Re: Another Q-meter info source
Yes, I would like very much to see that article.
73 (Regards).
Max K 4 O D S.
I've Never Lost the Wonder.
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Jim Strohm Sent: Tuesday, August 30, 2022 5:02 PM To: [email protected]Subject: [Test Equipment Design & Construction] Another Q-meter info source Hi all The August 2022 QCWA newsletter has an article about Q-meter design. I haven't vetted it for accuracy, but it looks like it tells the truth. Knowing that not everybody here is a QCWA member ... if you'd like, I can share the article here, "for educational purposes only." Ask and ye probably will receive. 73 Jim N6OTQ
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Re: Cal Lab Magazine - International Journal of Metrology
The rule is that units named for people are not capitalized when
spelled out. That assures that "two watts" is a measure of power,
while "two Watts" refers refers to two family members.
A seeming exception is "degrees Celsius," but the unit name consists
of both words, and one does not capitalize degrees.
Abbreviations for units named after people are capitalized, however.
Thus, a capacitance may be reported as 10 nanofarads or 10 nF.
-- Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 8/30/2022 17:38, MAX wrote:
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This
matter of lower case for units has me wondering.? Ever since
I started my website I have been using a lower case f to
represent farads.? Recently I received an email from someone
who was retired from HP and its successor names correcting
me that a capitol F should be used for Farads.? In the pages
I have created since I have been using a capitol F as in pF,
nF, etc.? So who is right?
?
73
(Regards).
?
Max
K 4 O D S.
?
I've
Never Lost the Wonder.
?
From:
[email protected]
[mailto:[email protected]] On
Behalf Of Pete Harrison
Sent: Tuesday, August 30, 2022 2:39 AM
To: [email protected]
Subject: Re: [Test Equipment Design &
Construction] Cal Lab Magazine - International Journal of
Metrology
?
Thanks Dave.
I was also unaware of this . ive
subscribed and found a few interesting documents on the site.
?
regards Pete
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Re: Cal Lab Magazine - International Journal of Metrology
This matter of lower case for units has me wondering.? Ever since I started my website I have been using a lower case f to represent farads.? Recently I received an email from someone who was retired from HP and its successor names correcting me that a capitol F should be used for Farads.? In the pages I have created since I have been using a capitol F as in pF, nF, etc.? So who is right? ? 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 Pete Harrison
Sent: Tuesday, August 30, 2022 2:39 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Cal Lab Magazine - International Journal of Metrology ? Thanks Dave. I was also unaware of this . ive subscribed and found a few interesting documents on the site. ? regards Pete
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Re: Making a Q-meter / References etc
Thinking about it, there are 2 Pi radians in a complete cycle, so the ln(-2) being i Pi + ln(2) is showing a 180 degree phase shift. I tried computing the log base e of -2 i, which would be a 90 degree phase shift. That gives i Pi/2?+ ln(2).
I have never played with the logs of negative numbers before, but it does make some sense.
Dave
On Wed, 31 Aug 2022 at 00:19, Dr. David Kirkby < drkirkby@...> wrote: On Wed, 31 Aug 2022 at 00:15, Dr. David Kirkby < drkirkby@...> wrote: Further to the application of dB to inverting amplifiers. ? All of the calculators that I have checked this on, return an error message when the ratio (Vout/Vin) is negative.
I will show you a calculator that does not - see attached.
Oops, I forgot to attach the result of Mathematica computing the log base e, and the log base 10 of -2. I must admit, I can't make sense of that, but I'm not a mathematician!?
But thank you for making the spreadsheet available.
Dave
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Re: Making a Q-meter / References etc
On Wed, 31 Aug 2022 at 00:15, Dr. David Kirkby < drkirkby@...> wrote: Further to the application of dB to inverting amplifiers. ? All of the calculators that I have checked this on, return an error message when the ratio (Vout/Vin) is negative.
I will show you a calculator that does not - see attached.
Oops, I forgot to attach the result of Mathematica computing the log base e, and the log base 10 of -2. I must admit, I can't make sense of that, but I'm not a mathematician!?
But thank you for making the spreadsheet available.
Dave
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Re: Making a Q-meter / References etc
Further to the application of dB to inverting amplifiers. ? All of the calculators that I have checked this on, return an error message when the ratio (Vout/Vin) is negative.
I will show you a calculator that does not - see attached.
But consider a VNA connected to a wide-band amplifier with a gain of 10 dB. The output power is always 10 dB higher than the input. The VNA will show |S21| as 10 dB, irrespective of the phase shift through the amplifier. An inverted output is just a phase shift of 180 degrees. I would say the phase angle is irrelevant to the calculation of gain.
? When using a logarithmic ratio, a + prefix denotes a ratio greater than unity. And a – prefix a ratio of less than unity. By convention the prefix can be omitted if gain, or loss, is implied. I.E. the 100W amplifier had a power gain of 30dB, or the attenuator had a loss of 3.5dB. In both cases the prefix is implied in the description.
True, and in both cases, the phase of the output is irrelevant in computing the gain (or loss) in dB.
However, I do think people should use their common sense, and would enter two positive numbers, despite the phase being shifted 180 degrees.
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Re: Making a Q-meter / References etc
I am more concerned that the math is correct, the spreadsheet is use-able and has a fairly complete set of conversions as needed for the task.? Grammer is less important or adhesion to the latest standards bodies fine details, unless it makes the sheet so ambiguous it cannot be used.
Let's not spend all our time on nitpicking. It is Rodger's spreadsheet so let him decide how he wants to display the info. We are all free to take it and edit the spreadsheet to match our preferences or local languages. I don't think the intent is to publish this directly into something like an IEEE document.
Thanks Rodger for putting this together.
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Re: Another Q-meter info source
On Tue, 30 Aug 2022 at 23:02, Jim Strohm < jim.strohm@...> wrote: Hi all
The August 2022 QCWA newsletter has an article about Q-meter design.
I haven't vetted it for accuracy, but it looks like it tells the
truth.
Knowing that not everybody here is a QCWA member ... if you'd like, I
can share the article here, "for educational purposes only."
Ask and ye probably will receive.
73
Jim N6OTQ
That would be great.
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Re: Another Q-meter info source
Hi Steve
I'll send it to the group as an attachment, or see about putting it in
the files section. It's small enough that it shouldn't choke too many
peoples' mailboxes or connections.
Probably tomorrow.
73
Jim N6OTQ
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On Tue, Aug 30, 2022 at 5:07 PM Steve Ratzlaff <ratzlaffsteve@...> wrote:
Hi Jim,
Yes, I'm asking for a copy. :)
73,
Steve AA7U
On 8/30/2022 3:02 PM, Jim Strohm wrote:
Hi all
The August 2022 QCWA newsletter has an article about Q-meter design.
I haven't vetted it for accuracy, but it looks like it tells the
truth.
Knowing that not everybody here is a QCWA member ... if you'd like, I
can share the article here, "for educational purposes only."
Ask and ye probably will receive.
73
Jim N6OTQ
|
Another Q-meter info source
Hi all
The August 2022 QCWA newsletter has an article about Q-meter design.
I haven't vetted it for accuracy, but it looks like it tells the
truth.
Knowing that not everybody here is a QCWA member ... if you'd like, I
can share the article here, "for educational purposes only."
Ask and ye probably will receive.
73
Jim N6OTQ
|
Re: Making a Q-meter / References etc
Further to the application of dB to inverting amplifiers. ? All of the calculators that I have checked this on, return an error message when the ratio (Vout/Vin) is negative. ? When using a logarithmic ratio, a + prefix denotes a ratio greater than unity. And a – prefix a ratio of less than unity. By convention the prefix can be omitted if gain, or loss, is implied. I.E. the 100W amplifier had a power gain of 30dB, or the attenuator had a loss of 3.5dB. In both cases the prefix is implied in the description. ? Rodger Bean ?
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From: [email protected] <[email protected]> On Behalf Of Rodger Bean
Sent: Tuesday, 30 August 2022 13:35
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Making a Q-meter / References etc? Hi Dave, Thank you for the feedback, an amended version is attached. ? - The input power of watt is rounded to the nearest integer - it would be useful if it allowed a few decimal places, as entering powers in nW or similar is not unusual. But if I enter 1.4 W, it gets rounded to 1 in the input display, but the outputs are more sensible.
Done. (Working in the TV broadcast industry, most of the transmitters that I worked on were 100W up to 30KW). ? - You might consider whether it's worthwhile adding dbW. I know it's not used a lot, but our amateur licenses in the UK are specified in dBW now, not watt.
Done. - You say dBm is referenced to 1 mW, and dBuV is referenced to 1 uV, but for dBmV, you spell out the millivolt, rather than just put 1 mV.
Done. - You mention dBu, but don't allow anyone to perform any calculations with it.
For dBu, use 600Ω and ignore Watts, dBm, dBmV & dbuV. - There's a spelling error – impemdence.
- Done.
- According to the BIPM, the body that defines the SI standards, virtually all SI units and derived units should be spelled in lower case, and without the s - so watt, ampere, volt, not Watts, Volts, Amps etc. I think the only exception to this is degrees Celsius. (I have attached a copy of the SI document).
Just a personal preference. Re SI, having lived through: fps, cgs, MKS and SI. It’s all just numbers, although at least in emu & esu (electrostatic units & electromagnetic units) there was no π in a constant. And anyway, SI is just a collection of precisely defined, arbitrary units, relating to the an ordinary planet, orbiting around an ordinary star, in remote part of a galaxy that we call The Milky Way. They have as much in common with the rest of the universe as the distance from the thumb to the nose of whoever is the current reigning monarch. (lol). 7) If on the voltage gain section, I put an input of 1 V, and an output of -2 V, the calculator shows an error. Not so easy to fix, I could square V1 & V2 then square root them to remove the negative sign, but I don’t believe that it is necessary.? And any changes that gave a negative dB would imply a loss where none exists. There may be a function that only takes the modulus of a number entry. But I think it would be easier to remember that you are using an inverting amplifier. * It's easy to configure an op-amp to have a negative gain (inverting amplifier). * A VNA will often measure a reflected voltage that is 180 degrees out of phase with respect to the input. ? Rodger Bean ? ? ? That's useful. Can I suggest a few improvements? 1) The input power of watt is rounded to the nearest integer - it would be useful if it allowed a few decimal places, as entering powers in nW or similar is not unusual. But if I enter 1.4 W, it gets rounded to 1 in the input display, but the outputs are more sensible. 2) You might consider whether it's worthwhile adding dbW. I know it's not used a lot, but our amateur licenses in the UK are specified in dBW now, not watt. 3) You say dBm is referenced to 1 mW, and dBuV is referenced to 1 uV, but for dBmV, you spell out the millivolt, rather than just put 1 mV. 4) You mention dBu, but don't allow anyone to perform any calculations with it. 5) There's a spelling error - impemdence 6) According to the BIPM, the body that defines the SI standards, virtually all SI units and derived units should be spelled in lower case, and without the s - so watt, ampere, volt, not Watts, Volts, Amps etc. I think the only exception to this is degrees Celsius. (I have attached a copy of the SI document). 7) If on the voltage gain section, I put an input of 1 V, and an output of -2 V, the calculator shows an error. * It's easy to configure an op-amp to have a negative gain (inverting amplifier). * A VNA will often measure a reflected voltage that is 180 degrees out of phase with respect to the input. I personally would take the absolute magnitudes of the voltages and use that to calculate the gain, so as to not show an error when the input and output are of a different sign. 8) According to the BIPM, there should be a space between a number and a unit - ie 2 uV not 2uV. 9) You are inconsistent in your use of P1 and P 1, and likewise V2 and V 2. Personally I would remove the spaces, as spaces imply multiplication. Or perhaps consider the use of subscripts. 10) I think the last part is potentially wrong, if the DUT does not accept all the input power. If the device reflects a lot of power on the left hand side, then the input power can be high, the output power low, but the dissipation is also low. When calculating antenna gains, the values are in terms of power accepted by the antenna, not the input power to the antenna. I can think of two things you could usefully add. 1) The ability to calculate output voltages given an input voltage and a gain. 2) Noise temperature to noise figure and noise factor conversions. It looks like a useful calculator, but there are some random suggestions of mine. Dr David Kirkby Ph.D
Email: drkirkby@... Web:
Kirkby Microwave Ltd (Tel 01621-680100 / +44 1621-680100)
Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT.
? ? I created this Excel spreadsheet to convert between Watts, Volts, dBm, dBmV and dBuV. It has simple protection applied to guard against accidental overwriting of a formula. There is no password required to turn it off. To turn the protection off, got to “file” then “info”. ? Rodger Bean ? ? Well the box turned out a little silly, basically a short from BNC to BNC.
?I setup a series LC 230uh, 110pf (variable) I could not get a dip, (still unsure why, not my first rodeo)
So, I installed a better than 1%, 1Ω resistor as the DUT and used 50kHz to avoid any strays.
Using db on my HP 400E (unknown calibration) Using 1 volt input and 1Ω load, I get -26.45db with the db scale and using a voltage ratio 1/ 0.0371 = 26.95 = 28.6db
?I don't know why the printed scale would not be in agreement.
?The correct answer (according to the paper) is 28.3db, so pretty good agreement using the voltage ratio! The meter error difference is 1.3mv.
?My favorite db to voltage, voltage to db calculator.
? I received parts for another project, so this is now on the back burner, but will keep reading in case someone has ideas where I went wrong.
??????????????????????????????????????????? Thanks, Mikek
* After talking with a calibration facility, I sent my HP 400E in for calibration ($25 shipping) Then they told me, "we can't calibrate that"
?After I get my HP 3400 working properly, I'll check, I think that someone will be able to calibrate that.
>I decided to tighten it up and put the termination at the meter.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? Mikek ???????
?????????????????????????? ?
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Re: Wanted - moderator in a different timezone
On Mon, Aug 22, 2022 at 08:13 AM, Tam Hanna wrote:
In Austria and Swabia, people believe that what is written down might become true.
I can imagine some useful applications for this in the political sphere.
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Re: Making a Q-meter / References etc
At one time I did a lot of 3db frequency up/down from resonance Q measurements. To make it easy on myself,
I found that 5 / 7 = 0.714, that is so close to 0.707 that the difference is hard to read on a scope. So, I would
find resonance, set oscillator output (or use cal. adjust) to read 7 units on the scope, then go up in frequency
until I got 5 units, record frequency then go down in frequency until I got 5 units and record it. Then do the math.
This is especially good for relative measurements between coils.
?I do agree a scope does not good have good readability for high Q coils, it's even hard to get the frequency set on the Frequency generator.
If you have a Q of 1350 at 1MHz, that is approximately 370Hz on either side of resonance, and 20Hz makes a
difference in the scope reading, it's touchy. (most of my fun is in the AMBC band)
?????????????????????????????????? Mikek
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Re: Making a Q-meter / References etc
Add to:
Section "Single Voltage T50-2 37T #24 with 330pF C0G Q Measurement" is a
VNWA BW Q measurement of same T50-2 inductor and 330pF capacitor with
Q=236. Whereas, Oscilloscope Vrms method results with Q=203.
Having greater confidence in Bandwidth method, I question viability of
Oscilloscope RMS voltage measurement method for high Q devices.
Possibly a HF RMS voltmeter will have increased accuracy.
John KN5L
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On 8/29/22 8:09 AM, John KN5L wrote: Measurements using a single voltage measurement with an air coil may not
be easily reproducible. Air coil selected at the time for computing Q
using an online coil calculator.
is updated with easier to replicate Toroidal inductor, shown in section
"Single Voltage T50-2 37T #24 with 330pF C0G Q Measurement"
Signal generator is set to near maximum output to increase DUT Vout
measurement. Using Oscilloscope Averaging and RMS measure for greater
accuracy.
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Re: Making a Q-meter / References etc
I should have read further down on the page I quoted. The Style
Manual (2002:184) states:
The names of units do take a plural s when associated with
numbers greater than one. Examples given are: 1 kilogram but 25 kilograms; 1
metre, but 1.5 metres;
1 degree Celsius, but 15 degrees Celsius. However (2002:185)
hertz, lux and siemens remain unchanged in the plural: 10 kilohertz, 3 lux, 1.5
siemens
?
Cheers, Brian
?
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From: [email protected]
[mailto:[email protected]] On Behalf Of Tom
Lee
Sent: Tuesday, 30 August 2022 1:29 PM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Making a Q-meter
/ References etc
?
Thanks, but I already noted that explicitly in the first
paragraph of my post. My question is not about the symbols, but about
the units when spelled out. David asserted that the BIPM says that even
in that case, one does not add an s. I cannot find any reference to such a rule
in my search of BIPM docs.
--Tom
--
Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070
On 8/29/2022 20:15, Brian wrote:
The Style Manual, the Australian Government Publishing
Service document, states quite categorically that SI unit symbols never take a
plural s (Wiley Australia, 2002:184). This is based on ISO:31:1992.
Cheers,
Brian
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Re: Cal Lab Magazine - International Journal of Metrology
Thanks Dave.
I was also unaware of this . ive subscribed and found a few interesting documents on the site.
?
regards Pete
|
Re: Making a Q-meter / References etc
I would agree that "220 ohms" reads better in English than "220 ohm". But if you think about it, a 220 Ω resistor is not 220 resistors each of one ohm all joined up in series.
So is it really a plural? How about when the number is less than one (i.e. 0.44 Ω) ?
The correct answer is "the resistance is 220 ohms", and "I have five 220 ohm resistors". Standard English grammar, think about what the plural refers to: lots of ohms in the first case and the number of resistors in the second. Regards Jeff
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Re: Making a Q-meter / References etc
Thank you for looking into this, Dave. I appreciate it greatly. Your
post was very helpful in reminding me how many years it's been since
I updated my knowledge of the latest conventions.
I always learn a lot from your excellent posts.
-- Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 8/30/2022 00:36, Dr. David Kirkby,
Kirkby Microwave Ltd wrote:
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On Tue, 30 Aug 2022 at 04:29, Tom Lee < tomlee@...>
wrote:
Thanks, but I already noted that explicitly in the
first paragraph of my post. My question is not about the symbols,
but about the units when spelled out. David
asserted that the BIPM says that even in that case, one
does not add an s. I cannot find any reference to such a
rule in my search of BIPM docs.
--Tom
On checking, I can't find anything either. Perhaps I read
it elsewhere - an NPL document for example.
The SI document is searchable, and a search of volts,
watts, moles, amperes does not find any such words. However,
there are numerous references to newtons. On page 59 I read
"namely the value of 683 lumens per watt"
But then on page 76 it says
"is exactly
683 lumen per watt",? so again, no
s, despite the perceived plural. So both "683 lumens"
and "683 luman" are found. There does
seem to be some inconsistency
I would
agree that "220 ohms" reads better in English than "220
ohm". But if you think about it, a 220 Ω resistor is
not 220 resistors each of one ohm all joined up in
series. So is it really a plural?? How about when the
number is less than one (i.e. 0.44?
Ω)
??
This needs
a bit more research, as I'm sure I did not dream up this
thing about not adding an s on the end. But I admit it
not stated in the document I attached.
Dave
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Re: Making a Q-meter / References etc
Also the voltages do not state whether they are EMF or PD.
Regards
Jeff G8HUL
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Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Dr. David Kirkby, Kirkby Microwave Ltd Sent: 29 August 2022 22:35 To: [email protected]Subject: Re: [Test Equipment Design & Construction] Making a Q-meter / References etc That's useful. Can I suggest a few improvements? 1) The input power of watt is rounded to the nearest integer - it would be useful if it allowed a few decimal places, as entering powers in nW or similar is not unusual. But if I enter 1.4 W, it gets rounded to 1 in the input display, but the outputs are more sensible. 2) You might consider whether it's worthwhile adding dbW. I know it's not used a lot, but our amateur licenses in the UK are specified in dBW now, not watt. 3) You say dBm is referenced to 1 mW, and dBuV is referenced to 1 uV, but for dBmV, you spell out the millivolt, rather than just put 1 mV. 4) You mention dBu, but don't allow anyone to perform any calculations with it. 5) There's a spelling error - impemdence 6) According to the BIPM, the body that defines the SI standards, virtually all SI units and derived units should be spelled in lower case, and without the s - so watt, ampere, volt, not Watts, Volts, Amps etc. I think the only exception to this is degrees Celsius. (I have attached a copy of the SI document). 7) If on the voltage gain section, I put an input of 1 V, and an output of -2 V, the calculator shows an error. * It's easy to configure an op-amp to have a negative gain (inverting amplifier). * A VNA will often measure a reflected voltage that is 180 degrees out of phase with respect to the input. I personally would take the absolute magnitudes of the voltages and use that to calculate the gain, so as to not show an error when the input and output are of a different sign. 8) According to the BIPM, there should be a space between a number and a unit - ie 2 uV not 2uV. 9) You are inconsistent in your use of P1 and P 1, and likewise V2 and V 2. Personally I would remove the spaces, as spaces imply multiplication. Or perhaps consider the use of subscripts. 10) I think the last part is potentially wrong, if the DUT does not accept all the input power. If the device reflects a lot of power on the left hand side, then the input power can be high, the output power low, but the dissipation is also low. When calculating antenna gains, the values are in terms of power accepted by the antenna, not the input power to the antenna. I can think of two things you could usefully add. 1) The ability to calculate output voltages given an input voltage and a gain. 2) Noise temperature to noise figure and noise factor conversions. It looks like a useful calculator, but there are some random suggestions of mine. Dave Dr David Kirkby Ph.D Email: drkirkby@... <mailto:drkirkby@...> Web: Kirkby Microwave Ltd (Tel 01621-680100 / +44 1621-680100) Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT. On Mon, 29 Aug 2022 at 20:45, Rodger Bean <rodgerbean@... <mailto:rodgerbean@...> > wrote: I created this Excel spreadsheet to convert between Watts, Volts, dBm, dBmV and dBuV. It has simple protection applied to guard against accidental overwriting of a formula. There is no password required to turn it off. To turn the protection off, got to “file” then “info”. Rodger Bean From: [email protected] <mailto: [email protected]> < [email protected] <mailto: [email protected]> > On Behalf Of Mikek Sent: Tuesday, 30 August 2022 00:36 To: [email protected] <mailto: [email protected]> Subject: Re: [Test Equipment Design & Construction] Making a Q-meter / References etc Well the box turned out a little silly, basically a short from BNC to BNC. I setup a series LC 230uh, 110pf (variable) I could not get a dip, (still unsure why, not my first rodeo) So, I installed a better than 1%, 1Ω resistor as the DUT and used 50kHz to avoid any strays. Using db on my HP 400E (unknown calibration) Using 1 volt input and 1Ω load, I get -26.45db with the db scale and using a voltage ratio 1/ 0.0371 = 26.95 = 28.6db I don't know why the printed scale would not be in agreement. The correct answer (according to the paper) is 28.3db, so pretty good agreement using the voltage ratio! The meter error difference is 1.3mv. My favorite db to voltage, voltage to db calculator. I received parts for another project, so this is now on the back burner, but will keep reading in case someone has ideas where I went wrong. Thanks, Mikek * After talking with a calibration facility, I sent my HP 400E in for calibration ($25 shipping) Then they told me, "we can't calibrate that" After I get my HP 3400 working properly, I'll check, I think that someone will be able to calibrate that. >I decided to tighten it up and put the termination at the meter. Mikek < /g/Test-Equipment-Design-Construction/attachment/306/0/Q%20Tester%20tightened%20up.jpg>
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Re: Making a Q-meter / References etc
On Tue, 30 Aug 2022 at 04:35, Rodger Bean < rodgerbean@...> wrote: Hi Dave, Thank you for the feedback, an amended version is attached.
You are welcome.?
? - According to the BIPM, the body that defines the SI standards, virtually all SI units and derived units should be spelled in lower case, and without the s - so watt, ampere, volt, not Watts, Volts, Amps etc. I think the only exception to this is degrees Celsius. (I have attached a copy of the SI document).
Just a personal preference. Re SI, having lived through: fps, cgs, MKS and SI. It’s all just numbers, although at least in emu & esu (electrostatic units & electromagnetic units) there was no π in a constant. And anyway, SI is just a collection of precisely defined, arbitrary units, relating to the an ordinary planet, orbiting around an ordinary star, in remote part of a galaxy that we call The Milky Way. They have as much in common with the rest of the universe as the distance from the thumb to the nose of whoever is the current reigning monarch. (lol).
I wrote about this earlier, so I won't repeat it.?
7) If on the voltage gain section, I put an input of 1 V, and an output of -2 V, the calculator shows an error. Not so easy to fix, I could square V1 & V2 then square root them to remove the negative sign, but I don’t believe that it is necessary.? And any changes that gave a negative dB would imply a loss where none exists. There may be a function that only takes the modulus of a number entry. But I think it would be easier to remember that you are using an inverting amplifier.
It would be easy to fix - use the abs() function. I agree that giving a negative dB would be incorrect, but personally I would say an input voltage of 1 V, and an output of -2 V, would be a gain of 6 dB, not an error.
Dave
|
Dr. David Kirkby, Kirkby Microwave Ltd
Brian