[time-nuts] HP K34-59991A

[Brian Kirby]

I'm not knocking the HP company - they made a lot of great test 
equipment that was very reliable and held its spec's.

The phase comparator shown, is basically an ex-or circuit.  Its been 
around in many forms - I find reference to it in my old Audio Cyclopedia 
- 1959 - in the Ad-Yu Electronics model 406H precision phase meter - 
called a coincident slicer.

I beleive that Lenkurt and Western Electric used the same circuit to 
phase lock their master frequency oscillators in their frequency 
division multiplexers.  That was back in the 1950's !

Rick Karlquist wrote:

>The manager who hired me at HP in 1979, Mike Fischer, invented the
>circuit in that phase comparator.  You can read his patent if
>you are interested in the theory of it.  (No, I don't have the
>patent #).
>
>Rick Karlquist
>
>
>Had said:
>  
>
>>Well I finally managed to track down a copy of the Op/Srv manual for the
>>HP
>>K34-59991A Phase Comparator.
>>
>>You can download the pdf at   www.to-way.com   click the proper button at
>>the bottom of the page. It is a fairly low resolution scan of a photo
>>copied manual but still plenty usable.
>>
>>Had
>>
>>
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