kb...@n1k.org said:
> The crystal enclosure may (or may not ⦠who knows ..) be back filled with a
> low level of helium. It does not take much of a backfill for conduction
> inside the crystal holder to dominate the heat transfer vs radiation
> transfer.
How does that compare with conduction t
Hi Folks,
This discussion of temperature measurement with ADCs has crossed into my
professional life and without being too much of a commercial plug just
wanted to mention that I support Linear Technology's temp-to-bits family of
ICs: LTC2983, LTC2984, LTC2986.
Overview: each part has 3 24-
On 6/7/17 7:35 PM, Bob kb8tq wrote:
Hi
Metal actually makes things a bit worse since it has a lower thermal resistance
than glass.
This is also why a high performance dewar is made from glass rather than metal.
Yes, you
can go to weird stuff like titanium (it has been done). You can’t afford
Hi
Metal actually makes things a bit worse since it has a lower thermal resistance
than glass.
This is also why a high performance dewar is made from glass rather than metal.
Yes, you
can go to weird stuff like titanium (it has been done). You can’t afford that ….
If you fill the entire dewar
On Wed, Jun 7, 2017 at 3:18 PM, Bob kb8tq wrote:
> Hi
>
> Consider that a lot of the heat flow is through the glass wall of the
> vacuum gizmo. You want to tie your heater(s) to it in order to create
> an iso-thermal “wall”. Often this is done by gluing the whole assembly
> together.
>
Not glass
For under $20 you can get a OCXO with Si5351A multi output oscillator
chip from QRP-Labs.
http://www.qrp-labs.com/ocxokit.html
No idea just how good it is but this link gives insight into how it was
developed. Designed for WSPR radio transmissions. GPS discipline can
be added.
http://www.ha
Hi
Consider that a lot of the heat flow is through the glass wall of the
vacuum gizmo. You want to tie your heater(s) to it in order to create
an iso-thermal “wall”. Often this is done by gluing the whole assembly
together.
In addition, you probably also want a foam plug in the end
of the beast
On Wed, 7 Jun 2017 22:20:50 +0100
Peter Vince wrote:
> > Additionally: if I would set out to build my own OCXO today, I would
> > go and buy one of those lunch thermos flasks to house everything. Their
> > isolation is higher than anything you can easily build yourself,
> > especially at that siz
Hi
Keep in mind that on a per cubic inch basis, copper is right up there
for creating a thermal mass ….
Bob
> On Jun 7, 2017, at 5:51 PM, Attila Kinali wrote:
>
> Hoi Rick,
>
> On Wed, 7 Jun 2017 14:21:52 -0700
> "Richard (Rick) Karlquist" wrote:
>
>
>> Actually, the oven mass of the E1938A
Hoi Rick,
On Wed, 7 Jun 2017 14:21:52 -0700
"Richard (Rick) Karlquist" wrote:
> Actually, the oven mass of the E1938A is much heavier than the
> 10811 and is made of copper to boot.
[...]
> The crystal case is well connected to the oven mass and gets
> heated by conduction. I don't think radia
Chris wrote:
Assume me goal is to regulate temperer of an aluminum block to within
0.1C, how good must my ADC be? Is an effective 6-bits good enough?
* * *If I scale the input to the ADC such that it os 1.0C from 0 to 63
counts then each cunt is 1/64 C which is about 6 times better t
Hi
The crystal enclosure may (or may not … who knows ..) be back filled with a low
level
of helium. It does not take much of a backfill for conduction inside the
crystal holder to
dominate the heat transfer vs radiation transfer.
Bob
> On Jun 7, 2017, at 5:21 PM, Richard (Rick) Karlquist
> w
Hi
> On Jun 7, 2017, at 4:40 PM, Attila Kinali wrote:
>
> On Wed, 7 Jun 2017 15:25:38 -0400
> Charles Steinmetz wrote:
>
>> Chris wrote:
>>
>>> Assume me goal is to regulate temperer of an aluminum block to within
>>> 0.1C, how good must my ADC be? Is an effective 6-bits good enough?
>>>
On 6/7/2017 1:09 PM, Attila Kinali wrote:
makes the PI loop better behaved. Also the thermal mass of the
crystal holder is quite small. Especially compared ot the 10811.
Actually, the oven mass of the E1938A is much heavier than the
10811 and is made of copper to boot.
Due to the flat puck
On 7 June 2017 at 21:40, Attila Kinali wrote:
>
> Additionally: if I would set out to build my own OCXO today, I would
> go and buy one of those lunch thermos flasks to house everything. Their
> isolation is higher than anything you can easily build yourself,
> especially at that size. I would pla
On Wed, 7 Jun 2017 15:25:38 -0400
Charles Steinmetz wrote:
> Chris wrote:
>
> > Assume me goal is to regulate temperer of an aluminum block to within
> > 0.1C, how good must my ADC be? Is an effective 6-bits good enough?
> >
> > * * *If I scale the input to the ADC such that it os 1.0
On Tue, 6 Jun 2017 19:07:29 -0700
"Richard (Rick) Karlquist" wrote:
> In the E1938A oscillator, we used a PIDI^2 loop. IOW, a PID
> plus a double integrator. This was Len Cutler's idea.
> Once the constants were dialed in, this worked phenomenally
> well in terms of transient response. Even du
On Tue, 6 Jun 2017 16:43:30 -0700
Chris Albertson wrote:
> > . Heck, the STM32F4xx have so much internal noise that the ENOB
> > of their ADC is below 6bit... so low that they even had to write an
> > appnote on how to do averaging to get back to the 12 bits the ADC is
> > spec'ed for. (but don't
I can provide brass gears for your HP 8640 Signal generator.
If any members of the list are interested, please contact me off list.
wa0...@arrl.net
I will be happy to provide the information.
73
Paul K.
WA0BAG
--
Paul K. WA0BAG
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Yes I need one for 1 day, not to keep
In a message dated 6/7/2017 3:19:37 P.M. Eastern Daylight Time,
scmcgr...@gmail.com writes:
Ulrich
I have an operational 8640
Content by Scott
Typos by Siri
> On Jun 7, 2017, at 11:35 AM, Dave Daniel wrote:
>
> There is, or was, a member of the
Ulrich
I have an operational 8640
Content by Scott
Typos by Siri
> On Jun 7, 2017, at 11:35 AM, Dave Daniel wrote:
>
> There is, or was, a member of the Yahoo hp_agilent forum who was making metal
> replacement gears for the HP8640. I believe several members replaced the
> plastic gears wit
albertson.ch...@gmail.com said:
> Assume me goal is to regulate temperer of an aluminum block to within 0.1C,
> how good must my ADC be? Is an effective 6-bits good enough?
I don't think you are asking the right question.
You can build a control loop with a 1 bit ADC. Think of your typical
Hello Ulrich,
I have an 8640 I was going to put up for sale in the next few weeks. It’s in
almost perfect condition. All of the gears are intact with no cracks or
splitting. I think this SG may have been in a lab environment most of it’s
lifetime.
Contact me off list if you are interested.
Da
The good news is that for oven control, you can typically filter the heck
out of the data and the noise may actually help you with dithering if it's
fairly random, so you should be able to get close to the specs. The main
thing you need is stability, linearity should not be a factor. One
limitation
Hi
There is a gotcha with the initial assumption: You want the loop to be
*quiet* at a level well below 0.1C. If it is bouncing around that much,
the second order (rate defendant) tempco of a normal crystal will
become a pretty major issue.
Simple rule of thumb - add at least two bits past whate
One question for the control theory experts.
Assume me goal is to regulate temperer of an aluminum block to within 0.1C,
how good must my ADC be? Is an effective 6-bits good enough?
It seems to me the problem with fewer bits is only quantization noise.
Lets assume 6-bits. This is 1 part in 64.
There is no direct relationship between frequency and stability. For any given
frequency, the stability is determined to a large extent by the technology used
for the oscillator. For instance, at 1 kHz, a quartz crystal is normally more
stable than a tuning fork which is normally better than a L
That makes complete sense, it’s not disciplining anything, just pumping out the
PPS and reporting the variance. I don’t know why I didn’t think of it.
It’s interesting how it jumps around from PPS to PPS.
Thank you,
Jerry
> On Jun 7, 2017, at 2:57 AM, Hal Murray wrote:
>
>
> je...@hanler
There is, or was, a member of the Yahoo hp_agilent forum who was making
metal replacement gears for the HP8640. I believe several members
replaced the plastic gears with the new metal ones and were able to
bring their instruments back to life.
DaveD
On 6/7/2017 8:56 AM, Bert Kehren via time-n
Hi
For something like a crystal oscillator, there is a relation between frequency
and resonator Q. That
gives you a loose correlation between stability and oscillator frequency.
Beyond that, there are
substantial differences between the technologies you are comparing. That is the
main source o
I think it will be difficult to find a well working 8640, plastic gears
will have by now totally disintegrated. What part of it do you need, I may
have something left.
Bert Kehren
In a message dated 6/6/2017 9:06:05 P.M. Eastern Daylight Time,
time-nuts@febo.com writes:
Hi , I am trying
SHORT VERSION: I’ve been trying to figure out what the relationship is between
frequency and stability - if there is one - that is, why oscillators with
higher frequencies tend to be more stable.
LONG VERSION: I got into this by building a home-brew NTP server using a
cesium-disciplined oscill
Hi
Yes, you run both modes at the same time. You wire up two oscillator circuits
to the
same crystal. One runs at the fundamental and the other runs at the third
overtone.
The two have a different temperature coefficient. (yes, that’s a bit weird, but
it is true).
The “offset” between the two
Argh/sorry. I fatfingered something. Wrong list.
--
These are my opinions. I hate spam.
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sobo...@sippysoft.com said:
> SO_BINTIME was ENOTSUPP with IPv6 from the day one.
Thanks. Is that a literal ENOTSUPP? Should I get an error from setsockopt?
Or is that just shorthand for not-implemented?
Do you want a bug report? If nothing else, the man page should be updated.
Just curiou
je...@hanler.com said:
> Chris, I think you are onto something. Running Lady Heather on this unit I
> see a line under âreceiverâ with the term âSawTâ and a parameter of
> 24ns.
> So if we combine this information with what you teach below, itâs starting
> to look like maybe the M12 un
Another thing to watch out for on processor ADCs is their performance near the
supply rails... the AVR ADCs are particularly entertaining below around 300 mV
(with a 5V Vref).
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