Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Bob Camp]

Hi

There are two things you may be talking about:

1) The pressure springs on things like FT-243 holders, they are generic springs.

2) The connection leads on plated blanks, they are indeed strange *and* 
soldering to the blank is a big problem. 

I’m guessing you are in bucket number 2. 

Bob


> On Jun 4, 2016, at 1:41 PM, Mike Cook  wrote:
> 
> Thanks all for your advice, hints, tips and links. Lots to read , do and some 
> hardware to check.  I don’t have a frequency generator so I’ll have to go 
> another route. 
> 
> Oh. One last Q. Has anyone tried repairing the « spring » wire electric 
> connections on large quartz plates. In one large unit I have they had 
> corroded and dropped the plate, luckily no damage.  I have done one, but I 
> have no Idea what the original wire composition was so have certainly induced 
> some stray capacitance/resistance. It is possible that it was a filter rather 
> than a frequency source as it was not in a vacuum. 
> 
> Have a good one.
> 
>> Le 4 juin 2016 à 18:49, Bernd Neubig  a écrit :
>> 
>> 
>> Tim Shoppa wrote:
>>> The Pierce logic-gate-biased-active oscillator is pretty reliable to start 
>>> and will oscillate somewhere with most crystals from kHz to MHz.
>>> As you found out, it will often come up on one of many overtones.
>>> To reduce chance of coming at an overtone, a series resistor from logic 
>>> gate output to the crystal is often enough. If not, a RC low-pass will cut 
>>> down even further (although of course adding phase shift.)
>> 
>> This is certainly the easiest and fastest way for a go/no-go test and to 
>> find the approximate resonance frequency. 
>> In the attached circuit diagram make CX1 and CX2 about 10 pF and RGK several 
>> MegOhms.
>> The inverter gate should be preferably an unbuffered HCMOS or other fast 
>> inverter.
>> For crystals in the MHz range you can replace RV by a short, for kHz 
>> crystals make it a few kOhms. If testing small watch crystals @ 32768 kHz or 
>> around, RV should be 100 kOhm at least. RV reduces the crystal drive level 
>> (RF current) to an acceptable level to avoid overloading or even damaging of 
>> the crystal. For low frequency crystals the RV-CX2 lowpass also avoids 
>> start-up at the overtone.
>> It is recommended to add a second inverter gate at the output to isolate 
>> your oscilloscope or counter input from the oscillator stage. Add some >330 
>> ohm in series to the output of the 2nd inverter, if you connect a coaxial 
>> cable. Then terminate the coax at the oscilloscope or frequency counter end 
>> with 50 Ohms, so the square wave form will be roughly maintained.
>> 
>> In this circuit the crystal will not operate at its series resonance, but at 
>> a load resonance with load capacitance of something between 8 pF and 10 pF 
>> (depending on the inverter input and output capacitance plus the stray 
>> capacitances of your test fixture).
>> If you want to operate the oscillator at a (low) overtone, such as 3rd (or 
>> maybe 5th), you must add a series combination of 10 nF plus an inductor in 
>> parallel to CX2. The 10 nF is to avoid DC short-circuiting of the output. 
>> The inductor together with CX2 must have a resonance frequency mid between 
>> fundamental mode and 3rd overtone (not at one of them). So the tuned circuit 
>> acts like a capacitor at the 3rd OT and is inductive at fundamental mode 
>> (thus the phase condition for oscillation is not fulfilled at the 
>> fundamental mode)
>> Have fun
>> 
>> Bernd
>> DK1AG 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> "The power of accurate observation is commonly called cynicism by those who 
> have not got it. »
> George Bernard Shaw
> 
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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Brooke Clarke]

Hi George:

A Crystal Activity Meter is the most straight forward way:
http://www.prc68.com/I/Xam.html

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.

 Original Message 

Hi,

I have a number of crystals either in glass, bakelite, ceramic or metal 
housings that I would like to get resonating . They are of three basic types.
  Square, or rectangular flat
  Round flat
  Bar  square section
Sizes range from 2-10cm or more in the longest face.

Some have frequency markings. ranging from IKHz 5MHz.
Others have none.
Some are of  Military origin, probably radios and as they have markings I can 
probably find a schematic from the radios to see how to proceed.  There may be 
dedicated testers still around. I am not so interested in this bunch at the 
moment.
Others have no known origin so I have no idea what oscillator circuits were 
used with them.
In terms of vintage, I would guess pre 1940  to late 50s

I have built a little Pierce circuit an tried a few. Some of the later 1-5MHz 
crystals will oscillate but there are a lot of parasitic signals as well as the 
supposed fundamental. I cannot make any of the low frequency / big crystals to 
react.

So my question:
If you had a crystal with unknown frequency and drive requirements that you 
wanted to investigate. How would you go about it?

If I can get them going I will share the Adevs. I don’t have a spectrum 
analyser so I can’t do phase noise.

Regards

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Charles Steinmetz]

Tim wrote:


The Pierce logic-gate-biased-active oscillator is pretty reliable to start
and will oscillate somewhere with most crystals from kHz to MHz.

As you found out, it will often come up on one of many overtones.

To reduce chance of coming at an overtone, a series resistor from logic
gate output to the crystal is often enough. If not, a RC low-pass will cut
down even further (although of course adding phase shift.)


The general strategy for discouraging overtone operation and other 
unwanted modes at frequencies above the crystal fundamental is to design 
the gain element to have decreasing gain at higher frequencies.  The 
figure attached below (from Hayward's "introduction to RF Design") shows 
one common implementation.


One of Bernd's papers has some helpful information about low-frequency 
crystals and oscillator circuits.  See pp. 1-3 of:




Best regards,

Charles


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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Szeker K.]

Mike,

XTALs does work in air, or better: dry gases (i.e. nitrogen) too, but OK;
quality exemplares are (for better, spurious free, oscillating) in vacuum...

Karl


Virenfrei.
www.avast.com

<#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

2016-06-04 19:41 GMT+02:00 Mike Cook :

> Thanks all for your advice, hints, tips and links. Lots to read , do and
> some hardware to check.  I don’t have a frequency generator so I’ll have to
> go another route.
>
> Oh. One last Q. Has anyone tried repairing the « spring » wire electric
> connections on large quartz plates. In one large unit I have they had
> corroded and dropped the plate, luckily no damage.  I have done one, but I
> have no Idea what the original wire composition was so have certainly
> induced some stray capacitance/resistance. It is possible that it was a
> filter rather than a frequency source as it was not in a vacuum.
>
> Have a good one.
>
> > Le 4 juin 2016 à 18:49, Bernd Neubig  a écrit :
> >
> >
> > Tim Shoppa wrote:
> >> The Pierce logic-gate-biased-active oscillator is pretty reliable to
> start and will oscillate somewhere with most crystals from kHz to MHz.
> >> As you found out, it will often come up on one of many overtones.
> >> To reduce chance of coming at an overtone, a series resistor from logic
> gate output to the crystal is often enough. If not, a RC low-pass will cut
> down even further (although of course adding phase shift.)
> >
> > This is certainly the easiest and fastest way for a go/no-go test and to
> find the approximate resonance frequency.
> > In the attached circuit diagram make CX1 and CX2 about 10 pF and RGK
> several MegOhms.
> > The inverter gate should be preferably an unbuffered HCMOS or other fast
> inverter.
> > For crystals in the MHz range you can replace RV by a short, for kHz
> crystals make it a few kOhms. If testing small watch crystals @ 32768 kHz
> or around, RV should be 100 kOhm at least. RV reduces the crystal drive
> level (RF current) to an acceptable level to avoid overloading or even
> damaging of the crystal. For low frequency crystals the RV-CX2 lowpass also
> avoids start-up at the overtone.
> > It is recommended to add a second inverter gate at the output to isolate
> your oscilloscope or counter input from the oscillator stage. Add some >330
> ohm in series to the output of the 2nd inverter, if you connect a coaxial
> cable. Then terminate the coax at the oscilloscope or frequency counter end
> with 50 Ohms, so the square wave form will be roughly maintained.
> >
> > In this circuit the crystal will not operate at its series resonance,
> but at a load resonance with load capacitance of something between 8 pF and
> 10 pF (depending on the inverter input and output capacitance plus the
> stray capacitances of your test fixture).
> > If you want to operate the oscillator at a (low) overtone, such as 3rd
> (or maybe 5th), you must add a series combination of 10 nF plus an inductor
> in parallel to CX2. The 10 nF is to avoid DC short-circuiting of the
> output. The inductor together with CX2 must have a resonance frequency mid
> between fundamental mode and 3rd overtone (not at one of them). So the
> tuned circuit acts like a capacitor at the 3rd OT and is inductive at
> fundamental mode (thus the phase condition for oscillation is not fulfilled
> at the fundamental mode)
> > Have fun
> >
> > Bernd
> > DK1AG
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> "The power of accurate observation is commonly called cynicism by those
> who have not got it. »
> George Bernard Shaw
>
> ___
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> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
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Re: [time-nuts] HP 106a oscillator connectors question

[Oz-in-DFW]

Several have suggested that these are 10-32 connectors.  If this is
true, a 10-32 nut will thread on them with no trouble.  I believe these
**may** be the 1/4" diameter variant that was 93 ohm characteristic
impedance.  I **think* they are called an S-93.  Still 32 tpi, but 1/4"
in diameter. You can test the thread pitch with a 6,8, or 10-32 bolt.
There was another even more obscure connector that used a coarser pitch. 

And before the 'not 50 ohm' firestorm starts - it doesn't matter.  This
is only 6" or so of cable, the mismatch impact is miniscule at this
frequency.  They were far more concerned with mechanical ruggedness.

On 6/3/2016 4:04 PM, cdel...@juno.com wrote:.



> Need help identifying the RF connectors on the unit.
>
> They are not SMA but look to be the same diameter. would need two
> adaptors or a couple old cables with the matching connector I could
> splice into. I had to poke in a wire and use clip leads!
>
> Cheers,
>
> Corby
>


-- 
mailto:o...@ozindfw.net
Oz
POB 93167 
Southlake, TX 76092 (Near DFW Airport) 



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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Mike Cook]

Thanks all for your advice, hints, tips and links. Lots to read , do and some 
hardware to check.  I don’t have a frequency generator so I’ll have to go 
another route. 

Oh. One last Q. Has anyone tried repairing the « spring » wire electric 
connections on large quartz plates. In one large unit I have they had corroded 
and dropped the plate, luckily no damage.  I have done one, but I have no Idea 
what the original wire composition was so have certainly induced some stray 
capacitance/resistance. It is possible that it was a filter rather than a 
frequency source as it was not in a vacuum. 

Have a good one.

> Le 4 juin 2016 à 18:49, Bernd Neubig  a écrit :
> 
> 
> Tim Shoppa wrote:
>> The Pierce logic-gate-biased-active oscillator is pretty reliable to start 
>> and will oscillate somewhere with most crystals from kHz to MHz.
>> As you found out, it will often come up on one of many overtones.
>> To reduce chance of coming at an overtone, a series resistor from logic gate 
>> output to the crystal is often enough. If not, a RC low-pass will cut down 
>> even further (although of course adding phase shift.)
> 
> This is certainly the easiest and fastest way for a go/no-go test and to find 
> the approximate resonance frequency. 
> In the attached circuit diagram make CX1 and CX2 about 10 pF and RGK several 
> MegOhms.
> The inverter gate should be preferably an unbuffered HCMOS or other fast 
> inverter.
> For crystals in the MHz range you can replace RV by a short, for kHz crystals 
> make it a few kOhms. If testing small watch crystals @ 32768 kHz or around, 
> RV should be 100 kOhm at least. RV reduces the crystal drive level (RF 
> current) to an acceptable level to avoid overloading or even damaging of the 
> crystal. For low frequency crystals the RV-CX2 lowpass also avoids start-up 
> at the overtone.
> It is recommended to add a second inverter gate at the output to isolate your 
> oscilloscope or counter input from the oscillator stage. Add some >330 ohm in 
> series to the output of the 2nd inverter, if you connect a coaxial cable. 
> Then terminate the coax at the oscilloscope or frequency counter end with 50 
> Ohms, so the square wave form will be roughly maintained.
> 
> In this circuit the crystal will not operate at its series resonance, but at 
> a load resonance with load capacitance of something between 8 pF and 10 pF 
> (depending on the inverter input and output capacitance plus the stray 
> capacitances of your test fixture).
> If you want to operate the oscillator at a (low) overtone, such as 3rd (or 
> maybe 5th), you must add a series combination of 10 nF plus an inductor in 
> parallel to CX2. The 10 nF is to avoid DC short-circuiting of the output. The 
> inductor together with CX2 must have a resonance frequency mid between 
> fundamental mode and 3rd overtone (not at one of them). So the tuned circuit 
> acts like a capacitor at the 3rd OT and is inductive at fundamental mode 
> (thus the phase condition for oscillation is not fulfilled at the fundamental 
> mode)
> Have fun
> 
> Bernd
> DK1AG 
> ___
> time-nuts mailing list -- time-nuts@febo.com
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> and follow the instructions there.

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] Mystery hp Ovens For Sale

[Ian Stirling]

On 06/04/2016 08:24 AM, Bob Camp wrote:


Not accurate, but at least a hand waving sort of number:


Bob,

 It serves a crystal calibrator marker on each 100 kHz of a
ten inch dial 600 kHz wide. It is good enough for the job,
but not really in the time-nuts realm, except for the accuracy
required.

Ian, G4ICV, AB2GR
--

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[time-nuts] HP 106a oscillator connectors question

[cdelect]

Thanks for all the info.

They are the 1/4-32 (S-93 compatible) Microdot !!!

I ordered a double ended cable and will cut it in half to give me the two
connections I need (5Mhz out and EFC in).

Cheers,


Corby

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[time-nuts] A Symmtricom GPSDO Board

[Hui Zhang]

Dear group:
Does anyone familiar with this Symmtricom GPSDO board? I have searched on 
internet but I have not found any manual or technical infomation about it. It 
seems can use a RS-232 cable and simple SCPI or serial command to control it, 
just like HP 58540 or other GPSDO  board that I had, and there is a blank place 
on PCB that seems can install a big OCXO or SUB-Board? I don't sure, so I would 
like to find more detail of this board, it has a reasonable price so I can get 
one. Any information will be appreciated.


Here is the some pictures.
http://www.dz98.com/tp/an78-3.jpg
http://www.dz98.com/tp/an78-1.jpg




Regards.


Hui Zhang /BA6IT 
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Re: [time-nuts] A Symmtricom GPSDO Board

[Bruce Griffiths]

More likely the missing GPS receiver board is installed over the ground plane.
Bruce
 

On Sunday, 5 June 2016 4:11 PM, Hui Zhang  wrote:
 

 Dear group:
    Does anyone familiar with this Symmtricom GPSDO board? I have searched on 
internet but I have not found any manual or technical infomation about it. It 
seems can use a RS-232 cable and simple SCPI or serial command to control it, 
just like HP 58540 or other GPSDO  board that I had, and there is a blank place 
on PCB that seems can install a big OCXO or SUB-Board? I don't sure, so I would 
like to find more detail of this board, it has a reasonable price so I can get 
one. Any information will be appreciated.


Here is the some pictures.
http://www.dz98.com/tp/an78-3.jpg
http://www.dz98.com/tp/an78-1.jpg




Regards.


Hui Zhang /BA6IT 
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[time-nuts] How to get unknown frequency quartz crystals oscillating

[Mike Cook]

Hi,

I have a number of crystals either in glass, bakelite, ceramic or metal 
housings that I would like to get resonating . They are of three basic types.
 Square, or rectangular flat   
 Round flat 
 Bar  square section
Sizes range from 2-10cm or more in the longest face.

Some have frequency markings. ranging from IKHz 5MHz. 
Others have none.
Some are of  Military origin, probably radios and as they have markings I can 
probably find a schematic from the radios to see how to proceed.  There may be 
dedicated testers still around. I am not so interested in this bunch at the 
moment. 
Others have no known origin so I have no idea what oscillator circuits were 
used with them. 
In terms of vintage, I would guess pre 1940  to late 50s 

I have built a little Pierce circuit an tried a few. Some of the later 1-5MHz 
crystals will oscillate but there are a lot of parasitic signals as well as the 
supposed fundamental. I cannot make any of the low frequency / big crystals to 
react.

So my question:
If you had a crystal with unknown frequency and drive requirements that you 
wanted to investigate. How would you go about it?

If I can get them going I will share the Adevs. I don’t have a spectrum 
analyser so I can’t do phase noise.

Regards

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] Mystery hp Ovens For Sale

[Mike Cook]

> Le 4 juin 2016 à 06:59, Ian Stirling  a écrit :
> 
>  It looks like the quartz is in the sealed glass "valve", or "tube".
> 
>  I have removed a similar glass vacuum enclosed 100 kHz frequency
> marker generator from my Eddystone EA12 receiver that I bought from
> Tom Roberts, G3YTO (SK 1985), in September 1978. I don't use the EA12
> any more and I wonder what kind of timing device I can make from this
> beautiful slab of quartz, approximately 28 x 5 x 2 mm. I don't have a
> data sheet for it, but I can see which pins are connected to the quartz.
> In the receiver, it has a spring stabilized black metal cover that mates
> to the socket. I suspect that is so that the thirteen valves and their
> heaters create a thermal equilibrium and the black shroud lets the
> crystal bathe in it. I ran the EA12 24/7 from then until I bought and
> used an IC-735 in January 1987.

If you haven’t yet thrown out the EA12 you could try to trace the oscillator 
circuit into which it was plugged, recover the socket and duplicate the circuit 
with modern components. Once working you could add a divider circuit and 
include it in a led clock.  

I have been trying to get some old crystals  singing again using a Pierce 
circuit. Results are not brilliant. 
I could start some of the later 1-5MHz range , but had no luck with low 
frequency. I cannot get really clean output from even those that start so I am 
missing something. Some of the slabs are giants ( one marked 1292Hz +/- 10^-5) 
and I would love to get them started. Some of them are real works of art as 
well. 

I’ll post to a new thread with a req. for ideas.

> 
> It is a GEC Crystal Unit, 100 kHz, serial number 82690 and type JCF/193,
> "Made in England", and it looks like it means business.
> 
> Ian, G4ICV, AB2GR
> --
> 
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"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] Transformer inrush current and transformer simulation

[Chris Albertson]

Don't let the start of the simulation be the power on time.  Best to
set up the AC mains volts at zero volts for a half second then go up
to 120 VAC.  So you actually simulate the power switch.  The time
before the start of the run is not defined

Also you should Google "spice transformer model" and see how others
have done it.  You will need to add some extra inductors and series
resistance.  As you found the Spice model does not have magnetics in
it.  It is simply a pair of coupled inductors.

On Fri, Jun 3, 2016 at 10:40 AM, Attila Kinali  wrote:
> On Fri, 03 Jun 2016 12:37:26 -0400
> "Mike Monett"  wrote:
>
>> I found a significant error in the LTspice analysis. I was wondering how
>> the current could jump instantaneously at zero when the voltage is applied
>> at the peak. That violates magnetism.
>>
>> It turns out it doesn't. When LTspice starts an analysis, it first
>> calculates the operating point. For the Sine voltage source at 90
>> degrees, it applies the full voltage across the load. In this case,
>> it was 169.7V across 1 ohm, resulting in 169.7 Amps. That is what
>> was plotted, and is a significant error.
>
> Actually, spice (the engine behind LTspice) does a DC analysis before
> almost all modes of operation. This DC analysis has the intention to
> start the circuit from a steady-state point and thus to reduce simulation
> time. In order for this to work properly, you have to specify the DC voltage
> and currents for all sources correctly. Spice messes this up at times
> making the first part of a transient simulation worthless (it has even
> worse problems when you do an AC analysis). Additionally LTspice hides
> too much of these small complications for the problems to be visible to
> the untrained eye and also at times makes it harder to provide the correct
> values. Thus, caution is advised.
>
> The general rule of "Never trust a simulation you haven't
> forged yourself" applies.
>
>
>> Out of 13 examples I analyzed, I found only one that involves unloaded
>> transformers.
>>
>> I found many references that discuss transformer inrush current caused by
>> core saturation. This is a serious problem as it puts stress on the
>> components and reduces operating life.
>
> I only had a quick glance at your webpage, but it seems that you used
> the standard LTspice transformer model. Unfortunately, this is not a
> good model to study this kind of behaviour. For one, the only loss considered
> in the model is the winding coupling, it doesn't even directly consider
> resistive losses in the windings. In this case, the two most important effects
> that you need to include are saturation and core losses, which are both
> frequency dependent. The cores of electric machine transformers are very
> poor when it comes to their "high" frequency behaviour. Where high frequency
> starts somewhere closely above mains frequency. Ie 1kHz is already so far off
> that somewhere around 90% of the energy would be dissipated in the core.
> The sharp rise in voltage and the leading inrush current have frequency
> components that are way higher than mains frequency. Hence the linear model
> you used will give inaccurate results, to put it mildly.
>
>
> Unfortunately, building an accurate transformer model in spice is not
> easy and depends on higher order functions that might or might not be
> available in the flavour you use. Not to mention that you will need
> to have good (measured) numbers on the non-ideal behaviour of a transformer,
> which are also not easy to get by.
>
>
> Attila Kinali
>
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] HP 106a oscillator connectors question

[Charles Steinmetz]

Corby wrote:


Need help identifying the RF connectors on the unit.


Original MALCO connectors:

   

   

Instruction sheet (note that these connectors require an installation tool):



Pasternack makes an adapter to BNC-F (at $56 each):



Fairview also has BNC adapters:



Best regards,

Charles


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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Bernd Neubig]

Tim Shoppa wrote:
>The Pierce logic-gate-biased-active oscillator is pretty reliable to start and 
>will oscillate somewhere with most crystals from kHz to MHz.
>As you found out, it will often come up on one of many overtones.
>To reduce chance of coming at an overtone, a series resistor from logic gate 
>output to the crystal is often enough. If not, a RC low-pass will cut down 
>even further (although of course adding phase shift.)

This is certainly the easiest and fastest way for a go/no-go test and to find 
the approximate resonance frequency. 
In the attached circuit diagram make CX1 and CX2 about 10 pF and RGK several 
MegOhms.
The inverter gate should be preferably an unbuffered HCMOS or other fast 
inverter.
For crystals in the MHz range you can replace RV by a short, for kHz crystals 
make it a few kOhms. If testing small watch crystals @ 32768 kHz or around, RV 
should be 100 kOhm at least. RV reduces the crystal drive level (RF current) to 
an acceptable level to avoid overloading or even damaging of the crystal. For 
low frequency crystals the RV-CX2 lowpass also avoids start-up at the overtone.
It is recommended to add a second inverter gate at the output to isolate your 
oscilloscope or counter input from the oscillator stage. Add some >330 ohm in 
series to the output of the 2nd inverter, if you connect a coaxial cable. Then 
terminate the coax at the oscilloscope or frequency counter end with 50 Ohms, 
so the square wave form will be roughly maintained.

In this circuit the crystal will not operate at its series resonance, but at a 
load resonance with load capacitance of something between 8 pF and 10 pF 
(depending on the inverter input and output capacitance plus the stray 
capacitances of your test fixture).
If you want to operate the oscillator at a (low) overtone, such as 3rd (or 
maybe 5th), you must add a series combination of 10 nF plus an inductor in 
parallel to CX2. The 10 nF is to avoid DC short-circuiting of the output. The 
inductor together with CX2 must have a resonance frequency mid between 
fundamental mode and 3rd overtone (not at one of them). So the tuned circuit 
acts like a capacitor at the 3rd OT and is inductive at fundamental mode (thus 
the phase condition for oscillation is not fulfilled at the fundamental mode)
Have fun

Bernd
DK1AG 
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Re: [time-nuts] HP 106a oscillator connectors question

[Dan Rae]

Corby wrote:


Need help identifying the RF connectors on the unit.
Corby, I may have some connectors on leads but would have to dig deep in 
my garage.  They were used a lot on some UK made Racal receivers in the 
sixties...


Let me know if you still need them.

Dan
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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Bruce Griffiths]

On reflection, building a jig to measure the crystal transmission as a function 
of frequency may be much easier than attempting to build an oscillator for an 
unknown crystal. However a suitable signal generator and detector are required.
Once the crystal parameters are known its much easier to design a suitable 
oscillator circuit. Measuring the location of spurious resonances may also be 
useful.

Bruce
 

On Saturday, 4 June 2016 9:52 PM, Bruce Griffiths 
 wrote:
 

 Some idea of the crystal equivalent circuit at the oscillation frequency would 
help considerably. Usually lower frequency crystals have a considerably higher 
series resistance than those operated at 1MHz or above.
At frequencies below 100kHz or so a Meacham bridge using something likke a 
wideband FET opamp may be feasible.
Bruce
 

On Saturday, 4 June 2016 9:01 PM, Mike Cook  wrote:
 

 Hi,

I have a number of crystals either in glass, bakelite, ceramic or metal 
housings that I would like to get resonating . They are of three basic types.
 Square, or rectangular flat  
 Round flat 
 Bar  square section
Sizes range from 2-10cm or more in the longest face.

Some have frequency markings. ranging from IKHz 5MHz. 
Others have none.
Some are of  Military origin, probably radios and as they have markings I can 
probably find a schematic from the radios to see how to proceed.  There may be 
dedicated testers still around. I am not so interested in this bunch at the 
moment. 
Others have no known origin so I have no idea what oscillator circuits were 
used with them. 
In terms of vintage, I would guess pre 1940  to late 50s 

I have built a little Pierce circuit an tried a few. Some of the later 1-5MHz 
crystals will oscillate but there are a lot of parasitic signals as well as the 
supposed fundamental. I cannot make any of the low frequency / big crystals to 
react.

So my question:
If you had a crystal with unknown frequency and drive requirements that you 
wanted to investigate. How would you go about it?

If I can get them going I will share the Adevs. I don’t have a spectrum 
analyser so I can’t do phase noise.

Regards

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Attila Kinali]

On Sat, 4 Jun 2016 10:46:40 +0200
Mike Cook  wrote:

> If you had a crystal with unknown frequency and drive requirements
> that you wanted to investigate. How would you go about it?

I would use some signal generator to generate a tunable sinusoid and
feed this to the quartz with the testing circuit from the standard
setup (see eg [1]) and measure the power on both sides of the quartz,
like in an VNA setup. You will probably not need the phase information,
so a simple power detector would be enough.

Bernd should be able to tell you way more about this than I can.

Attila Kinali

[1] "Load resonant measurements of quartz crystals", Dwane Rose, 1998
http://www.saunders-assoc.com/httpdocs/datasheets/paper/paper.pdf

-- 
Reading can seriously damage your ignorance.
-- unknown
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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Bruce Griffiths]

Some idea of the crystal equivalent circuit at the oscillation frequency would 
help considerably. Usually lower frequency crystals have a considerably higher 
series resistance than those operated at 1MHz or above.
At frequencies below 100kHz or so a Meacham bridge using something likke a 
wideband FET opamp may be feasible.
Bruce
 

On Saturday, 4 June 2016 9:01 PM, Mike Cook  wrote:
 

 Hi,

I have a number of crystals either in glass, bakelite, ceramic or metal 
housings that I would like to get resonating . They are of three basic types.
 Square, or rectangular flat  
 Round flat 
 Bar  square section
Sizes range from 2-10cm or more in the longest face.

Some have frequency markings. ranging from IKHz 5MHz. 
Others have none.
Some are of  Military origin, probably radios and as they have markings I can 
probably find a schematic from the radios to see how to proceed.  There may be 
dedicated testers still around. I am not so interested in this bunch at the 
moment. 
Others have no known origin so I have no idea what oscillator circuits were 
used with them. 
In terms of vintage, I would guess pre 1940  to late 50s 

I have built a little Pierce circuit an tried a few. Some of the later 1-5MHz 
crystals will oscillate but there are a lot of parasitic signals as well as the 
supposed fundamental. I cannot make any of the low frequency / big crystals to 
react.

So my question:
If you had a crystal with unknown frequency and drive requirements that you 
wanted to investigate. How would you go about it?

If I can get them going I will share the Adevs. I don’t have a spectrum 
analyser so I can’t do phase noise.

Regards

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] Mystery hp Ovens For Sale

[Bob Camp]

Hi

The “small” (less than a pound) 100 KHz crystals are not really great 
in terms of performance. If you get a GT (big thin square plate with attach 
right in the middle) they can have ok temperature performance. Because of 
their small size, their Q is relatively low and thus things like phase noise and
ADEV are not very good. 

Not accurate, but at least a hand waving sort of number:

If a high Q 5 MHz is 0.5” diameter *and* you did the same design at 
100 KHz, it’s going to be 25” in diameter. (Obviously not the way to do it). 

Bob

> On Jun 4, 2016, at 12:59 AM, Ian Stirling  wrote:
> 
>  It looks like the quartz is in the sealed glass "valve", or "tube".
> 
>  I have removed a similar glass vacuum enclosed 100 kHz frequency
> marker generator from my Eddystone EA12 receiver that I bought from
> Tom Roberts, G3YTO (SK 1985), in September 1978. I don't use the EA12
> any more and I wonder what kind of timing device I can make from this
> beautiful slab of quartz, approximately 28 x 5 x 2 mm. I don't have a
> data sheet for it, but I can see which pins are connected to the quartz.
> In the receiver, it has a spring stabilized black metal cover that mates
> to the socket. I suspect that is so that the thirteen valves and their
> heaters create a thermal equilibrium and the black shroud lets the
> crystal bathe in it. I ran the EA12 24/7 from then until I bought and
> used an IC-735 in January 1987.
> 
> It is a GEC Crystal Unit, 100 kHz, serial number 82690 and type JCF/193,
> "Made in England", and it looks like it means business.
> 
> Ian, G4ICV, AB2GR
> --
> 
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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Tim Shoppa]

With random old crystals in holders, it often helps to disassemble the
holder and clean crystal and holder plates with alcohol (my favorite back
in my youth was carbon tetracholoride but not so easy to find these days.)
I'm guessing most of your round blanks were for FT-243 type holders.

The Pierce logic-gate-biased-active oscillator is pretty reliable to start
and will oscillate somewhere with most crystals from kHz to MHz.

As you found out, it will often come up on one of many overtones.

To reduce chance of coming at an overtone, a series resistor from logic
gate output to the crystal is often enough. If not, a RC low-pass will cut
down even further (although of course adding phase shift.)

Many surplus crystals from the 50's will be marked with their series
resonant frequency. The military surplus tank crystals are marked with
channel number. By the 60's and 70's, crystals for VHF radios were often
marked with the channel frequency (that's after multiplication and mixing
with IF if a receive crystal.)

Tim N3QE

On Sat, Jun 4, 2016 at 4:46 AM, Mike Cook  wrote:

> Hi,
>
> I have a number of crystals either in glass, bakelite, ceramic or metal
> housings that I would like to get resonating . They are of three basic
> types.
>  Square, or rectangular flat
>  Round flat
>  Bar  square section
> Sizes range from 2-10cm or more in the longest face.
>
> Some have frequency markings. ranging from IKHz 5MHz.
> Others have none.
> Some are of  Military origin, probably radios and as they have markings I
> can probably find a schematic from the radios to see how to proceed.  There
> may be dedicated testers still around. I am not so interested in this bunch
> at the moment.
> Others have no known origin so I have no idea what oscillator circuits
> were used with them.
> In terms of vintage, I would guess pre 1940  to late 50s
>
> I have built a little Pierce circuit an tried a few. Some of the later
> 1-5MHz crystals will oscillate but there are a lot of parasitic signals as
> well as the supposed fundamental. I cannot make any of the low frequency /
> big crystals to react.
>
> So my question:
> If you had a crystal with unknown frequency and drive requirements that
> you wanted to investigate. How would you go about it?
>
> If I can get them going I will share the Adevs. I don’t have a spectrum
> analyser so I can’t do phase noise.
>
> Regards
>
> "The power of accurate observation is commonly called cynicism by those
> who have not got it. »
> George Bernard Shaw
>
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> time-nuts mailing list -- time-nuts@febo.com
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Bruce Griffiths]

A vector voltmeter can be replaced by a spectrum analyser or even a 14 bit 
scope with or without a preamp. In lieu of phase information one can measure 
the 3dB bandwidth to elicit the Q, combined with measurement of the low 
frequency shunt capacitance and the attenuation at resonance, the crystal 
parameters can be extracted without knowledge of the phase shift.
Bruce
  

On Saturday, 4 June 2016 11:01 PM, Bruce Griffiths 
 wrote:
 

 On reflection, building a jig to measure the crystal transmission as a 
function of frequency may be much easier than attempting to build an oscillator 
for an unknown crystal. However a suitable signal generator and detector are 
required.
Once the crystal parameters are known its much easier to design a suitable 
oscillator circuit. Measuring the location of spurious resonances may also be 
useful.

Bruce
 

    On Saturday, 4 June 2016 9:52 PM, Bruce Griffiths 
 wrote:
 

 Some idea of the crystal equivalent circuit at the oscillation frequency would 
help considerably. Usually lower frequency crystals have a considerably higher 
series resistance than those operated at 1MHz or above.
At frequencies below 100kHz or so a Meacham bridge using something likke a 
wideband FET opamp may be feasible.
Bruce
 

    On Saturday, 4 June 2016 9:01 PM, Mike Cook  wrote:
 

 Hi,

I have a number of crystals either in glass, bakelite, ceramic or metal 
housings that I would like to get resonating . They are of three basic types.
 Square, or rectangular flat  
 Round flat 
 Bar  square section
Sizes range from 2-10cm or more in the longest face.

Some have frequency markings. ranging from IKHz 5MHz. 
Others have none.
Some are of  Military origin, probably radios and as they have markings I can 
probably find a schematic from the radios to see how to proceed.  There may be 
dedicated testers still around. I am not so interested in this bunch at the 
moment. 
Others have no known origin so I have no idea what oscillator circuits were 
used with them. 
In terms of vintage, I would guess pre 1940  to late 50s 

I have built a little Pierce circuit an tried a few. Some of the later 1-5MHz 
crystals will oscillate but there are a lot of parasitic signals as well as the 
supposed fundamental. I cannot make any of the low frequency / big crystals to 
react.

So my question:
If you had a crystal with unknown frequency and drive requirements that you 
wanted to investigate. How would you go about it?

If I can get them going I will share the Adevs. I don’t have a spectrum 
analyser so I can’t do phase noise.

Regards

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Bob Camp]

Hi

Simple approach is to assume that you have a crystal resistance in the range of 
100K ohms. If you guess to 
high, the oscillator will just work to well :)

Multiple JFETS in cascade for the higher frequency stuff should work. For 
anything below 20 KHz, an op-amp
is likely your best bet.

A spectrum analyzer with a tracking generator will give you some idea of their 
impedance and *if* they still have 
any activity at all. 

Bob

> On Jun 4, 2016, at 4:46 AM, Mike Cook  wrote:
> 
> Hi,
> 
> I have a number of crystals either in glass, bakelite, ceramic or metal 
> housings that I would like to get resonating . They are of three basic types.
> Square, or rectangular flat   
> Round flat 
> Bar  square section
> Sizes range from 2-10cm or more in the longest face.
> 
> Some have frequency markings. ranging from IKHz 5MHz. 
> Others have none.
> Some are of  Military origin, probably radios and as they have markings I can 
> probably find a schematic from the radios to see how to proceed.  There may 
> be dedicated testers still around. I am not so interested in this bunch at 
> the moment. 
> Others have no known origin so I have no idea what oscillator circuits were 
> used with them. 
> In terms of vintage, I would guess pre 1940  to late 50s 
> 
> I have built a little Pierce circuit an tried a few. Some of the later 1-5MHz 
> crystals will oscillate but there are a lot of parasitic signals as well as 
> the supposed fundamental. I cannot make any of the low frequency / big 
> crystals to react.
> 
> So my question:
> If you had a crystal with unknown frequency and drive requirements that you 
> wanted to investigate. How would you go about it?
> 
> If I can get them going I will share the Adevs. I don’t have a spectrum 
> analyser so I can’t do phase noise.
> 
> Regards
> 
> "The power of accurate observation is commonly called cynicism by those who 
> have not got it. »
> George Bernard Shaw
> 
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