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HP8703D with Phase Lock Cal Fail

Question asked by victot5 on May 21, 2012
Latest reply on Jul 19, 2012 by victot5
Hello, after some weeks of inactivity our HP8703B network analyser got a serious failure.
It shows a warning like:  Phase lock cal failed.
As the equipment has get obsolete it seems impossible to repair it, so i will try that here at our university department.
I measured  the output in CW with an oscilloscope and 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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