Products > Test Equipment
Unknown GPSDO but BG7TBL logo on the circuit board and OCXO !
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hector.pascal:
Hi,
It seems to be a very good general purpose, reasonably quick locking in my location, value for money reference.  The only con is no documentation :(
E.g,  is the TXD NMEA output connector a mono or stereo jack?  The little picture on the back panel could be read either way.
And is that TXD output a genuine +/- RS232  (whether +12/-12V or +5/-5V), or is it the "TTL" version (~0/+5V)?
Also does anyone know if the version with green end panels is significantly different from the latest one (marked 2017/12/05) with the black ends?   Regards H.
charly724:
Hi,
attached is the measurement of the serial output without load, it's 5 V.
I could not find a different between green and black panel version...
Regards Charly
hector.pascal:
My September? 2017 "green" version has a 5V OCXO and 0-5V data (see attachments).  The 10 MHz w/f is 1.84Vptp into hi Z. The data connector is the tip of a 3.5mm stereo plug.  It locks in less than 4 minutes with the antenna sitting downstairs close to the unit. Sadly I have no equipment to verify its accuracy!
hector.pascal:
Hi,
The NMEA "RS232" 0/5V data from my unit was inverted, presumably due to Q1, R7, R8. To get valid data, I inserted a simple outboard transistor inverter at the "RS232" output.
(2N3904, input from the tip of the stereo jack plug via 10k resistor to base, and 1k collector resistor from 5V. The inverted output is then available from the collector.   But note that 0/3.3V data would need collector connected via 1k to 3.3V, instead of 5V.)
Worked fine after that!  Presumably the valid data could be also tapped directly from the GPS module at R8, but I preferred a bit of buffering to allow for any "accidents"!
H-P
Diabolo:
Hello,


Could you post a full photo of the component side?
Next to the Oxco CTS 970-2178-46 there should be a li-ion battery (BT1, 3-volt LIR MS621FE-FL11E), it is absent on your model.

The GPS module is a model VK1612U7M3L :
- http://www.worlduc.com/FileSystem/18/5370/178261/dfa73b3b55474546895252a20d2c6f61.pdf

Ocxo CTS-970-2178-46-10MHZ-5V is used in post # 386:
https://www.eevblog.com/forum/testgear/bg7tbl-gpsdo-master-reference/375/

Regards,
Diabolo
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