Pearson and Ion Physics make CT’s suitable for RF applications. Some have a rise time as short as 2ns (=>500MHz). Some are expensive though. ? See Pearson’s website at ? Not sure if Ion Physics is still in business. ? I have a couple of Pearson units and they are very well make. ? Cheers, George VK2KGG ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Tom, wb6b
Sent: Friday, 2 September 2022 12:08 PM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] RF Current meters ? Following this thread with interest.
I would probably try a low value chip resistor epoxied to a thermistor. The resistor would be in series with the center lead of the coax. With a little thermal isolation. I don't think a resistor in series in the RF circuit would be significantly more lossy than current transformers or other methods of measuring RF current. Maybe even better than other methods.?
The advantage of the chip resistor would be frequency range and true RMS readings.
You could put a second resistor/thermistor that you control a D.C. current into and make a bridge if you wanted to be really accurate. Otherwise just let a microprocessor do a curve fit on a single resistor/thermistor against another ambient temperature reading.
Interesting about the indirect temperature measurement ideas. Here is a link from a quick search. I'm sure there are other, maybe better, choices with a little more searching. There are far infrared sensors with digital interfaces (I2C), too.
The wavelengths used for non-contact temperature measurement seem to be around the?8 ?m to 14 ?m range.
Tom, wb6b
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On Fri, 2 Sep 2022 at 00:40, John Kolb < jlkolb@...> wrote:
Even if you could get accurate measurements with the limited contact
area, you would still be faced with the slow response time of a glass
thermometer.? Makes adjustments difficult.
Agreed
I like the idea of a fixed gain amplifier and diode detector directly
measuring the voltage across the 0.02 or whatever ohm resistor.
That requires making and calibrating an RF volt meter. I don’t know the what sort of accuracy one could achieve with that, but I don’t have any obvious ways of checking that. If that resistor was 10 m ohm, which was the sort of value I was hoping to use, a 50 ohm power meter would cause negligible loading. But RF lower measurements are tricky, and achieving a 2% uncertainty is tricky. Neither my RF power meter no the 10 MHz to 18 GHz sensors are calibrated. At least a thermal method can be calibrated with DC substitution. I suspect that my uncertainty of a thermal method would be lower than I achieve with an RF volt meter.?
I am interested in making the overall uncertainty of Q measurements as low as possible - not because I have a need for a low uncertainty, but because it would be interesting to do the best job possible.
John
Dave? -- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@...Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
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Re: Cal Lab Magazine - International Journal of Metrology
:)
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/1/2022 21:06, Orin Eman wrote:
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On Thu, Sep 1, 2022 at 1:05
AM Tom Lee < tomlee@...>
wrote:
You'd not say "a 2 watts light
bulb" though, would you?
Of course not, which is why my example, the entirety of
which is delimited with quote marks, does not contain an
adjectival clause. You seem to have lost track of the
topic of discussion, which was the claim that there was
language in an official document proscribing the use of
pluralizations of units. No such documentation has been
found. Now you seem to think that I was asserting that one
must always pluralize units or some such
thing. I've made no such assertion, but if you want to
continue along those lines, I recommend a visit to the
Argument Clinic.
No, I only paid for five minutes.
Orin.?
|
Re: Cal Lab Magazine - International Journal of Metrology
On Thu, Sep 1, 2022 at 1:05 AM Tom Lee < tomlee@...> wrote:
You'd not say "a 2 watts light bulb" though,
would you?
Of course not, which is why my example, the entirety of which is
delimited with quote marks, does not contain an adjectival clause.
You seem to have lost track of the topic of discussion, which was
the claim that there was language in an official document
proscribing the use of pluralizations of units. No such
documentation has been found. Now you seem to think that I was
asserting that one must always pluralize units or
some such thing. I've made no such assertion, but if you want to
continue along those lines, I recommend a visit to the Argument
Clinic.
No, I only paid for five minutes.
Orin.?
|
On Thu, Sep 1, 2022 at 04:33 PM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
I have just ordered a couple of cheap IR photodiodes from RS
?
?
It would be interesting to try these IR photodiodes with a very small lightbulb as the current sensor, where the measured current just brings the filament to the dull red glowing range. Wonder if the increasing resistance with temperature of the filament would be an issue. Possibility causing the filament output to go from barely readable (under range) to bright glow (and over range) over a small current range. Or if operating at the "low" (barely glowing) filament temperatures would mitigate that. Sounds interesting to experiment with.? Tom, wb6b
|
Following this thread with interest. I would probably try a low value chip resistor epoxied to a thermistor. The resistor would be in series with the center lead of the coax. With a little thermal isolation. I don't think a resistor in series in the RF circuit would be significantly more lossy than current transformers or other methods of measuring RF current. Maybe even better than other methods.? The advantage of the chip resistor would be frequency range and true RMS readings. You could put a second resistor/thermistor that you control a D.C. current into and make a bridge if you wanted to be really accurate. Otherwise just let a microprocessor do a curve fit on a single resistor/thermistor against another ambient temperature reading. Interesting about the indirect temperature measurement ideas. Here is a link from a quick search. I'm sure there are other, maybe better, choices with a little more searching. There are far infrared sensors with digital interfaces (I2C), too.
The wavelengths used for non-contact temperature measurement seem to be around the?8 ?m to 14 ?m range.
Tom, wb6b
|
Re: Cal Lab Magazine - International Journal of Metrology
And the character map has been around quite a long time, at least
since windows 98SE.
--Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/1/2022 19:43, MAX wrote:
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Interesting.?
I counted 159 pages of characters.? There seems to be
anything that I could imagine and quite a few I couldn’t.
?
73
(Regards).
?
Max
K 4 O D S.
?
I've
Never Lost the Wonder.
?
From:
[email protected]
[mailto:[email protected]] On
Behalf Of Chuck Moore via groups.io
Sent: Thursday, September 01, 2022 10:29 AM
To: [email protected]
Subject: Re: [Test Equipment Design &
Construction] Cal Lab Magazine - International Journal of
Metrology
?
While it is not
beneath me to castigate Mr. Gates and his pox called Windows,
there is one redeeming quality they do not discuss openly, or
at least do not
seem to publicize all that frequently.
In Windows 10, where you click on the 'Start' menu, to the
right of the menu
icon, you should see, "Type here to search'. In that space
enter the text
string, "charmap".? You can press the "Enter" key or left
click the displayed
app "Character Map".
A popup screen will appear with an abundance of symbols.
Scroll through
until you find the symbol of interest. Symbols such as ?, ?,
?, ?, Δ, μ? can
be selected, copied and then pasted into pretty much any
Windows app
which allows user input.
|
Re: Cal Lab Magazine - International Journal of Metrology
Interesting.? I counted 159 pages of characters.? There seems to be anything that I could imagine and quite a few I couldn’t. ? 73 (Regards). ? Max K 4 O D S. ? I've Never Lost the Wonder. ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Chuck Moore via groups.io
Sent: Thursday, September 01, 2022 10:29 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Cal Lab Magazine - International Journal of Metrology ? While it is not beneath me to castigate Mr. Gates and his pox called Windows,
there is one redeeming quality they do not discuss openly, or at least do not
seem to publicize all that frequently.
In Windows 10, where you click on the 'Start' menu, to the right of the menu
icon, you should see, "Type here to search'. In that space enter the text
string, "charmap".? You can press the "Enter" key or left click the displayed
app "Character Map".
A popup screen will appear with an abundance of symbols. Scroll through
until you find the symbol of interest. Symbols such as ?, ?, ?, ?, Δ, μ? can
be selected, copied and then pasted into pretty much any Windows app
which allows user input.
|
We use a LISN is to provide isolation from other devices on the power system (low pass filter) and present a repatable power system line impedance so devices (both emitters and susceptors) can be later compared for compatibility. Equipment will react differently when connected to lines with diffrent impedances, so the goal is to standardize so that results can be meaningfully compared even when equipment is tested in different labs with different looking power systems. Generally the goal is to find equipment that will have about a 10 db margin between noise emitted from the emitter equipment and the amount of noise that must be injected onto the poewer system to cause undesierable function of susceptor equipment.
If the goal of testing all of the devices in your house is to reduce, eliminate or simply identify sources of conducted emissions (perhaps for the purposes of reducing noice floor on shortwave radio, measurement reciever or lab equipment), then you should be able to just build a coupling device to allow you to connect at a common point in your home near to the point of the susceptor(s). This coupling device would be connected to a spectrum analyzer sweeping the concerned spectrum and comparing changes as different equipment is switched on and off and operated under different modes of operation.
My radio station / electronics lab has a step down transformer feeding a EMI filter, feeding a local distribution panel, and I have had plans to do exactly this. The panel is located in close proximity to all devices where EMC is of concern add therefore all line impedances will be relatively equal, especially comparted to the rather larger line impedance presented by having the transformer and EMI filter at the common point (on the feeder) of the circuit. The benefit of this arrangement is that the test is performed in-place, on the actual power distribution system, and the emissions measured are actual and not just representative.
if the purpose of building a LISN is for pre-compliance testing, then you obviously will want a LISN that matches the line impedance of the standard by which you will ultimately be tested against.?
Greg
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Richard Brown was not a linguist.
'Philosophy' comes from Greek: 'philo' to love and 'sophos', wisdom. Today, philosophy means 'love of wisdom / knowledge'.
'Metrology' also comes from Greek: 'metro' to measure and 'logos', word. Today, metrology is 'words about measurement'.
So, while Richard Brown's hypothesis (If ...) contains falsehoods, John's conclusion is possibly correct. However, it's a non-sequitur.
73 de Brian, VK2GCE, scientist, writer, designer and builder of test equipment for the last 45 years.
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of John KN5L Sent: Friday, 2 September 2022 7:06 AM To: [email protected]Subject: [Test Equipment Design & Construction] Metrology Today I found: Specifically, Richard Brown, NPL’s Head of Metrology explains: “If philosophy is ‘thinking about thinking’, then metrology is ‘measuring measurement’.” In short, many people do measurement, but few do metrology. Little did I know my hobby, for the past six years years or so, has been metrology. My endeavors have been to validate measurements by making same measurement using different methods, instruments, or modeling and evaluating difference. My quest is three different methods or models. Also helps to have independent verification of measurements. Nice to have a list with similar interests, John KN5L
|
I’d use a current transformer, with a suitable detector. The detector could be a simple rectifier, or a nice logarithmic power meter, such as one based on an AD8307.
The article below includes the design of a CT that produces about 5 V/A into 50 ohms from 0.2-170 MHz, -3 dB.
Gary NA6O?
|
Even if you could get accurate measurements with the limited contact area, you would still be faced with the slow response time of a glass thermometer. Makes adjustments difficult.
I like the idea of a fixed gain amplifier and diode detector directly measuring the voltage across the 0.02 or whatever ohm resistor.
John
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On 9/1/2022 3:33 PM, Jeff Green wrote: Could you place nichrome wire against the bulb of an alcohol thermometer?
The alcohol should have no appreciable effect on inductance.
_._,_._,_
------------------------------------------------------------------------
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Could you place nichrome wire against the bulb of an alcohol thermometer?
The alcohol should have no appreciable effect on inductance.
Yes, in principle. although only a small area would be in contact with the glass. The other problem is that its not possible to easily get the data in a electronic (digital or analog) format.?
I have just ordered a couple of cheap IR photodiodes from RS
I bought one to try, and another to see it was possible to use it as an avalanche photodiode (APD). Not that I particularly need an APD, but I wondered if it might work in avalanche?mode. They were cheap enough to not worry about the cost.?
-- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@...Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
|
Today I found:
Specifically, Richard Brown, NPL’s Head of Metrology explains: “If
philosophy is ‘thinking about thinking’, then metrology is ‘measuring
measurement’.” In short, many people do measurement, but few do metrology.
Little did I know my hobby, for the past six years years or so, has been
metrology. My endeavors have been to validate measurements by making
same measurement using different methods, instruments, or modeling and
evaluating difference. My quest is three different methods or models.
Also helps to have independent verification of measurements.
Nice to have a list with similar interests,
John KN5L
|
Re: Cal Lab Magazine - International Journal of Metrology
On 2022-09-01 11:29 a.m., Chuck Moore via groups.io wrote: While it is not beneath me to castigate Mr. Gates and his pox called Windows,
there is one redeeming quality they do not discuss openly, or at least do not
seem to publicize all that frequently.
In Windows 10, where you click on the 'Start' menu, to the right of the menu
icon, you should see, "Type here to search'. In that space enter the text
string, "charmap".? You can press the "Enter" key or left click the displayed
app "Character Map". In OS X the equivalent feature exists, if you enable it in System Prefs -> Keyboard. ("Show keyboard and emoji viewers in menu bar") Then click the icon in top right of the menu bar, leading to Emoji & Symbols or Keyboard Viewer, both of which allow entry of Unicode symbols including all those discussed here. ...I use this quite a lot. Or of course you can learn the (shift)option sequences which haven't changed since 1983. --Toby A popup screen will appear with an abundance of symbols. Scroll through
until you find the symbol of interest. Symbols such as ?, ?, ?, ?, Δ, μ? can
be selected, copied and then pasted into pretty much any Windows app
which allows user input.
|
The sensors that Barry Chambers is
using for 30 THz comms testing are relatively low cost Melexis
single pixel IR bolometers.? The 90614 is good enough to detect
the thermal radiation from the Moon and is calibrated for
temperatures from -170 to +380 °C and compensated for a wide range
of device temperatures.? It has a resolution of 0.02 °C and could
probably be used to monitor the temperature of an 0603 or 0402
load resistor.? Might need a germanium or similar longwave IR lens
if the load resistor is to small to fill the sensor active area.
Other models have onboard DSP filtering
and multi-zone sensors.? Base models are around ?30 in 1-off.
--
|
Sigma Aldrich sell quantum dots in
various sizes, mostly in the optical range though.
CdSe/ZnS core-shell type quantum dots,
stabilized with octadecylamine ligands, fluorescence λem?540?nm,
solid
10 mg for a mere ?330.? Plus VAT
Cheap at twice the price.....
Neil G4DBN
On 01/09/2022 16:37, Wilko Bulte wrote:
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Vary the size of the quantum hole? You call Heisenberg. Or maybe Schr?dinger, I forgot.
?
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Vary the size of the quantum hole? You call Heisenberg. Or maybe Schr?dinger, I forgot.
?
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Re: Cal Lab Magazine - International Journal of Metrology
Actually, puff is quite common here in the Netherlands. So we align with the Brits here ?
Wilko
|
Re: Cal Lab Magazine - International Journal of Metrology
While it is not beneath me to castigate Mr. Gates and his pox called Windows,
there is one redeeming quality they do not discuss openly, or at least do not
seem to publicize all that frequently.
In Windows 10, where you click on the 'Start' menu, to the right of the menu
icon, you should see, "Type here to search'. In that space enter the text
string, "charmap".? You can press the "Enter" key or left click the displayed
app "Character Map".
A popup screen will appear with an abundance of symbols. Scroll through
until you find the symbol of interest. Symbols such as ?, ?, ?, ?, Δ, μ? can
be selected, copied and then pasted into pretty much any Windows app
which allows user input.
|
Dr. David Kirkby, Kirkby Microwave Ltd
Brian
John Kolb