Yet another GPSDO - UK Vintage Radio Repair and Restoration Discussion Forum

Keith956 · 6th Oct 2022, 4:15 pm

Inspired by Mole42UK's excellent work on a GPSDO (https://www.vintage-radio.net/forum/...ighlight=GPSDO) and the work of James Miller G3RUH (http://www.jrmiller.online/projects/ministd/frqstd0.htm), the GPSDO I have been prototyping for a year now has finally moved on from a breadboard to a PCB.

I added/modified a few things :
- a bufffered, switchable output squarewave of 1KHz, 10KHz, 100KHz, 1MHz and 10MHz since all of those were available from the '390 dividers driven by the 10MHz Isotemp OCXO.
- a 10MHz filtered/buffered sinewave output that can drive 50ohms.
- a PIC that displays the time in UTC, the lock status, number of satellites locked on and the switched output frequency.
- RS232 output for debugging the Jupiter output messages (that were decoded by the PIC)
- onboard +12V and +5V power suply using DC-DC converters (linear ones ran too hot with the ~0.75A drawn by the xtal oven when warming up).

Needless to say a few mistakes were made including initially incorrectly wiring the 12V and 5V supplies which resulted in blowing a Jupiter module (fortunately I had a spare). Rev 2 of the PCB still is not perfect, but it works.

6th Oct 2022, 4:15 pm	#1
Keith956 Heptode Join Date: Jun 2019 Location: Oxfordshire Posts: 738	Yet another GPSDO Inspired by Mole42UK's excellent work on a GPSDO (https://www.vintage-radio.net/forum/...ighlight=GPSDO) and the work of James Miller G3RUH (http://www.jrmiller.online/projects/ministd/frqstd0.htm), the GPSDO I have been prototyping for a year now has finally moved on from a breadboard to a PCB. I added/modified a few things : - a bufffered, switchable output squarewave of 1KHz, 10KHz, 100KHz, 1MHz and 10MHz since all of those were available from the '390 dividers driven by the 10MHz Isotemp OCXO. - a 10MHz filtered/buffered sinewave output that can drive 50ohms. - a PIC that displays the time in UTC, the lock status, number of satellites locked on and the switched output frequency. - RS232 output for debugging the Jupiter output messages (that were decoded by the PIC) - onboard +12V and +5V power suply using DC-DC converters (linear ones ran too hot with the ~0.75A drawn by the xtal oven when warming up). Needless to say a few mistakes were made including initially incorrectly wiring the 12V and 5V supplies which resulted in blowing a Jupiter module (fortunately I had a spare). Rev 2 of the PCB still is not perfect, but it works. Attached Thumbnails