More twiddling of the OCXOs this afternoon.
- Austron 1250A:Â was tune 375, +3.9e9; now tune 340, +4.5e12
- FTS 1050A: was tune 55000, +2.1e9; now tune 54614, -1.7e12
- Sulzer #1 (2.5 MHz): was tune +0.39, +7.2e9; now tune -0.56 (CCW past zero), -3.2e12
- Sulzer #2 (5 MHz): was tune 9.23, -1.4e9; now tune 9.31, -1.2e11
All these comparisons are against an HP 5061A Cesium standard that tracks GPS at about -2e13.Â The Sulzers have mechanical tuning (flexible shaft to a piston capacitor) and given that they are around 50 years old, setting them is a bit touchy.Â They can take an hour or more to fully settle after adjusting the trimmer.
The goal here isn’t perfection, and getting all these guys to within 1e11 or so is all I need.Â My goal is just to get them close enough to nominal frequency that cycle wrap isn’t likely to occur over long measurement periods.Â I don’t plan to touch any of them again for another year or more.