[time-nuts] Making a HP 10811 better

[Ed Palmer]

So the cold ambient temperature was simulating the retuning of the oven 
temperature as described here:  
http://www.realhamradio.com/z3801a-turning-point.htm and the particular 
unit graphed in the article happened to have the oven temperature a bit 
high.  Sounds like a sunny deck and a cooler of ice (plus your beverage 
of choice, of course) would be useful test equipment to check your 10811 
to see if retuning the oven is necessary.

Warren:
On your list of things to do, checking that the crystal inflection point 
matches the oven temperature should probably come before adjusting the 
thermal gain.

Ed

Bob Camp wrote:
> Hi
>
> The "best at tha cold end" was a function of where the oven was relative to the turn temperature of the crystal. There's actually a bit more to it than that, but that's the simple answer. 
>
> Bottom line - the temperature curve of *your* 10811 likely will be a bit different than what they show. 
>
> A cooler, a small bag of ice, a thermometer, and  a sunny deck in the summer will give you a temperature ramp. That and some patience will give you a pretty good idea of what your oscillator actually looks like. Other techniques may also work, most  provide less of an excuse to drink beer during the experiment.....
>
> Bob
>
>
> On Mar 28, 2010, at 4:20 PM, Ed Palmer wrote:
>
>   
>> Have you considered putting the 10811 in a deep freeze? :-)
>>
>> The March 1981 issue of the HP Journal includes an in-depth article on the 10811A/B.  It talks about the heater, thermal gain, optimization, etc.  Figure 5 on page 21 shows a graph of ambient temperature vs. frequency change.  The figure shows that the lowest frequency changes occur around an ambient temperature of -20C!  Maybe instead of an outer oven we need to use a Peltier cooler.
>>
>> http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf
>>
>> Ed
>>
>> WarrenS wrote:
>>     
>>> Richard wrote approx
>>>       
>>>> ... This is how the Thermal gain can be increase to eliminate temperature drift over typical room variations.
>>>>         
>>> Thank You
>>> Great Idea. Wish I would of thought of that. But Yeah almost as good, Now I know it, can take that away.
>>> That is the type of useful and not obvious information that I was hoping for.
>>>
>>> THANKS SO MUCH
>>> That goes to the top of my list to find a procedure to do it.
>>> You are a true Nut hero.
>>>
>>> WS
>>>
>>> ********************
>>>
>>> ----- Original Message ----- From: "Richard H McCorkle" <mccorkle at ptialaska.net>
>>> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
>>> Sent: Sunday, March 28, 2010 11:32 AM
>>> Subject: Re: [time-nuts] Making a HP 10811 better
>>>
>>>
>>>       
>>>> Warren,
>>>> One thing Rick Karlquist pointed out is a higher thermal gain can be
>>>> realized to minimize temperature effects by optimizing the heater
>>>> transistor balance. The 10811A/B Quartz Crystal Oscillator Operating
>>>> & Service Manual describes the balance circuit in section 8-40. The
>>>> two heater transistors are not equally spaced with Q7 being closer
>>>> to the crystal so rather than 50% of the current flowing thru both
>>>> heater transistors the current in Q8 is set slightly higher at 57%
>>>> +/- 2% in a production unit to apply equal heat at the crystal.
>>>> The typical thermal gain on a production unit is on the order of
>>>> 100 without optimization, but gains of 1000 or more are possible if
>>>> the heater transistor balance is optimized. I was fortunate enough
>>>> to obtain a set of single oven 10811-60158 units that had been
>>>> optimized by an HP engineer for different temperature sensitivities
>>>> and tagged as such. The unit optimized for maximum thermal gain is
>>>> virtually immune to typical room temperature variations. A second
>>>> unit optimized for double oven operation has much lower thermal
>>>> gain and makes a great unit for testing software temperature
>>>> compensation routines and outer oven designs.
>>>>
>>>> Richard
>>>>
>>>>         
>>>>> Time to Push the "reset button"
>>>>>
>>>>> I hope we can all agree what one is not going to find an axes that makes the
>>>>> Frequency modulation that is caused by tapping on the Oscillator, or the
>>>>> table or the airplane, or the boat, to go away, for whatever reasons.
>>>>>
>>>>> Sorry, what I've been falsely referring to as the zero-G axes is actually
>>>>> the "Zero Tilt" angle axes.
>>>>> I have not had problems with My G changing short term, (BUT it would be
>>>>> interesting to see if I can detect the moon overhead).
>>>>> What I do have is some problems with the Osc tilt angle changing due to its
>>>>> position changing a little.
>>>>> It is the Zero-tilt angle axes that works over a very small change of a few
>>>>> degrees at most.
>>>>>
>>>>> On the other hand, the Zero tilt axes is in fact the Max G sensitivity axes.
>>>>> If you want the Min G sensitivity axes, so that there is no change when
>>>>> turning the Osc over, That is 90 deg from the zero tilt axes, which is also
>>>>> how you make the Osc into its best Tilt angle meter.
>>>>> What happens at any G value that is between +1 and -1, or is greater than +1
>>>>> or -1,  I have not tested for, so I'm not qualified to speculate.
>>>>> I am only stating that there is an axes where the Oscillator frequency is
>>>>> exactly the same when you turn it exactly over.
>>>>> AND this is NOT the axes you want to have, If it is going to be tilted even
>>>>> a sub sub fraction of a deg.
>>>>>
>>>>> Now can we get back to making the 10811 Osc better?
>>>>>
>>>>> ws
>>>>>
>>>>> **********************
>>>>> *************************
>>>>> From: "Bob Camp" <lists at rtty.us>
>>>>> Hi
>>>>>
>>>>> If your zero g axis only works over a 1/100 G range, you are looking at
>>>>> something other than acceleration. If you have found an axis with a zero, it
>>>>> should be a just as much a null at 1 mG as at 1 G as at 10 G's. It's also
>>>>> possible that your "zero" is actually a minimum below your test resolution
>>>>> and higher G's bring it up to the point you can measure it. There's no
>>>>> guarantee of a zero being there.
>>>>>
>>>>> Hitting the oscillator makes it vibrate in all three axis, that's not going
>>>>> to be suppressed regardless of which way you have it mounted.
>>>>>
>>>>> Bob
>>>>> *********************
>>>>> On Mar 28, 2010, at 12:42 AM, WarrenS wrote:
>>>>>           
>>>>>> Humm,
>>>>>> Have to admit, I did not consider that as a possibility before.
>>>>>> Maybe when I tap on it, its not microphonics after all that cause the freq
>>>>>> to modulate, but the vibration of the inside stuff that is warming it up.
>>>>>> For every action there is a reaction and for every  nut there is a
>>>>>> wing-it-nut.
>>>>>>
>>>>>> ws
>>>>>> *****************
>>>>>> Hi
>>>>>>
>>>>>> If that's the result you are getting, you are measuring something other
>>>>>> than G sensitivity. Temperature effects possibly.
>>>>>>
>>>>>> Bob
>>>>>>
>>>>>> ****************
>>>>>> On Mar 27, 2010, at 11:02 PM, WarrenS wrote:
>>>>>>
>>>>>>             
>>>>>>> Just a friendly comment about the Zero G turn over point and Vibration
>>>>>>>
>>>>>>> Like Zero temp turn over, Special orientation of the OSC ONLY works good
>>>>>>> over a VERY SMALL range, (maybe a 1/100 of G change)
>>>>>>> It would not help vibration and has no effect on microphonics which are
>>>>>>> likely a bigger problem anyway.
>>>>>>> Try taping you Osc, It's freq will go crazy if monitoring it at high
>>>>>>> resolutions and bandwidths
>>>>>>>
>>>>>>> ws
>>>>>>>
>>>>>>> ************************
>>>>>>>
>>>>>>> Hi
>>>>>>>
>>>>>>> The concrete basement floor is your friend.
>>>>>>>
>>>>>>> Stay as far away from the blower on the furnace as you can. If you have a
>>>>>>> drop forge in the basement avoid it as well :)....
>>>>>>>
>>>>>>> You will indeed have a seismograph, but not a very useful one. There's
>>>>>>> not a lot of G's at seismic frequencies unless you live in an active
>>>>>>> earthquake region. The fundamentals of G's and displacement vs frequency
>>>>>>> are in your favor in that respect.
>>>>>>>
>>>>>>> Bob
>>>>>>>
>>>>>>>
>>>>>>> On Mar 27, 2010, at 12:42 PM, Stanley Reynolds wrote:
>>>>>>>
>>>>>>>               
>>>>>>>> Is the source of the vibration important ? I'm thinking that any
>>>>>>>> vibration that is not on the same axis as gravity. Walking across the
>>>>>>>> lab vs a fan that is out of balance close by. Would a suspended mass
>>>>>>>> mounting help with vibration isolation and damping with rubber pads and
>>>>>>>> springs or would that just make a seismograph ?
>>>>>>>>
>>>>>>>> Stanley
>>>>>>>>
>>>>>>>>
>>>>>>>> ----- Original Message ----
>>>>>>>> From: Peter Vince <pvince at theiet.org>
>>>>>>>> To: Discussion of precise time and frequency measurement <time-nuts at
>>>>>>>> febo.com>
>>>>>>>> Sent: Sat, March 27, 2010 10:51:07 AM
>>>>>>>> Subject: Re: [time-nuts] Making a HP 10811 better
>>>>>>>>
>>>>>>>> Warren,
>>>>>>>>
>>>>>>>>  If you turn over an oscillator, is the frequency change
>>>>>>>> completely reversible (to your "under 1e-12 resolution") when it is
>>>>>>>> restored?  Thinking aloud, if an hour-glass is turned over twice, the
>>>>>>>> final level will be the same, but the grains will be mixed.  A quartz
>>>>>>>> crystal, however, is solid, so hopefully nothing actually moves.
>>>>>>>> Presumably the zero-G axis is with the axis of oscillation at 90
>>>>>>>> degrees to gravity?
>>>>>>>>
>>>>>>>>  Peter (the "other" one :-)
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>                 
>>>>>>>>> Another thing I use it for is to test high resolution Freq meters.
>>>>>>>>> Using a calibrated wedge that I can then slide under one edge of the
>>>>>>>>> zero-G
>>>>>>>>> Osc box, I can
>>>>>>>>> make small, variable, repeatable, freq changes of under 1e-12
>>>>>>>>> resolution,
>>>>>>>>> something pretty hard to do otherwise.
>>>>>>>>> If I want to make BIG changes like 1e-10, I can rotate the box on any
>>>>>>>>> of its
>>>>>>>>> sides and still use the wedge,
>>>>>>>>> and for a quick check of new equipment, I just turn the box over which
>>>>>>>>> then
>>>>>>>>> gives a couple of parts in 1e-9 freq change.
>>>>>>>>> It makes a weird but simple and indispensable variable freq source that
>>>>>>>>> is
>>>>>>>>> useful for many things, such as checking the LOOP TC of a TBolt.
>>>>>>>>>