Hi One use for zener diodes is as RF noise generators ….. the coil probably was there to quiet things down.
Bob > On Apr 11, 2020, at 4:42 PM, ed breya <[email protected]> wrote: > > Rick said: > "In the case of the 10811, I have already posted about the reference diode of > special characteristics. I don't remember all the exact details of how it was > chosen, but it was based on proprietary knowledge." > > This reminds me of something unusual I found in a Vectron 10 MHz OCXO many > years ago. It was busted, and it was a soldered-shut type. I had nothing to > lose in taking it apart, hoping to find the problem and restore it if > possible. It came apart OK, and I found in the densely packed circuitry, a > small RF choke that was burned up. I traced the circuitry enough to figure > out that it was in series with the internal reference regulator diode - a > 1N82X 6.2V TC type. This added some small DC voltage drop to the Zener > voltage, and that's what went to the internal circuitry, and also out to an > external pin. This pin was intended to supply an external pot for tweaking > the EFC line in stand-alone applications, and apparently sometime in its > past, it had been faulted to an excessive voltage, causing the choke to burn > out, and maybe damage to other parts. > > The only things I could figure were that the choke maybe served as a small > copper resistance (+3000 ppm/K or so) to provide some extra degree of > temperature compensation for some reason, or that it was to suppress possible > oscillations from the Zener's negative R in avalanche. > > The choke was one of those little molded types, about the size of a 1/4 W > resistor, and unfortunately burned up and apart too much to read any color > bands. I guessed it to be around maybe up to a few uH, and a few ohms, but > that's as far as I got. I set it aside, thinking someday I'll dig into it > some more, but it still sits in pieces in a box somewhere, remaining a > mystery to me. All I know is, there must have been a reason for it. > > Ed > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
