I don't recall seeing this mentioned here before but if it has been, or if it's just something everyone else has always taken for granted, then apologies in advance from a comatose brain cell for the wasted bandwidth. Until today I'd not previously seen either an NTGS50AA or an NTBW50AA where the unconditioned oscillator frequency was above 10MHz, this from a vast sampling of three of one and two of the other, so perhaps not quite the stuff of certainty:-), and because I'd only ever seen the EFC voltage ramping upwards from it's starting point of 3 Volts had just assumed that the fitted oscillators had been specified or selected such that a 10MHz output was always achieved with an EFC voltage somewhere between 3 and 6 Volts. I have wondered at times why just this limited range was used but hadn't actually paused to consider whether or not I might be seeing less than the full picture. Testing an NTGS50AA today with an oscillator that started, after initial warm up, at a frequency of 10.000 000 4xx MHz, I was thus fully expecting the EFC voltage to ramp upwards as "usual", and that the unit would eventually report a bad oscillator after the EFC had reached 6 Volts without the oscillator frequency crossing 10 MHz, so was quite intrigued when the EFC took the more logical step of ramping downwards instead. So much for jumping to conclusions:-) At this stage I still wasn't sure whether or not this was a fully automated process or the result of some form of "select on test" procedure, but subsequent tests feeding a variable 10MHz signal from an HP3336 generator into another NTGS50AA modified to use off board oscillators have shown that the NTGS50AA, so presumably also the NTBW50AA, will adapt on the fly to accomodate an EFC range of 0 to 6 Volts from the "rest" position of a nominal 3 Volts. It is a bit sad watching the poor thing chasing its tail when the frequency it's seeing isn't actually under its control after all, but overall a much more satisfactory outcome than my original misguided assumptions:-) Regards Nigel GM8PZR _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
