[time-nuts] Wenzel VHF PLO Oscillators Off Frequency
kb8tq at n1k.org
Sun Nov 12 14:34:48 EST 2017
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.
> 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.
> On Sun, Nov 12, 2017 at 9:22 AM, Bob Camp <kb8tq at n1k.org> wrote:
>> 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.
>>> On Nov 12, 2017, at 10:41 AM, Mark Goldberg <marklgoldberg at gmail.com>
>>> I have obtained a couple 80 MHz Wenzel Oscillators P/N 500-16423A. They
>>> proprietary but similar to the VHF PLO and 501-14057 Oscillators. I want
>>> 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
>>> 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?
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