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HP8703B with Phase Lock Cal Failed

Question asked by victot5 on May 23, 2012
Hello, after some weeks of inactivity our HP8703B network analyser got a serious failure.
It shows a warning like:  Phase lock cal failed,  while  shows apparently good EE response performance in the 8.5GHz to 12.3GHz range.
As the equipment has got obsolete it seems impossible to repair it, i will try that here at our university department lab. So I measured  the output in CW with an oscilloscope and for CW< 4GHz one dominant frequency around 2GHz appears.

with an spectrum analyser it can be seen the contributions of other several frequencies like about:
CW= 200MHz -->  the output has= 950MHz, 1.46MHz, 1.5MHz, 2.2G, 2.4GHz contribuitions
CW= 1GHz -->  the output = 990MHz, 1.45MHz, 2.4G, 3.8GHz and other small contributions
CW= 2GHz -->  the output = 950MHz, 1.46MHz, 1.5MHz, 2.2G, 2.4G, 4.7GHz,...
CW= 9GHz -->  the output is dominated by a 7.18GHz  component

I have no idea which the problem could be, perhaps the controller ?, the oscillator or the reference parameters? Unfortunatelly I have only the user manual and did not found a service manual for that HP8703B, to check.but  I have seen one post about a similar problem with a HP8753 NA which gives some hope to recover the NA.
I would appreciate very much any recommendation to fix the problem and to find a similar service manual.

Best regards, 
victor5  

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