[time-nuts] Making a HP 10811 better

WarrenS warrensjmail-one at yahoo.com
Sun Mar 28 19:02:52 UTC 2010


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.
>>>
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>>
>>
>>
>>
>>
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