Hello there,
I'm trying to build a low phase noise signal generator with a Morion MV89 OCXO.
( http://www.morion.com.ru/catalog_pdf/MV89-OCXO.pdf )
The 10 MHz Sine coming from the MV89 shall be converted to a 10 MHz rectangle
with the LTC6957-3 (
It is AC coupled. In fact, many of these units have a bad capacitor and a very
low output. If you get one like that, you will need to open the can and replace
the SMT capacitor.
I believe it is designed to drive a 50 ohm load but I do not know what effect
that will have on the phase noise.
One thing to be aware of on the MV89 is that it is a 5 MHz osc that uses a
freq doubler.
On the ones I've tested, without further filtering, every other cycle's
period is different by ~ 1 ns or so.
For a time nut that likes to see 1ps jitter, it is a whole lot of cycle to
cycle edge jitter
Hi
You would want a 50 ohm load on the output of the OCXO. Based on recent
experience, you may have to buy 10 or more before you find one that is
reasonably close to working correctly. The low output issues are far from the
only problem on these units.
Bob
On Nov 6, 2013, at 9:27 AM,
Ok... maybe i´ll make a not so smart question but... if the MV89 is bad,
what´s the recomended parts from ebay for something like that? (10MHz
OCXO to upgrade some sort of equipment)
(I´m asking because I did almost the same thing than our friend Hagar...
I noticed that the MV89 wasn´t as
Hi
All of the eBay OCXO’s are pulled from scrap gear. If they have been on eBay
for a while, it’s a good bet that the gear has been pretty well picked over.
The only time you can get fairly good parts is when the first hit the market.
Bob
On Nov 6, 2013, at 5:54 PM, Daniel Mendes
I think I may need to change the LPF feeding the EFC in my GPSDO to get rid of
dithering jitter. Is there any point in adding a resistor and cap in the EFC
line, or do I need to go back and change the values in the op-amp circuit
feeding it? Currently an op-amp directly feeds the EFC pin. I
Hello Bob,
If you think you are getting any high frequency into the EFC control - it
may be worth putting a(nother) low-pass filter in there. Are you measuring
noise on that line?
Do you have a snap-shot of a schematic? Or, can you take a picture of that
circuit? I would hazard a guess you
Bob,
Most EFC circuits are relatively high impedance, i.e., around 50K. So,
we are talking micro amps of current flow.
If there is jitter it is most likely somewhere else in the circuitry OR
you are seeing the natural noise in the GPS system.
BillWB6BNQ
Bob Stewart wrote:
I think
Mark,
What type of real-time surveying software are you using? I'm looking for
surveying/plotting software for Linux to keep a close on the timing stability
of my Adafruit.
Bob - AE6RV
From: Mark Sims hol...@hotmail.com
To: time-nuts@febo.com
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