[time-nuts] Sputnik and the HP 523B counter
richard at karlquist.com
Thu Oct 4 14:35:51 EDT 2007
Murray Greenman wrote:
>> L.A. Meacham's patent in 1938 was also the earliest mention I know of
> which include a lamp as a PTC amplitude stabilizer.
> No doubt you've all read Rick's papers about the HP E1938A which uses a
> bridge oscillator. A few more bits in it than Meacham's original, or the
> HP 523B!
> Murray ZL1BPU
The E1938A project started out as a Meacham bridge oscillator
and the number was chosen because it was the date of invention
of that oscillator. Eventually, we realized that design wasn't
going to work for us and we had to invent our our bridge oscillator.
The lamp thing is interesting because there is a lot of HP folklore
that has grown up around the HP garage, the invention of the 200A
oscillator, etc, and it seems that Bill Hewlett has gotten credit
for the lamp stabilization idea. Possibly, he independently invented
it, since he filed 6 months after Meacham did, but long before
the Meacham patent was granted. Hewlett also copied or reinvented
the idea of a bridge oscillator. His real contribution was to harness
Meacham's previous technology to enable him to eliminate the
inductor from the oscillator, which allowed him to raise the
impedance level high enough to allow air variable capacitors to
be used. It was a great design, whoever invented it.
(According to tradition, the model number 200 was used instead
of 100 to give the impression that this wasn't the first HP
The original Hewlett patent is on display at Agilent
headquarters where I work. I was kind of surprised that
HP ("HP Invent") let Agilent have it. I am also pleased
that in the HP Archives museum, on the first shelf, in the
center, is a *working* 5071A. There is also, of course, a
200A oscillator on display.
The above are my own opinions and don't represent Agilent or HP.
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