Help finding documentation for OCXO

[ZBIQ]

Hi!

It is my first topic at EEEVblog. So Hello !

I have recently bought ocxo stable oscillator (for about 9$ - so worth it ). It works fine, but there is no data sheet for this device.
Here is the ocxo photo:
http://img03.allegroimg.pl/photos/oryginal/48/76/94/72/4876947200

The whole pcb is disassembled from GSM transmitter. Marking on it says:
PC9203 V255
RADIOSYSTEM
SWEDEN AB
TVM 351 131 R2
It has FPGA, uC and few memories. There are also connectors: BNC and SMB. So, I think the whole PCB is GPS disciplined oscillator.
I think circuit works (after suppling voltages leds are blinking). But without documentation this board is useless...

Can you help me finding DS for OCXO?
Mateusz 

[fcb]

Vectron maybe able to help.

Else, you can probably reverse engineer the board to work out the connections (which maybe enough for your needs).

[ZBIQ]

Ive done some research on OCXO. I know where goes power supply and where comes out frequency. But there are two more pins. One is connected to DAC (by chip '224 91G722' - opamp??). Another one is unknown (maybe some Vref out?)...
This board has 6 layers (!) - reverse engineering is very hard.

[dannyf]

The dac pin is likely the control / tunning pin: apply a voltage to it to fine-tune the output frequency.

The other is the ground pin, likely.

[TSL]

A better picture of the entire board would help, once we can see the part #'s on all the chips we might get some idea

TT

[babysitter]

Ive done some research on OCXO. I know where goes power supply and where comes out frequency. But there are two more pins. One is connected to DAC (by chip '224 91G722' - opamp??). Another one is unknown (maybe some Vref out?)...
This board has 6 layers (!) - reverse engineering is very hard.

A DAC would only make sense on tuning voltage as dannyf pointed out. If it tunes - just load it with a resistor. Frequency shall jump between loaded and unloaded. The change might be too small to see on a scope, use a frequency counter or listen to it on a shortwave radio, best would be if you would hear a beat note. Tuned to a harmonic the jump would be more distinct.

The additional pin might be reference or for mechanical purposes (stability). If its a reference output you could see if its actually used when you load it with a resistor to ground to reduce it a few mV and check if the DAC output voltage sags accordingly.

[khach]

Piezo 10MHz OCXO and QK Quarzkeramik GmbH 10MHz OCXO from similar board
https://sites.google.com/site/sp7roh/

[ZBIQ]

Thats fantastic ! So, from now I know pinout. Its time to check performance of the OCXO.
Tank you very much !