During the calibration of two EATON 2075B I discovered that two 2075B supposed to be identical had a different YIG oscillator and a different frequency for the second local oscillator. 

The first 2075B has a YIG from Avantek model YO84-1679 with a frequency 2.0 ~ 4.35Ghz and a second LO with a frequency of 2320Mhz, the second 2075B has a different YIG model YO87-4108 with a frequency 2.51 ~ 4.50 Ghz and a second LO with a frequency of 2470Mhz like the MT2075 from Maury Microwave.
(For memory the second LO of the earlier 2075-2A is 2170Mhz). 

As I only had the maintenance manuals for the 2075-2A and the MT2075C it was difficult to speculate how to calibrate these rigs. 

I've been in touch with Maury Microwave who sent me very kindly the key of this enigma with a document issue from their labs and indicating the cal values for the D/A CONVERTER AND YIG DRIVER ADJUSTMENT for the 3 different second LO:

1) LO 2470 Mhz

2) LO 2320 Mhz

3) LO 2170 Mhz


This calibration chart DOC021809.PDF supplied courtesy of Maury Microwave Corporation.  
Note this instrument has been discontinued since 2000 and is no longer supported by Maury


I hope this document will help you if you discover like I did that there are two different hardware for the same 2075B.


If you need some help I'll try to answer your questions about this.


Best 73's

pf, F5BQP