I bought [a GPS Disciplined Oscillator (GPSDO)][gpsdo], because I thought it'd be fun for various projects. Specifically I bought [this one][gpsdohw]. I started by calibrating my [ICOM IC-9700][ic9700]. I made sure it got a GPS lock, and connected it to the 9700 10MHz reference port, with a 20dB attenuator inline, just in case. Ok, the receive frequency moved a bit, but how do I know it was improved? My [D75][d75] was still about 200Hz off frequency. [![IC9700 screenshot showing D75][img-d75]...
