GPS Disciplined Oscillator (GPSDO) review and teardown
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- เผยแพร่เมื่อ 24 ก.ค. 2024
- In this video I'll be taking an in-depth look at a GPSDO that I bought on ebay a while ago. I'll review its performance, take some measurements and then take it apart to see how they built it.
Visit my website at andybrown.me.uk to see a write up and many more hardware projects. - วิทยาศาสตร์และเทคโนโลยี
You have to give them credit for finding that module inside a shipment of e-waste or whatever and turning it back into a product they can sell.
Probably bought a few pallets of them on the surplus market.
For anyone that finds this video first, there's a lot more detailed information about the module in the following two links:
- www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/
- tipok.org.ua/node/53
The unit talks SCPI and can be made to report status, diagnostic information, etc.
A couple of “I think” comments. In my books the date code 1205 more likely is year 2012 and week 5. And the R01 resistor marking is likely to mean 0.01 ohm, i.e. 10 milliohms. Generally the location of the “R” signifies the location of the decimal point.
Very true. 1205 should be 5th week of 2012
Could you connect a LCD screen to the 50 pin connector, you might get more options to alter the ocxo .
The thin, pale-blue wires are wire-wrap wire, very likely old stock and dirt cheap, since only a few elderly hobbyists are still doing wire-wrapping, although it is still used in the electronics industry for rework on PCB's to correct small layout problems or circuit design errors.
This type of wire is still being sold and used a lot. We use this type of wire a lot as "bodge wire" to make modifications on PCBs or to add probing points to a development PCB.
I still remember soldering a sh.tload of wires on a large SMD microcontroller. These thin wires look like tree stumps under a microscope 😵💫
Could you measure the tuning voltage at the OCXO to determine if it is operating at the limit of the tuning range? (end of life)
Or did you conclude from your investigation of the serial port that it is still working ok?
One of the status messages from the serial port was "Good Accuracy & Stable". I took that to mean that it's still working OK. My guess is that these things are installed with a fixed decommissioning date set in the future and they're replaced then regardless of actual condition.
Good to know, thanks.
what command did you issue to get that returned? Any list of commands?
Why did you take the SMA connector off the rear panel when the extruded case just splits top/bottom? Just needed to take the screws out of the front panel!!
Does the ocxo drift in one direction?
You'd have to look for some studies on that I'm afraid. My intuition would be to say that in the short term the error would be random but in the long term it would depend on the direction of the drift in temperature maintained inside the oscillator 'can'.
The 7806 is a 6V linear regulator. the module is probably a switching regulator/linear regulator combo or something like that. Rather than design one they just bought a module with known, extensively tested characteristics.
Enjoyable video, thanks. Might get one of these.
The 7806 in a 3 pin package is a linear regulator. This device is in a Power-SO8 package and so is most likely a MOSFET.
The PTN04050C it is on is a Texas Instruments boost converter module. It is used here to get the 12V needed for the OCXO from the 5V power supply.
Drew Dastardly Maybe this: www.vishay.com/docs/72995/72995.pdf
Nice Video!
just to investigate the rs232 / db9 connector.. You could take Your Oscilloscope, On pin 5 is GND, on pin 2 you should find a pulsed signal, its TxD. on 3 is RxD. maybe, they have changed / reversed pin 2 and 3, but one of these should send the nema protocol data.
vy 73 de DL1LEP
I'm guessing you mean "Temperature Compensated" and not "Temperature Controlled". HUGE difference.