This happens to be exactly what a circuit I am currently working on (should) do. My circuit is not as simple; the chip count is 17. If it
works and meets my design objective, frequency comparison will be better than 1e-11. If all goes perfectly, 1e-12 will be achieved. If that happens, I will substitute 3 74AHC chips for 74HC to get into the 1e-13 area. That might be a bit better than what you are looking for but part of the core circuitry is a Time-to-Amplitude converter (TAC). Commercial TACs resolve 10 pS for arbitrary time differences; I am restricting myself to 10 MHz and might do a bit better. I divide the 2 input frequencies by a factor of 1e8 to get a 0.1 Hz output, which is trued up (made synchronous with the input) with a gate. Both channels are identical. The first one to reach the end point starts the TAC, the purpose of which is to interpolate the time difference between the end points of the 2 channels. The astute reader will note that the start points will not be identical; there are several ways of taking care of this - the most straightforward of which is to use the TAC at the start points as well. My circuit (if it works) will get around this with some analog magic. The output is bipolar (the polarity of the analog output depende upun which frequency is higher.
I am not done yet; but the project is currently active.
I hope I've given you a good idea of how it works. Anyway, check to see of a TAC can be used to accomlish what you need. Full documentation will take a while.
Stephen Menasian
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A typo, I've measured a T68-6 23T #20 .....
John KN5L
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On 9/9/22 6:50 AM, John KN5L wrote: Hi Guido,
I've measured a T68-2 23T #20, as it's documented within Micrometals
Q-Curve document. Using methods described in Jacques' Q publication.
Lab notes:
John KN5L
On 9/8/22 6:18 PM, Guido ON7CH wrote:
John,
I was measuring a T68-yellow? 2.35uH.
The Q should be 260 @? 12.5MHz
The pictures are (for the moment) only for information. No calibration.
It was ment to give an idee of the? UI.
Guido? on7ch
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Hi Guido,
I've measured a T68-2 23T #20, as it's documented within Micrometals
Q-Curve document. Using methods described in Jacques' Q publication.
Lab notes:
John KN5L
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Show quoted text
On 9/8/22 6:18 PM, Guido ON7CH wrote: John,
I was measuring a T68-yellow? 2.35uH.
The Q should be 260 @? 12.5MHz
The pictures are (for the moment) only for information. No calibration.
It was ment to give an idee of the? UI.
Guido? on7ch
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Re: 10 MHz reference inputs
It makes for the need to drive these units with a form of buffer amplifier if connected to an external ?frequency source should the unit revert to internal reference in an unknown fashion.? But that doesn't preclude the possibility of doing harm to circuitry should either the unit or external driver not liking what it sees coming at it
?
It surprises me that considerations weren¡¯t given in the hardware design cycle to alleviate a problem such as this to prevent driving the internal reference back out into a external source.? If a unit is currently still being manufactured and sold and it possesses such a problem it might be worth contacting the manufacturer to alert them to the issue.? Given available firmware updates they might just fold the revision into the next issue.
?
Neil, I wonder if the 8562A does automatic external reference detect and switches appropriately.? If it requires manual switching the unit may also store the setting in NVRAM when powered down.?
?
Greg
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John,
I was measuring a T68-yellow? 2.35uH.
The Q should be 260 @? 12.5MHz
The pictures are (for the moment) only for information. No calibration.
It was ment to give an idee of the? UI.
Guido? on7ch
?
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Hi Gido,
Can you describe what was being measured?
I've measured T50-2 37T #24 using VNWA S21 method. Sweep is added to:
John KN5L
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On 9/8/22 3:50 PM, Guido ON7CH wrote: hereby an attempt to build a simple Q_METER for the DIY radio amateur.
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hereby an attempt to build a simple Q_METER for the DIY radio amateur.
Guido? on7ch
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Mikek wrote
?? > Do you remember the bandwidth?
core usable up to 80MHz......
??? > Do you have a constant voltage driver circuit?
No, straight 50 ohm generator
??? >? I added English titles to your diagram, using Google translate, (even though they were pretty easy to figure out).
Tanks Mikek
Two? different models
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Adrian,
both assumptions are correct
It must be heat resistant, the cupper housing is soldered tightly together.
the lowest possible internal resistance
Guido
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Re: 10 MHz reference inputs
HP8562A for example?
Neil G4DBN
On 08/09/2022 18:37, Greg Muir via
groups.io wrote:
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What piece of equipment do you have that puts the 10 MHz reference
back out of the external input jack when on internal mode?? I have
a large number of units that are locked to my lab standard through
a distribution amp but they all have separate input/output jacks.?
Have never seen one jack used for both.
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Re: 10 MHz reference inputs
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On Thu, Sep 8, 2022 at 11:38 AM Greg Muir via <big_sky_explorer= [email protected]> wrote: What piece of equipment do you have that puts the 10 MHz reference back out of the external input jack when on internal mode?? I have a large number of units that are locked to my lab standard through a distribution amp but they all have separate input/output jacks.? Have never seen one jack used for both.
Greg
-- K1FZY (WA4TPW) SK? 9/29/37-4/13/15
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Re: 10 MHz reference inputs
file:///C:/Users/kc6et/Downloads/DG1000Z_DataSheet.pdf?? Note the single In/Out BNC for reference.
On Thu, Sep 8, 2022 at 11:38 AM Greg Muir via <big_sky_explorer= [email protected]> wrote: What piece of equipment do you have that puts the 10 MHz reference back out of the external input jack when on internal mode?? I have a large number of units that are locked to my lab standard through a distribution amp but they all have separate input/output jacks.? Have never seen one jack used for both.
Greg
-- K1FZY (WA4TPW) SK? 9/29/37-4/13/15
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Do you remember the bandwidth?
?Do you have a constant voltage driver circuit?
I added English titles to your diagram, using Google translate, (even though they were pretty easy to figure out).
??? Mikek
?
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Re: 10 MHz reference inputs
What piece of equipment do you have that puts the 10 MHz reference back out of the external input jack when on internal mode?? I have a large number of units that are locked to my lab standard through a distribution amp but they all have separate input/output jacks.? Have never seen one jack used for both.
Greg
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> Hereby the construction principe of an Injection Transformer (50/1) that was made in a club project for a DIY Q-meter. Do you know why the primary was wound with wire-wrap wire (presumably the ptfe-insuilated 30 awg type) rather than ordinary enamelled copper wire ? Perhaps because it's silver plated ?
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Hereby the construction principe of an Injection Transformer (50/1) that was made in a club project for a DIY Q-meter.
Sorry for the markings in Dutch.
Guido? on7ch
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Added a high Q DUT measurement to:
This DUT was recently measured using VNWA bandwidth method. Prototype Q
Meter is measuring high again.
Function Generator output adjusted for 1V RF, full scale on VOM
High Q DUT required 1Hz frequency adjustment for peaking.
My hunch is RF voltmeter needs to be soldered up and mounted into a
shielded enclosure before any additional evaluations.
John KN5L
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On 9/8/22 7:49 AM, John KN5L wrote: Added to:
Is an Injection Transformer Q Meter prototype.
The RF voltmeter gain of 2.5 allows easy scaling on a 2.5V scale VOM.
Function Generator is set to 100mV out, which results with full scale Q
= 500.
RF Voltmeter was rechecked with VOM for linearity, it is.
Measured DUT Q = 300. Which seems high, I had expected something close
to 200.
DG1032 has resolution down into HZ digits, very easy to peak measurement.
John KN5L
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Added to:
Is an Injection Transformer Q Meter prototype.
The RF voltmeter gain of 2.5 allows easy scaling on a 2.5V scale VOM.
Function Generator is set to 100mV out, which results with full scale Q
= 500.
RF Voltmeter was rechecked with VOM for linearity, it is.
Measured DUT Q = 300. Which seems high, I had expected something close
to 200.
DG1032 has resolution down into HZ digits, very easy to peak measurement.
John KN5L
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Re: 10 MHz reference inputs
Has anyone used this SV1AFN distribution amplifier?
<>
Mike N2MS
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On 09/07/2022 9:19 AM Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@...> wrote:
On Tue, 6 Sep 2022 at 19:22, david vanhorn <kc6ete@...> wrote:
I'm fighting a problem with some signal generators and I thought this group might have some information I need.
1: For a "typical instrument" what level should the 10 MHz input be? These SGs say NOTHING in the manual about that.
2: My past experience with older HP/Tek gear is that if you provide an input they use that, otherwise they use their internal. I've seen instruments that have 10MHz input and output connectors separately, but now I'm faced with a new twist, a single connector marked 10 MHz In/Out These units let you manually select ext or internal, but if the ref goes away for a moment, or the power is lost, the SG switches back to internal without notifying you, AND forces it's internal 10 MHz out on the cable, which distorts and beats against the 10 MHz being supplied, potentially screwing up any other instruments on that feed! Isolated outputs is desirable. If you look on the time-nuts list you will see people aiming for around 100 dB isolation. Isolated BNC or TNC connectors are Low phase noise is desirable too if you are into metrology grade measurements.
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