Hi I guess my point was more that there is not a VCO / PLL combo in an OCXO.
If dropping the supply gets you on frequency, then you have moved things a lot with that voltage change. 50 PPM is a lot of delta T on any normal OCXO crystal. That strongly suggests there is something wrong in the control circuit. Bob > On Nov 12, 2017, at 2:52 PM, Mark Goldberg <[email protected]> wrote: > > The standard oscillator, 501-14057 ( > www.wenzel.com/wp-content/parts/501-14057.pdf) will lock to an external 10 > MHz reference and this one is marked "80 MHz" and "15V on the label. Maybe > someone swapped the labels. I did try lowering the supply voltage. It got > to 80 MHz at about 11V and still did not lock to the reference. This > oscillator is specified at 1e-6/year aging. That is way less than it is off > now. > > Mark > > On Sun, Nov 12, 2017 at 12:34 PM, Bob Camp <[email protected]> wrote: > >> Hi >> >> It’s pretty certain that there is no PLL inside an 80 MHz low phase noise >> OCXO. >> If it is 4 KHz off frequency at 80 MHz, that gets you into the 50 ppm >> range. Either >> it is running on a really odd crystal spur or it’s not at the right >> temperature. Drifting >> around by 100’s of Hz ( = ppm’s at 80 MHz) is also a good indication that >> the oven >> is not doing it’s job correctly. >> >> If multiple units do the same thing, either they all got busted being >> puled from gear >> (unfortunately that’s common) or you are running it at the wrong supply >> voltage. >> >> Bob >> >> >> >>> On Nov 12, 2017, at 1:19 PM, Mark Goldberg <[email protected]> >> wrote: >>> >>> The seller has replaced it with one that does the exact same thing, which >>> is weird to have two fail in the same way. They are getting hot and the >>> frequency varies with the input voltage, so I tended to guess not the >>> heater as I don't think it could pull that far over temp, and it always >> is >>> high. If it has an unlocked PLL on the output, with no control, would it >> go >>> to the max frequency? Since the seller seems to be reasonable, I was >> trying >>> to figure out best not to waste both of our's time, and me get a good >> unit >>> and them getting a sale. >>> >>> Mark >>> >>> >>> On Sun, Nov 12, 2017 at 9:22 AM, Bob Camp <[email protected]> wrote: >>> >>>> Hi >>>> >>>> As a guess - the oven circuit has stopped working. Next step >>>> would be to tear it open and trace out the schematic. After that >>>> make reasonable guesses for any parts that are poorly labeled. >>>> >>>> Much of what shows up on eBay has been through the ringer in >>>> China. A high percentage the OCXO's I get on eBay show up with >>>> issues as a result. There is no way to be sure this or that part was >>>> ok before it came out of the gear it was in. It’s always a gamble. >>>> >>>> Bob >>>> >>>>> On Nov 12, 2017, at 10:41 AM, Mark Goldberg <[email protected]> >>>> wrote: >>>>> >>>>> I have obtained a couple 80 MHz Wenzel Oscillators P/N 500-16423A. They >>>> are >>>>> proprietary but similar to the VHF PLO and 501-14057 Oscillators. I >> want >>>> to >>>>> use this to replace the internal oscillator in my Perseus SDR, for >> better >>>>> accuracy and maybe better phase noise. Both of these are way off in >>>>> frequency, about 4-5 kHz high from the ideal 80 MHz, and drift around >>>>> hundreds of Hz. I believe they are broken in some way. The PLL lock >>>> signal >>>>> toggles when I put an input into the 10 MHz reference, but the output >>>>> frequency is not affected. >>>>> >>>>> Wenzel has answered some of my questions, but can't get specific as >> these >>>>> are proprietary to a customer. >>>>> >>>>> Any experts on these oscillators out there? >>>>> >>>>> Thanks, >>>>> >>>>> Mark >>>>> _______________________________________________ >>>>> 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. >>>> >>>> _______________________________________________ >>>> 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. >>>> >>> _______________________________________________ >>> 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. >> >> _______________________________________________ >> 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. >> > _______________________________________________ > 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. _______________________________________________ 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.
