[time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[Mark Goldberg]

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 <kb8tq at n1k.org> 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 <marklgoldberg at gmail.com>
> 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 <kb8tq at n1k.org> 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 <marklgoldberg at gmail.com>
> >> 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
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