Model 206-A Crystal Calibrator
Here is the manual for the 206A. It's just the specs, a short circuit decription, and the schematic.
MODEL 206-A CRYSTAL CALIBRATOR.pdf
PDF-Dokument [345.4 KB]
Model 276 Crystal Calibrator
Here is the manual for the 207 Crystal Calibrator.
Everything is readable including the schematic, but the picture showing board layout is not very good. You can unzip the PDF with Winrar or Winzip.