Predict  432.0 us/initial 24

                                          TIME     --:--:-- [?] -- ---

                                          GPS 1PPS Invalid: not tracking
                                          ANT DLY  --
                                          Position

                                          MODE     Hold

                                          LAT      --
                                          LON      --

Hello fellow nuts. Long time. This is 14 years in the making as my notes when I put this away are dated 2009, but I finally figured a few things out and got the Z3817A to discipline the E1938: -------------------------------- Receiver Status ------------------------------- SYNCHRONIZATION ............................ [ Outputs Valid/Reduced Accuracy ] SmartClock Mode ___________________________ Reference Outputs _______________ >> Locked to TIMEREF2: stabilizing freq TFOM 3 FFOM 1 Recovery 1PPS TI +0 ps rel to TIMEREF2 Holdover HOLD THR 1.000 us Power-up Holdover Uncertainty ____________ Predict 432.0 us/initial 24 hrs ACQUISITION ........................................... [ TIMEREF2 1PPS Valid ] Tracking: 0 ____ Not Tracking: 0 ________ Time ____________________________ TIME --:--:-- [?] -- --- ---- GPS 1PPS Invalid: not tracking ANT DLY -- Position ________________________ MODE Hold LAT -- LON -- ELEV MASK -- HGT -- HEALTH MONITOR ......................................................... [ OK ] Self Test: OK | Int Pwr: OK Oven Pwr: OK OCXO: OK EFC: OK GPS Rcv: OK I documented my findings here: https://github.com/charlieh0tel/ee_stuff/tree/main/projects/z3817a and here (partial schematic of the power/interface board): https://github.com/charlieh0tel/ee_stuff/tree/main/projects/z3817a Thanks to Peter Grounds for help back in 2009. I suspect it wants Motorola/i.Lotus on the RXD, but I didn't have a chance to try that. NMEA sentences from a Furuno from a 58503A didn't do anything. I still would like to dump the MPU Flash. -ch ES 73 DE AI6KG