Hi, Has anyone had any experience using an external clock with the SDR-1000 they would like to share? I built a 10 mHz GPSDO that seems to be working just fine. It puts out a nice 1.7 V P-P sine wave into a 50 ohm load which is within the +4 to +14 dBm range required by the SDR-1000. I installed the FlexRadio External Clock kit which is just a 14 pin header, some coax, a bnc, and a 50 ohm resistor.
When I try to use the external clock, I get really distorted audio coming out of the radio. I have switched back to the internal oscillator a couple of times just to make sure the problem really was in the external circuit. The radio works normally using the internal oscillator. I don't see any garbage on the external oscillator signal using a 100 mHz scope. One other mystery is the amplitude calibration of the SDR-1000 itself. I am calibrated at -73 dBm using an XG-1 calibrator. When I connect the external oscillator to the SDR-1000 antenna input (using the internal clock) I only get a reading of -2.3 dBm. This is with the preamp off. According to my calculations, it should be reading somewhere around +8 dBm. Anyone have any suggestions on the problem? Bob, K5KDN
