[time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

Bob kb8tq kb8tq at n1k.org
Sun Jun 4 00:54:31 UTC 2017


Hi

The objective of the early work with coolers and OCXO’s was DOD sponsored. Low cost was
not the goal :) The idea was that aging might be much better at the lower turn than at the upper turn. Once they
played around a bit they found that activation energy was a real thing in this case. The improvement in aging
did not justify the significant increase in complexity of the design. The idea has popped up about every ten 
years. Each time the conclusion after building a trial unit is pretty much the same. 

Bob

> On Jun 3, 2017, at 8:18 PM, jimlux <jimlux at earthlink.net> wrote:
> 
> On 6/3/17 2:38 PM, Poul-Henning Kamp wrote:
>> --------
>> In message <CABXq0ZCZLhBjpZwt+JTXTgR+xGPraO9x9ewKWXs+JAYe2h87Sw at mail.gmail.com>
>> , "Donald E. Pauly" writes:
>> 
>>> Electronic thermal coolers did not exist then
>> 
>> http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html
> 
> I'm not sure about fancy coolers.. Yeah, people showed that the effect worked, but I think they really didn't come into their own until the modern ones that are omnipresent in 12V powered beer coolers and the like were developed.  That was 70s according to the article.
> Borg Warner (of clutch, brake, and gearbox fame) apparently had one in 1960.
> http://www.thermoelectric.com/2010/archives/library/Ads%20in%20the%2060's.PDF
> 
> So they existed, but were pretty exotic. would a crystal oscillator builder have wanted to fool with one?  Hey, there have been people tinkering with almost everything forever.
> 
> 
>> 
>>> Electronic temperature sensors did not exist either.
>> 
>> https://en.wikipedia.org/wiki/Resistance_thermometer#History
>> 
> 
> Yep... and thermocouples have been used for thermometry for a long time too. Thermistors, for that matter, nonlinear as all get-out, but readily available.
> 
> In the 50s, a *transistor* oscillator would have been pretty unusual. I'm not sure they could work at a high enough frequency.  You'll note that the early "transistor radios" were basically TRF designs for the AM band, and the transistor basically provided audio gain, not RF gain.
> 
> http://www.junkbox.com/electronics/sheets/GE_2N107_Datasheet.jpg
> 
> I guess the regen receiver must have had some gain at 1 MHz. I found an old GE datasheet that gives the ft of 0.6 MHz. (and the hfe wasn't bad, 20, at DC, probably)
> 
> But you sure weren't building a 5MHz or 10 MHz oscillator with a 2N107 or a CK722.  Or the 2N170 NPN, which I am surprised to find you can still buy (and cheaper, in constant dollars, than originally).
> 
> 
> 
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