did you change jumpers SV1 and SV2 (which switch between differential and single-ended clock input for the DDS chip)? I'm not sure what difference that might make; when I did my phase noise tests, the jumpers didn't seem to make much difference.
One other possibility might be a ground loop problem. 73, John ---- Bob Tracy said the following on 12/30/2005 05:42 PM: > 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 > > > > > > _______________________________________________ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > >
