#37 - A look inside of an Agilent E4400B signal generator HD

Another lucky find from eBay. This Agilent E4400B generator has some problem with fractional PLL. It seems to be unstable, so the instrument periodically shows error 508 "Frac-N Loop Unlocked". The synthesizer was inspected, the block diagram was discussed and the blocks were located on the board. Unfortunately, there was no definite solution to the problem due to lack of appropriate equipment at the moment. If there will be any developments, another video might follow. Calibration guide: http://literature.cdn.keysight.com/litweb/pdf/E4400-90325.pdf Document with the block diagram. It is for a different model, which seems to use the same synthesizer: http://cp.literature.agilent.com/litweb/pdf/E4400-90014.pdf Discussion: http://www.eevblog.com/forum/testgear/a-look-inside-of-an-agilent-e4400b-signal-generator/