On Fri, 12 Aug 2022 at 17:29, Tam Hanna < tamhan@...> wrote:
Hi,
do NOT use JavaScript for something so complex.
WebAssembly allows you to use a real programming language. You
can, for example, use C# and the Uno Framework, and then get a
WebAssembly output web page which can run in ANY web browser, even
on Linux and Mac OS.
Tam
It's not so complex - just tedious. I attach the specifications from the 4285A LCR meter manual. On page 8 it describes how to work out the accuracy. On page 9 you see equations for A1, A2, A3 ....A16. But only one of those is relevant. To determine what one is applicable you have to look at the graphs on pages 11 and 12. Then there's a cable length factor Ac, which depends on the length of the cables and frequency. There are other factors N1 and N2 which depend on frequency.? Another factor depends on temperature. Once you know all these factors you can work out accuracy of inductance, capacitance resistance etc. Then to work out Q you have to apply more formulas, and factors which depend on the indicated Q.
It basically becomes a big tedious mess. I would like a web page that does those calculations for the 4284A and 4285A.
Keysaid said they would consider having a spreadsheet for the newer meter. If they did that, I could probably hack it for my older meters.
I thought Javascript would be the way to create a webpage, although I admit my knowledge of web design does not extend beyond HTML and a bit of CSS. You mentioned not to use that, but use WebAssembly
According to Wikipedia at least
in the limitations section, the first item mentioned is
"
In general, WebAssembly does not allow direct interaction with the . All interaction must flow through JavaScript interop."
So it seems I would need JavaScript anyway. I might as well do the rest in JavaScript, as I don't think the problem is sufficiently complicated that I would really warrant using a lange and toolset I dont know.
Dave
|
Re: Flow calorimeter for RF/Microwave power measurement
Thanks Jeff, that's interesting about
the temperature-variable specific heat capacity of water. I'm
assuming that for a dual-load device, the flow rate and SHC are
automatically compensated so long as you wait for a steady-state
endpoint.? Mass-flow calorimeters are certainly a different
matter, there I'm sure the expansion and any temperature-related
effects on the SHC needs to be allowed for.
The heat exchanger in the HP424 design
coolant loop is a source of error that probably needs a DC-RF
changeover to calibrate it out, also as you suggest, the pump
might generate a little heat, although if the pump is gentle and
isolated from the motor, that wouldn't be a problem.
The idea of using two cylinder pumps
driven together seems a reasonable solution, and very easy to
calibrate for identical volume flows over timescales of a few
seconds.? I don't think spring/ball or flap valves would suffice
though, I rather imagine driven valves would be needed for
ultimate precision.? If the input flow is from a large reservoir
and the output goes to a separate tank, that would eliminate the
variance of temperature between the sensors and eliminate the heat
exchanger.? If the input reservoir was held at a constant
temperature and was insulated and well-stirred, that would be
another step towards making the system independent of external
influences.? You could even adjust the flow rate to keep the
output temperature within a narrow range so reducing the errors
from conductive heat loss through the insulation around the loads
and blocks. Taking it to the extreme, you could enclose the blocks
in a copper box and heat it to same temperature as the blocks, all
but eliminating conduction losses
I don't actually *need* a precision
power meter. This would be a project for the sheer joy of making a
precision instrument in my home lab and machine shop, and might
even get me a few views on the 'choob.
--
Neil
On 12/08/2022 19:37, Jeff Green wrote:
toggle quoted message
Show quoted text
An EE friend reminded me water expands
with heat and the watt meters used in TV stations have a chart
for calibration. If I'm understanding it right, because the
water is less dense with temperature rise, a correction factor
must be applied that takes in to account this factor.
?
The dummy load has a resistor with
multiple water channels and water is circulated by a pump.
?
This is a grossly wrong example, the
real world will be a lot less.
?
At 40F say it takes 100W to raise the
water to 45 degrees, but it will only take 95W to raise it to
50F, 90 to raise it to 55, 85W to raise it 60F.
?
The above example overstates the
effect by insane amounts to demonstrate. I was told the rate
of change is linear and about 2% for ever 10 degrees
Fahrenheit.
?
Somewhere there should be charts that
give the expansion per degree of temperature rise.
?
My EE friend suggest we check to see
if there is a member who worked in a TV broadcast facility for
clarification.
?
I remember physics practical labs
where we placed a 4 sided paddle in an insulated water bath
and measured the temperature rise caused by the rotating
paddles.
?
I wonder if the water bath in a TV
transmitter power meter would show a temperature rise from the
mechanical energy added by the pump.
|
Re: Flow calorimeter for RF/Microwave power measurement
toggle quoted message
Show quoted text
From: [email protected] < [email protected]>
On Behalf Of Neil Smith G4DBN via groups.io
Sent: Friday, August 12, 2022 11:22 AM
To: [email protected]
Subject: [Test Equipment Design & Construction] Flow calorimeter for RF/Microwave power measurement
?
Jeff's reference to the Oct '63 "Electronics World" article reminded me that I'm working on a project for my Youtube channel for a balanced flow calorimeter that can measure to 750 W at 2.5 GHz and 250 W to 3.5 GHz and potentially higher
with waveguide loads. I'll be using two identical thick film RF power resistors mounted to copper blocks with embedded fluid channels.? The plan is to make it self-calibrating as much as possible with a facility to swap DC and RF inputs. I may just use my
30 gallon transmitter watercooling tank as the source and sink. Even at a total of 1.5 kilowatts DC plus RF, it takes almost 7 minutes to raise the tank temperature by 1 C.? Keeping the total temperature rise to 5 C requires 5 litres per minute flow rate.
I'll use a 200 volt DC 4 amp variable power supply to provide the comparison power.
I considered using a positive-displacement tandem pump to give a consistent volume flow rate with both loads fed with identical temperature coolant.
As I'm not really looking for more than a few percent accuracy, it might even not require dual loads, but where's the fun in that. Having seen this:
I wonder if it's possible to build an instrument with good precision in the 1-100 watt range using very small thick-film loads?
I may use a non-aqueous coolant to avoid corrosion, and have a heat transfer coil immersed in the water tank.
Ideally I want the measurement to be independent of flow rate, fluid characteristics, power level and ambient temperature and just act as a self-balancing bridge with DC in one side and RF in the other, with volts/amps DC as the output
and a reasonable settling time of maybe 20 seconds at 750 W if I can get the thermal mass low enough.
Has anyone built such a device?? How about advice for making it as independent of physical variables as possible?? What I'd like is as pure an RF power to DC volts/amps converter as possible.
On 12/08/2022 17:05, Jeff Green wrote:
While for RF, the information on this site might be relevant.
?
|
Flow calorimeter for RF/Microwave power measurement
Jeff's reference to the Oct '63
"Electronics World" article reminded me that I'm working on a
project for my Youtube channel for a balanced flow calorimeter
that can measure to 750 W at 2.5 GHz and 250 W to 3.5 GHz and
potentially higher with waveguide loads. I'll be using two
identical thick film RF power resistors mounted to copper blocks
with embedded fluid channels.? The plan is to make it
self-calibrating as much as possible with a facility to swap DC
and RF inputs. I may just use my 30 gallon transmitter
watercooling tank as the source and sink. Even at a total of 1.5
kilowatts DC plus RF, it takes almost 7 minutes to raise the tank
temperature by 1 C.? Keeping the total temperature rise to 5 C
requires 5 litres per minute flow rate. I'll use a 200 volt DC 4
amp variable power supply to provide the comparison power.
I considered using a
positive-displacement tandem pump to give a consistent volume flow
rate with both loads fed with identical temperature coolant.
As I'm not really looking for more than
a few percent accuracy, it might even not require dual loads, but
where's the fun in that. Having seen this:
I wonder if
it's possible to build an instrument with good precision in the
1-100 watt range using very small thick-film loads?
I may use a non-aqueous coolant to
avoid corrosion, and have a heat transfer coil immersed in the
water tank.
Ideally I want the measurement to be
independent of flow rate, fluid characteristics, power level and
ambient temperature and just act as a self-balancing bridge with
DC in one side and RF in the other, with volts/amps DC as the
output and a reasonable settling time of maybe 20 seconds at 750 W
if I can get the thermal mass low enough.
Has anyone built such a device?? How
about advice for making it as independent of physical variables as
possible?? What I'd like is as pure an RF power to DC volts/amps
converter as possible.
--
Neil G4DBN
On 12/08/2022 17:05, Jeff Green wrote:
toggle quoted message
Show quoted text
While for RF, the information on this
site might be relevant.
?
|
Re: AC Voltage Calibrator, home built
I’ve an HP434A working perfectly. Its a great transfer standard
Ing. Patricio A. Greco
Taller Aeronáutico de Reparación 1B-349
Organización de Mantenimiento?Aeronáutico de la Defensa OMAD-001
Laboratorio de Calibración ISO 17025?AREA: RF/MW?
Gral. Martín Rodríguez 2159
San Miguel (1663)
Buenos Aires
T: +5411-4455-2557
F: +5411-4032-0072
toggle quoted message
Show quoted text
While for RF, the information on this site might be relevant. ?
|
Hi,
do NOT use JavaScript for something so complex.
WebAssembly allows you to use a real programming language. You
can, for example, use C# and the Uno Framework, and then get a
WebAssembly output web page which can run in ANY web browser, even
on Linux and Mac OS.
Tam
- - - - -
With best regards
Tam HANNA
Enjoy electronics? Join 13500 followers by visiting the Crazy Electronics Lab at
On 12.08.22 15:48, Dr. David Kirkby,
Kirkby Microwave Ltd wrote:
toggle quoted message
Show quoted text
Hi Dave:
One of the key things about the Kobe Instrument Division
(KID) is that they pay a lot of attention to the errors
surrounding the measurements their instruments make.? An
excellent reference is The Impedance Handbook.? There may
be a computer program (maybe an app) that will make those
calculations.
Hi,
The calculations to work out the uncertainty are in the
manuals for the 4284A and 4285A. The calculations are
non-trivial, and not easily put into a computer program, as
one needs to look at graphs. I did ask Keysight if there
were any spreadsheets or similar, but they said no.? I
suggested that they make one for their newer instruments -
they said they would consider that. But the fact is that
computing the uncertainty is not an easy task. I thought
about trying to create a web page to do it, which would
stretch my web skills to the limit. I don't know javascript,
and I suspect that's the best way.
--
Have Fun,
Brooke Clarke
Dave
|
Re: AC Voltage Calibrator, home built
On Mon, Aug 8, 2022 at 02:27 AM, tgerbic wrote:
I have lots of equipment to do what I would call hobby level (non-NIST) equipment calibration. Perhaps quite a few of us can say the same but I think the one area of weakness for most of us is a variable frequency, variable AC voltage source.
I think there are two issues with this. 1) Making the output stable enough. I have thought of the signal generator plus audio amplifier route myself, as someone else mentioned. I bought a Radio Shack (Tandy) amplifier for the purpose, but never actually got around to setting it up.? However, if the amplifier is run from the AC mains, I'd be quite surprised if there was not some influence on the output level with mains voltage. The internal regulators are only going to be so good, and I doubt they are good enough to calibrate a decent multimeter. 2) Assuming you get a stable waveform, calibrating it. I would have thought thermal methods with DC substitution about as accurate as you will get. My degree was? a "sandwich degree", where time is spent in industry. My 6-months was spent t the now demolished EQD Aquila calibration laboratories of the Ministry of Defense (MoD) in the UK. I know RF power measurements were based on? water. However, a Google would indicate NPL (UK) and PTB (Germany) are sampling with an ADC. If I were going to attempt AC voltage measurements, I would build something that relies on heating a resistor. This could be * Heat a resistor immersed in water, with a platinum resistance thermometer in there. Measure the temperature rise after t seconds. Repeat using DC. If the temerature rise is the same, then the RMS voltages were the same The absolute accuracy of the thermometer is not important - it just needs to be repeatable. This HP application note describes some RF power sensors. Unlike a commercial voltage or power meter, if you want a standard, you should not be too concerned how long it takes. I must admit, I am surprised that NPL and PTB are not using thermal methods. I did not read in full, but it looks as though NIST is so maybe my idea is not so bad as I started to fear. Dave Dave
|
Hi Dave:
One of the key things about the Kobe Instrument Division (KID) is
that they pay a lot of attention to the errors surrounding the
measurements their instruments make.? An excellent reference is The
Impedance Handbook.? There may be a computer program (maybe an app)
that will make those calculations.
Hi, The calculations to work out the uncertainty are in the manuals for the 4284A and 4285A. The calculations are non-trivial, and not easily put into a computer program, as one needs to look at graphs. I did ask Keysight if there were any spreadsheets or similar, but they said no.? I suggested that they make one for their newer instruments - they said they would consider that. But the fact is that computing the uncertainty is not an easy task. I thought about trying to create a web page to do it, which would stretch my web skills to the limit. I don't know javascript, and I suspect that's the best way.
--
Have Fun,
Brooke Clarke
Dave
|
Re: AC Voltage Calibrator, home built
On Mon, Aug 8, 2022 at 07:45 AM, Radu Bogdan Dicher wrote:
An obvious sample design to look at is?, at least to give some parameters to circumscribe what's done out there.?
I have not looked at the design close enough to figure?out how it's done, but it'd be interesting to unwrap?it.
Radu.?
I am suspicious of their claim of capacitors measured to 0.05%. My HP 4284A is replaced by the Keysight E4980A. Both those have a basic accuracy of 0.05%, but that worsens under every conceivable test condition. The process to work out the uncertainty is quite tiresome. So in essence, I don't think one can make cheap capacitor standards to 0.05%. Other than that, it looks interesting, but has very restricted ranges.
|
National Physical Laboratory (NPL) Good Practice Guides
Here's a lot of useful information about good practices for making measurements A list, at the time of writing the list is below. But I am aware of one other, on the characterisation of dielectric materials, which is not there. I have put that in the files section.
The complete list (no, it's not complete!)
|
Re: "Electric field strength" measurements?
A Standard Antenna is described by EIA/TIA-329-B.? I have built a few for UHF & microwave frequencies.
The standard gain is 7.7 dB.
|
Re: Making a Q-meter / References etc
On Thu, Aug 11, 2022 at 02:24 PM, Myosotis wrote:
Measurement using an oscilloscope or spectrum analyzer is often mentioned but it can be difficult to judge 3, 6 or 20 dB on either side of resonance.?
Back when I was measuring a lot of coil Qs using the 3db method and a scope, I figured out that 5 / 7 = 0.714, which is so close to 0.707, that on a scope you can't see the difference.
So, I would peak the signal at resonance, log the frequency, then use the variable knob (uncal) to set the waveform to 7 units, then move the oscillator frequency up until the scope read 5 units, log the frequency, then move the oscillator frequency down until the scope reads 5 units and log the frequency. The 0.714 vs 0.707 is a 3.5% error, however you are reading the upper 3db frequency lower than it actually is and you also reading the lower 3db frequency lower than it actually is (tiny amounts), so this almost cancels out, except for the geometric mean difference. Geometric mean - the 3db points don't have the exact same frequency difference from resonance, it is the geometric mean.
? Maybe someone smarter than I can figure out a correction factor, and tell me if it changes with Q. I suspect it does. and you would need a chart with a line showing Q vs Correction factor or vice versa. I would actually like to see that chart if anyone is interested in giving me enough info. I don't have much of a math background, so I will probably struggle with the info.
? I thought this site presented some useful info about measuring Q.
???????????????????????????????????? Mikek
|
Re: "Electric field strength" measurements?
Paul,
Good reason, I haven't tried it.
Ray, W4BYG
On 8/11/2022 12:34, Paul via groups.io
wrote:
That is why I
prefer to do my antenna work
after dark.
?
de Paul, W8AEF
?
?
Dave,
Thank you for your inputs.
I have a TinyVNA and I find the super small letters on
the 2.8" screen are
very difficult to read, when testing outside. Using it
or the PC computer
software inside works fine, but by itself outside, not
so much. If they ever
come out with a 4" version of the SA, maybe that would
suffice. They
certainly are in the right price range for HR and
hobbyist use.
I don't have the 4" TinyVNA so I don't yet know if that
is any better
outside.
Someone on the list may have one and be able to comment
on it.
Ray, W4BYG
On 8/10/2022 18:12, Dave W6OQ via groups.io
wrote:
Ray:
The TinySA spectrum analyzer may meet your needs.
Pocket portable, inexpensive,
covers HF thru UHF and beyond. Can detect unmodulated
signals. And the
linearity may be good enough that you won't have to
deal with calibrated
attenuators, though of course you can. There is a
group.io group at?/g/tinysa?that
is owned by the developer. Check in there for the
recommendations of where to
buy it so you get an original and not a worthless
clone.
Do you have any ideas for Standard antennas? I think
that there might be enough
info on the internet to build your own for some
frequencies. Never quite got
that far myself yet.
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
? Lebron and Heather Lackey
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
Lebron and Heather Lackey
|
Re: "Electric field strength" measurements?
Zvone,
Thank you for your thoughtfulness. I don't speak or read German, but
if the article is posted online, I can use Google to translate it.
Regards,
Ray, W4BYG
On 8/11/2022 12:03, zvonimirmavracic
via groups.io wrote:
Hello!
In July 2022 edition of German magazine Funk amateur, there is an
article on how to measure/calculate antenna gain
using? Two-antennas-method and VNA.
My knowledge on the subject is poor, so describing? the article
here? is not an good idea.?
But, if you want me to, I can scan the article and send it in
individual email.
Warning, as I said, article is in German.
73, Zvone, 9a5b
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
Lebron and Heather Lackey
|
Re: Making a Q-meter / References etc
Dear David,
Q measurement is a very interesting subject, especially to someone who competes in Top Band Direction Finding events.? The subject is glossed over in many modern textbooks but is covered in Foundations of Wireless and Radio and Laboratory Handbook, both by M G Scroggie B.Sc., M.I.E.E.
The Q Meter in theory and practice from Marconi Instruments contains excerpts from the manuals for the TF1245 and TF1246 and is essential reading for operators of similar instruments.
Interesting references are:
An overlooked Q meter is the Advance T1 & T2 series:
A design from Australia was featured in Electronics Australia June 1969.
A more recent design is a Novel Q Meter from EDN:
The Xtal Set Society has some fascinating articles on their site about Q but the links are not working this evening:
From memory some of their measurements were made using an HP 4342A which seems to be a rare instrument these days.
Many years ago I bought a TF 1245 and its companion oscillators TF 1246 and TF 1247; all three languished in storage until the start of the pandemic which gave me an opportunity to start overhauling them.? That was a long job, with the TF 1245 requiring a considerable amount of work including the rebuilding of a capacitor, replacement of a feed through capacitor (only a few left in stock at Farnell) and the rebuilding of the Q multiplier meter with parts obtained from a similar meter on EBay, the seller will be stunned if he ever finds out the proxy that I entered.
The TF 1246 tried to defy logical fault finding until I disconnected and measured all the resisters and then replaced them.
After that the two units were left on test 24 hours a day for 7 days before realignment, all of this took over a month.? A special jig was then made to test various antennas.
A problem with home constructed units is getting very low oscillator output impedance and a high Q variable capacitor.? The variable capacitor is, of course, in parallel with the inductor being measured, size and weight preclude the very high quality Marconi item from being transplanted into my Direction Finding receiver.
It would be possible to use high quality fixed capacitors and switch them into circuit via microprocessor control in a similar way to that used in automatic antenna matching / tuning units.
As I am sure you know Q (ul) is mainly theoretic, what matters are the loaded Q, Q(L) which will be changed by surrounding components and metal work.
Q of a varicap is usually given as about 200 and is a limiting factor in a DF receiver with 3 or 4 switches tuned frequencies.
Measurement using an oscilloscope or spectrum analyser is often mentioned but it can be difficult to judge 3, 6 or 20 dB on either side of resonance.? I have used an HP 3400A ac millivoltmeter and frequency counter with success.? Those instruments can be connected to the inductor via an FET source follower with several Megohms input impedance.? To avoid interaction with the coaxial connecting lead a differential amplifier can be used.
?
73, Geoffrey.
|
Re: "Electric field strength" measurements?
Dave,
Thank you for the inputs and interesting information.
In my past I organized and lead a field test of various
commercial and a home brew 40 meter ground mounted vertical
antennas. This was basically focused on the improvements
experienced when starting with no radials laid on the ground to
4 radials and then doubling each increment of that, up to 32
radials. The signal improvements with the
additional radials was like or better than, adding a KW
amplifier.
We built a full sized 40 meter ground plane for the
reference antenna. It was matched at the base for a 50Ω
impedance and fed with about 10 watts from a transceiver.
The match was optimized for each antenna tested.
Related to your comment about using fiber
between the sites: Fiber was not feasible at this time for us,
so in order to remove the affects of any cables out to the
receive site some 7 or 8 wavelengths away, W4TNS built a battery
powered 40 meter to 3/4 meter (no AGC) upconverter. We tested it
to find it's best operating input levels for best linearity and
made sure to operate the tests within those limits.
We utilized a small 40 meter receiving loop on 40 meters and a 5
element transmit yagi on 3/4 meters to feed the resulting
signals back to a Tektronix 2710 SA ,via another 3/4 meter yagi.
Both yagis were stably mounted at about 10'. The accuuracies
were subject to +/ - 1db amplitude variations in the SA, but the
preparation, process and the excercize, provided an awesome and
informative time for the 15 or 16 participants.
The tests
also revealed there was very little difference in signal
strength between the full size vertical and? the
commercial multi-band antennas on 40 meters, even though
the loaded antennas were usually shorter and more
complex than the full sized simple ground plane.
We did not have time to check the higher bands.
We did check several 40 meter mobile antennas and found
them to be somewhat directional depending on the
mounting locations, but surprisingly effective.
We realized the setup was
subject to several other variations, but we felt the tests would
still be helpful and useful. It was a fun ham radio activity to
be a part of. All that were there related they learned a lot.
73, Ray, W4BYG
On 8/11/2022 10:00, Dr. David Kirkby,
Kirkby Microwave Ltd wrote:
On Wed, 10 Aug 2022 at 21:15, Ray, W4BYG < w4byg@...>
wrote:
On
the thread "...Making a Q meter":
On 8/10/2022 15:42, Dr. David Kirkby, Kirkby Microwave Ltd
wrote:
> if you look at the description of the group
>
> /g/Test-Equipment-Design-Construction
In reviewing the listed subjects, I would like to query the
group on
relatively simple "Electric field strength" measurements.
If it can be measured it's on topic. I just
updated the list to exclude things like ghost detectors, but
otherwise, any measurement is on topic.?
Anyone have something to offer on the subject?
Ray, W4BYG
?
I did in a former job make field strength measurements
where the whole of a passenger plane was considered the
antenna - this was an expensive measurement to perform, as
the plane had to fly around a mountain for a few hours. We
used many tonnes of fuel as jet engines are inefficient at
low altitudes. ??????
Not wishing to discourage measurements, but the truth
is that modelling tools will be more accurate than
measurements in many cases.
Spectrum
analyzers are not particularly accurate measuring power.
If you look at the calibration instructions for a
professional spectrum analyzer, you will see that power
meters are used. A measuring receiver is a professional
tool for making power measurements at specific
frequencies. They are very expensive on the used market.
I have never looked, but I doubt that a spectrum
analyzer would be used when calibrating a measuring
receiver.?
A few random thoughts, on areas that others have not
discussed.
One of the things that has always concerned me about
antenna measurements is the influence of the cable and
support structure. This has got me wondering if the
detector should be a small battery powered device on the
antenna, which transmits the signal level by optical
fibre. The linearity of the detector is irrelevant, as
that can be measured separately on a bench. Optical fibre
is much lighter than any coax, so for small antennas,
which the mass of the antenna is a lot less than the coax,
this should allow smaller support structures.
A transmit antenna could have a small
battery powered oscillator.?
I recently set up two large metal plates and
applied AC from a signal generator to provide a known E
field from?
E = V / spacing
I only did this to prove a cheap Chinese
meter, which claimed to measure E and H from 20 Hz to 3.5
GHz was a piece of crap. I got a full refund via eBay, as
the seller would not pay the return carriage to China.?
?
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
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
Lebron and Heather Lackey
|
Re: "Electric field strength" measurements?
Geoffrey,
Thank you for the suggestions. I have downloaded the software and
will try it out. I appreciate your assistance. I will keep your
email on my desktop and be sure to ask, if I need further help.
73, Ray, W4BYG
On 8/11/2022 09:33, Myosotis via
groups.io wrote:
Dear Ray,
I would run some tests on your RSP Duo to check
it's accuracy and repeatability.? The Spectrum Analyser software
for it can be downloaded from:??
Using a low-cost SDR for logging
accurate RF power and SNR measurements can be found here:?
The SDR Console software has an on on
screen signal strength logging graph the data from which
can be exported to Excel etc.? The Air Spy software also
has a logging function.
I check the calibration of mine using a
-55 dBm output oscillator and check the settings for RF
and IF gain.? If have found it to be accurate and
repeatable.
There was an interesting page on the
SDRC website about the S meter readings but I cannot find
it, this is the nearest:
I use it for Medium Wave measurements, any
questions please ask.
Sorry about the bold sections, BOLD stopped working after I
copied the RS link.
73, Geoffrey.
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
Lebron and Heather Lackey
|
Re: "Electric field strength" measurements?
Everett,
Thank you. I have it.
Ray, W4BYG
On 8/10/2022 20:11, Everett N4CY via
groups.io wrote:
If you buy a SDRPlay, there is free SA software on SDRPlays
website.
Everett N4CY
On Aug 10, 2022, at 6:59 PM, Paul via
groups.io <w8aef@...> wrote:
?
Take a look
at the RTLSDR dongle.? Cheap
and lots of software available.
?
Paul, W8AEF
?
?
Harvey,
Thanks for your inputs. I have an RspDuo and an
Airspy+ . I've not tried them
for a application such as this. I tend to think
one would not be able to
resolve enough detail accuracy with an SDR, but
I have not tried it.
As for less costly commercial SA's, (all but the
TinySA ($100 or so, with
2.8" screen)), costs near $1,000, as best I can
see.? Also the specs
on what I have seen reveal questionable + and -
amplitude accuracy. Absolute
accuracy is not necessary to reveal any
differences between antenna signal
levels, but repeatability is important.
While I have much retirement time on my hands
and a some dollars to play with
for parts, the commercial alternative is still a
bit more than I want to spend.
I love building and experimenting.
Ray, W4BYG
On 8/10/2022 19:26, Harvey White
wrote:
If you
had a software defined Radio, could you dig
the data out of it?? No idea
about bandwidth or sensitivity, but it might
be sufficiently sensitive
depending on the frequency you're interested
in.? As an alternate thought,
aren't there some very inexpensive SA's out
there?? Would they be
sufficient?
Harvey
?
On 8/10/2022 6:46 PM, Ray, W4BYG
wrote:
Brooke,
Thank you for your comment. I agree using a
SA is probably the best way to measure
EMF's. Been there done that.
But it seems that with some of the new chips
today. a reasonable arbitrary log
characterization could be established (in
dbm or dbV) with a reference dipole
and then switch the feed to the antenna with
supposed gain (or loss) and use a
calibrated attenuator to match the level of
the reference antenna, then read
the delta between them on the attenuator as
gain or loss.
I suspect this has already been done by
those that are much smarter than I.
Just trying to find out if it's so...
Ray, W4BYG
On 8/10/2022 17:24, Brooke Clarke
via groups.io wrote:
Hi Ray:
I looked into Measuring EMFs and the best
result was based on using a spectrum
analyzer that has calibrated amplitudes
based on a 50 Ohm input.
?
?
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
Lebron and Heather Lackey
|
Re: "Electric field strength" measurements?
Harvey,
Thank you again. My earlier comments to you and then Dave, W6OQ
would seem to applicable as a response.
I appreciate your thoughtfulness.
73,
Ray, W4BYG
On 8/10/2022 19:26, Harvey White wrote:
If you had a software defined Radio, could you dig the data out
of it?? No idea about bandwidth or sensitivity, but it might be
sufficiently sensitive depending on the frequency you're
interested in.? As an alternate thought, aren't there some very
inexpensive SA's out there?? Would they be sufficient?
Harvey
On 8/10/2022 6:46 PM, Ray, W4BYG
wrote:
Brooke,
Thank you for your comment. I agree using a SA is probably
the best way to measure EMF's. Been there done that.
But it seems that with some of the new chips today. a
reasonable arbitrary log characterization could be
established (in dbm or dbV) with a reference dipole and then
switch the feed to
the antenna with supposed gain (or loss)
and use a calibrated attenuator to match the level of the
reference antenna, then read the delta between them on the
attenuator as gain or loss.
I suspect this has already been done by those that are much
smarter than I. Just trying to find out if it's so...
Ray, W4BYG
On 8/10/2022 17:24, Brooke Clarke
via groups.io wrote:
Hi
Ray:
I looked into Measuring EMFs and the best result was based on
using a spectrum analyzer that has calibrated amplitudes based
on a 50 Ohm input.
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
Lebron and Heather Lackey
--
"If you want to build a strong house, I'll give you my engineer's number.
If you want to build a strong life, I'll introduce you to my carpenter."
Lebron and Heather Lackey
|
Re: "Electric field strength" measurements?
That is why I prefer to do my antenna work
after dark.
?
de Paul, W8AEF
?
toggle quoted message
Show quoted text
From: [email protected]
[mailto:[email protected]]
On Behalf Of Ray, W4BYG
Sent: Thursday, August 11, 2022
9:26 AM
To: [email protected]
Subject: Re: [Test Equipment
Design & Construction] "Electric field strength" measurements?
?
Dave,
Thank you for your inputs.
I have a TinyVNA and I find the super small letters on the 2.8" screen are
very difficult to read, when testing outside. Using it or the PC computer
software inside works fine, but by itself outside, not so much. If they ever
come out with a 4" version of the SA, maybe that would suffice. They
certainly are in the right price range for HR and hobbyist use.
I don't have the 4" TinyVNA so I don't yet know if that is any better
outside.
Someone on the list may have one and be able to comment on it.
Ray, W4BYG
On 8/10/2022 18:12, Dave W6OQ via groups.io wrote:
Ray:
The TinySA spectrum analyzer may meet your needs. Pocket portable, inexpensive,
covers HF thru UHF and beyond. Can detect unmodulated signals. And the
linearity may be good enough that you won't have to deal with calibrated
attenuators, though of course you can. There is a group.io group at?/g/tinysa?that
is owned by the developer. Check in there for the recommendations of where to
buy it so you get an original and not a worthless clone.
Do you have any ideas for Standard antennas? I think that there might be enough
info on the internet to build your own for some frequencies. Never quite got
that far myself yet.
-- "If you want to build a strong house, I'll give you my engineer's number. If you want to build a strong life, I'll introduce you to my carpenter." ? Lebron and Heather Lackey
|
Dr. David Kirkby, Kirkby Microwave Ltd
Patricio A. Greco
Ray, W4BYG