of 3.03. Using the more advanced measurements for the high-output tube, I get: Isig 1.97 e -9 Inoise 6.44 e-13 (assuming my comment abut the V403b calculation is correct; I measured a noise voltage of 2.8 mv rms). which gives an S/N ratio of 3059 (!) and a FOM of 7.89. This is all from a 25-year-old CBT, so I'm a bit suspicious. It does lock and stay locked, even in low-flux mode, though. As for the EM voltage, I measured a peak beam current of 3.6 e -9 amps; HP says the acceptable low bound is 8 e -9. This current makes sense, since the tube is so old. So, would it be useful to increase the EM voltage from 1700 (as marked on the CBT and verified) to increase the beam current? I assume doing so would accelerate the deterioration of the EM, though, so maybe I should leave well enough alone. BTW, I had to make up a precision 100 meg probe to do the Vp, Vv, and Vb measurements; my voltmeter has a 1 e 13 ohm input resistance, which makes the technique in the manual useless. (a Solartron 7081 8.5 digit beauty) -- Bill Ezell ---------- They said 'Windows or better' so I used Linux. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.