[time-nuts] FE-5680A software calibration units ?

[Nick Sayer]

I’ve designed and built a small power/interface board for my FE-5680A. It takes DC power from a surplus laptop power supply (16-24 VDC) and uses a buck converter to drop that down to 15v and a 5v LDO to supply the 5v pin. It brings the serial and PPS out to a 4 pin SIP header and the 10 MHz to a separate 2 pin SIP. I’m going to rev the design to use a transistor to drive the “ready” LED, but it’s working fine (since I’m not using the PPS output), since I used a higher than normal series resistor for the LED (560 ohms to +5) for the meantime.

I’ve tested it against GPS and as it came, it had about a 0.5 ppm error. I’ve downloaded the VK4XV calibrator and setting the offset to 1000 *appears* to have squared it within my ability to measure. That suggests that the units for the calibrator are 0.5 ppt. Does that resonate (pun intended) with anyone else’s experience?