[R-390] 8640B Contrarian opinion.

[2002tii]

Perry  wrote:

>For a lot less money than a re-furbished and guaranteed 8640 one can 
>buy a HP 8656A/B or HP 8667A series. They are electronically tuned.

The 8656/57 synthesized oscillators don't equal the 8640B where 
close-in spectral purity and low phase noise are concerned.  Note 
that they are not specified for spurious output within 5 kHz of the 
carrier -- and for good reason.  Their output attenuators are prone 
to problems, also, and signal leakage from the enclosure is much 
worse than an 8640B -- enough that it often interferes with 
sensitivity measurements.

There is a reason that re-furbished and guaranteed 8640Bs are so 
pricey -- they still outperform almost everything else in several key 
areas.  But most of us don't buy them re-furbished and guaranteed, so 
we don't pay nearly that much for them (I didn't pay $200 for any of mine).

Best regards,

Don