Gerry O’Hara shows you how to install the 500kHz calibrator for an Eddystone 730/4 into an S940 he was working on. The S940 has reasonable scale accuracy, claimed to be 0.5% on all ranges in the specifications – sounds ok, but that’s 150KHz at 30MHz, so it would be useful to have a calibration signal (‘pip’) to inject when needed. 500KHz crystal calibrator in an Eddystone S940