On Fri, 2 Sept 2022 at 14:23, Tom, wb6b < wb6b@...> wrote: On Fri, Sep 2, 2022 at 05:29 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
I hope not! RMS power is a useless parameter . You can compute it analytically, but it is pretty meaningless. The mean power is what is relevant, as that causes the same heating as DC would.?
I think the measured amperage would be RMS, by virtue of measuring the temperature of the resistor. Guided by the title of thread, was only referring to current.?
Yes, that was my mis-understanding of what was written. Sorry.?
Interesting calculator for temperature to peak wavelength. I've had some trying out some common temperature values. The sample curves in the description are nice for getting a feel for how far the hot body spectrum would extend into the near infrared.?
? Yes. I should probably plot that on a log scale to get a better idea of how little/radiation is at 900 nm.
? The more I think about it, the more I think it is not going to work too well without heating the nichrome wire more than I really want to. Anyway, I should find out in a few days. I will probably play around with it towards the latter part of next week.
Tom, wb6b
|
Re: Cal Lab Magazine - International Journal of Metrology
Thank you very much, George. Thanks to you, I now have the 1927
edition of the Admiralty Handbook (archive.org has it, as well as
volume 1 of the 1938 edition).
And thanks to this thread, I have learned that the jar, as a unit of
capacitance, is 10/9 nF. Apparently, it was mainly used by the Royal
Navy. I wonder what the prototype jar was (Leyden? Marmite?)
--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/2/2022 05:20, Labguy wrote:
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Show quoted text
I happen to have a 1931 copy of The
Admiralty Handbook of Wireless Telegraphy, a great tome for
its day. It speaks of capacitance in jars.
?
I also have a 1927 copy of "Les Ondes
Electriques Courtes" (Short Electric Waves). I picked this up
at a university book fair for $0.50 some years ago. Makes for
great reading to see how things were done in those days.
?
I had a look to see if it contained
anything about units for capacitance. It shows circuits for
transmitters, but all have the transmit signal that is used to
drive output triodes derived from mechanical generators. The
output stage shows a capacitor in the tank circuit, but
unfortunately no units.
?
Cheers,
George
VK2KGG
?
?
?
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On
Behalf Of Tom Lee
Sent: Thursday, 1 September 2022 7:16 PM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Cal
Lab Magazine - International Journal of Metrology
?
I just took a look at a few hobbyist
magazines and some product
schematics from several different
decades, and your speculation looks
pretty solid. Based on that random,
statistically insignifcant sample,
the UK has been quite consistent over
time and across publications aimed
at quite different readers. The US, not
so much, even within a single
company. The earliest schematic for HP's
first product, the 200A,
surprised me with its use of the mu
symbol. A schematic for the same
product, but of later manufacture, uses
"m" for micro. a seemingly
backwards step. Textbooks and refereed
journals paid the extra ha'penny
for a mu, but hobby magazines were a
different story.
?
I did not check any German or French
pubs to see what conventions were
followed there.
?
-- Cheers,
Tom
?
|
I think the basic RF connection would be very simple. I often make fairly well matched 50 ohm loads by connecting 2 100 ohm chip resistors from a BNC center pin to ground connections (radial and spaced 180 degrees on either side). The interesting part depends upon how one plans the readout and the thermal design [both should be allowed to heat up significantly (for sensitivity) and equally (for accuracy)]. The readout will probably require a capacitor and, possibly, and inducttor for RF/DC isolation in proximity to the RTD sensors.
|
On 9/2/22 07:34, SCMenasian wrote: I'd like to suggest another option. I have some Platinum RTD temperature sensors bought for another project. They are very stable and accurate as temperature sensors and relatively cheap. They are also very small - small enough to be used as an RF load in a BNC or SMA fixture, with bandwidth extending, possibly, to the low GHz region. Mine have leads; but they are available in surface mount packages. 100 Ohms is the most commonly supplied resistance; so 2 in parallel could make a nice 50 Ohm load.? A third sensor could serve as a reference in a bridge circuit. Alteratively, one might preheat to a known temperature with DC and measure the DC power drop required to achieve the same temperature with RF applied. Other readout options also exist, including lock-in if the RF power can be modulated. That sounds good. How would you do the RF load connection to coax to not have reflections? What is the "mount package" like? Solves the connection to coax problem?
|
The page posted by BH1BPG may be of interest. Limited frequency
range but useful for many.
https://sites.google.com/site/linuxdigitallab/rf-homebrew-instrument/thermistor-rf-power-meter
|
Re: DC-5.5 GHz signal generator evaluation boad
Mike,
The HP 8640B was a very nice sig gen in its day, but it's older than
half the people on the planet. The high end of the HP 8640B is about
1000 MHz with the extended frequency option, so it's unlikely you can
find any specs at the top of its range. I have two 8640Bs. One has
the extended range and the other doesn't, but curiously, BOTH show
that they go to 1000MHz ... but one has zero output above the stock
freq range of about 500 MHz, even though it indicates the higher
frequency. I don't know if it was tampered with, or if this was a
"feature" from the factory.
Also, I mis-spoke earlier -- the AD eval board under discussion uses a
RasPi 3B and not a 4, so I'll have to find one of those, probably in
Lower Elbonia.
73
Jim N6OTQ
|
Re: DC-5.5 GHz signal generator evaluation boad
Jim, your mention of the HP 8640B made
me curious about the SSB phase noise
specs of the AD9166 system.? At 100 MHz
it appears to be equivalent to that of
the 8640B, but I couldn't find a spec
for the 8640B at 1000 MHz to compare
the two signal generators.? I agree that
the price of the AD9166 and frequency
coverage makes it an attractive alternative,
especially if low SSB phase noise is required
to serve as a reference source.
Mike, K8CN
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CAUTION: This email originated from outside of the University System. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Hmm, one issue with the eval board is -- the dox for the eval board
show it being used with a Raspberry Pi 4 board, which is nearly as
much unobtainium as the USD$599 that the eval board costs, and right
now on the scalper's market, nearly as expensive too.
Still, it's a rather attractive bit of kit, and if I ever get my RasPi
4 from my globe-trotting brother, I might look at getting an eval
board.? For the price and the frequency span, it beats my old HP8640B
freq generator 10 ways from Sunday.
My birthday is next week, and Christmas is just around the corner.? So
maybe I know what I'm going to give myself.
73
Jim N6OTQ
On Fri, Sep 2, 2022 at 6:29 AM Neil Smith G4DBN <neil@...> wrote:
>
> I had a look at the AD9166 when it was released, but the price for just
> the chip was off-putting. Current 10-off cost from Mouser UK just for
> the 9166 chip seems to be ?639 + tax.
>
>
> Also the package being a 324 pin BGA makes it a bit tricky for home
> construction.
>
> If they are offering the populated eval board at $599 with all of the
> supporting components as well, then it's an absolute bargain, although i
> think I'd just invest that much cash in another old HP4433.
>
> Neil
>
> On 02/09/2022 12:12, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
> > This not exactly pocket money at $599
> >
> >
> >
> > But the evaluation board could form the basis of a low cost signal
> > generator or other bit of RF test kit.
|
The advantage of the chip resistor would be frequency range and true RMS readings.
?
I hope not! RMS power is a useless parameter . You can compute it analytically, but it is pretty meaningless. The mean power is what is relevant, as that causes the same heating as DC would.?
I'm a bit confused. He said RMS, not RMS power. Isn't "RMS power" a meaningless term? Voltage and current can be RMS, and the end result is precisely what you say, the same heating (work) as DC would do.
The discussion was about RF current, so I assumed "RMS" meant "RMS current", in this context.
Steve Greenfield AE7HD
|
I'd like to suggest another option. I have some Platinum RTD temperature sensors bought for another project. They are very stable and accurate as temperature sensors and relatively cheap. They are also very small - small enough to be used as an RF load in a BNC or SMA fixture, with bandwidth extending, possibly, to the low GHz region. Mine have leads; but they are available in surface mount packages. 100 Ohms is the most commonly supplied resistance; so 2 in parallel could make a nice 50 Ohm load.? A third sensor could serve as a reference in a bridge circuit. Alteratively, one might preheat to a known temperature with DC and measure the DC power drop required to achieve the same temperature with RF applied. Other readout options also exist, including lock-in if the RF power can be modulated.
Stephen Menasian
Stephen Menasian
|
Those bolometer chips work from well
below zero (C or F) to a few hundred. Getting the environment for
the sensing element to be consistent and stable over the
measurement period is always going to be a challenge, but if you
run DC and RF at the same time and run with the sensor at a
constant temperature in a temperature-controlled housing, it ought
to be possible to remove environmental influences simply by
servoing the DC with a PID loop to keep the temperature of the
element constant.? Ideally it would be in a vacuum so the only
heat loss was via radiation into an environment which acts as a
black body at a fixed (lower) temperature, and by conduction
through the mount and connections, but a sealed enclosure with air
would probably be OK given the enclosure is at a fixed temp and
the servo drives the sensor to the same fixed temp. It's
self-calibrating as well of course, only requiring precise
measurement of the DC current and compensation for frequency
response.
Using a contact thermistor would reduce
the sensitivity by increasing the thermal mass of the sensor, but
perhaps not by more than half.? Usually you have to compensate for
the heating effect of sensing current in the thermistor, but if
the sensor is held at a constant temperature, heating from the
sensing current of the thermistor would be constant once the loop
settled.? Also the thermistor could be sampled with a very low
duty cycle A/D converter to reduce the heating to imperceptible
levels.? Two 0402 SMD chips with short foil connections and
thermal glue in a cutout on a PCB and enclosed in a black-painted
milled aluminium enclosure with a mosfet heater and temp control
chip perhaps?
DC injection would need an isolated
supply and wideband conical chokes.? Hmmmm. Sounds like a whole
lot of fun.?
Neil
On 02/09/2022 13:29, Dr. David Kirkby,
Kirkby Microwave Ltd wrote:
toggle quoted message
Show quoted text
On Fri, 2 Sep 2022 at 03:08, Tom, wb6b < wb6b@...>
wrote:
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.?
I am personally interested in doing this in a
low impedance circuit. That probably means having a
transformer with a single turn on the secondary. A bit of
nichrome wire as the secondary would be convenient if it could
be the current sense too.
The advantage of the chip resistor would be frequency range
and true RMS readings.
I hope not! RMS power is a useless parameter .
You can compute it analytically, but it is pretty meaningless.
The mean power is what is relevant, as that causes the same
heating as DC would.?
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.
Yes, that does seem to be the case. The peak of
the emission curve
Assuming this calculator is right?
the peak emission vs temperature are
20 ¡ãC ?= 9.885 um
100 ¡ãC = 7.766 um
500 ¡ãC = 3.748 um
1000 ¡ãC = ?2.276 um
2447 ¡ãC = 900 nm (peak sensitivity of IR LED
I ordered)
It¡¯s clear that a black body resistor or
nichrome wire would not have its peak radiation anywhere
near the peak sensitivity of the silicon photodiode, but
it might be usable. For a ?1 each, with free next-day
shipping, it is worth a try.
Tom, wb6b
Dave
_._,_._,_
|
On Fri, Sep 2, 2022 at 05:29 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
I hope not! RMS power is a useless parameter . You can compute it analytically, but it is pretty meaningless. The mean power is what is relevant, as that causes the same heating as DC would.?
I think the measured amperage would be RMS, by virtue of measuring the temperature of the resistor. Guided by the title of thread, was only referring to current.? Interesting calculator for temperature to peak wavelength. I've had some trying out some common temperature values. The sample curves in the description are nice for getting a feel for how far the hot body spectrum would extend into the near infrared.? Tom, wb6b
|
One technique , I think it was an HP RF power meter. Used a thermistor in a bridge configuration, which had a bias supply to set the thermistor to a particular resistance. When the RF was applied, it unbalanced the bridge. The bias, was (automatically) controlled, and reduced until the bridge was in balance. And this control loop indicated the applied RF power. ? Rodger Bean ?
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Show quoted text
From: [email protected] <[email protected]> On Behalf Of Tom, wb6b
Sent: Friday, 2 September 2022 21:45
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] RF Current meters? On Fri, Sep 2, 2022 at 03:34 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote: I use nichrome wire to cut foam inserts for VNA calibration kits my company sells. I use a fairly thick wire, and put 5.5 A in it, so it glows red hot. But I will be able to put the photodiode near that and see at what current I can detect it. I would hope the IR could be detected long before I can see the wire getting hot, but maybe not. At least it costs virtually nothing to try. I have a high-resistance meter which will read pA (maybe even fA), so knocking something up quick should be easy.
This will be very interesting to find out at what point the temperature of the wire gets to the point that it can be detected by a near infrared diode. Definitely has a possibility of being good low cost method. While I was thinking about light bulbs because the filament may be thermally isolated inside the bulb, the possible inductance issue is well taken. Plus nichrome wire, if ?remember correctly, has a fairly low change in resistance with temperature, unlike the light bulb.?
Will be interested in watching for your results. And if the temperature that the nichrome wire may need to operate at is fairly high, this may lessen the need to compensate for ambient temperature.
Tom, wb6b
|
On Fri, 2 Sep 2022 at 03:08, Tom, wb6b < wb6b@...> wrote: 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.? I am personally interested in doing this in a low impedance circuit. That probably means having a transformer with a single turn on the secondary. A bit of nichrome wire as the secondary would be convenient if it could be the current sense too.
The advantage of the chip resistor would be frequency range and true RMS readings.
I hope not! RMS power is a useless parameter . You can compute it analytically, but it is pretty meaningless. The mean power is what is relevant, as that causes the same heating as DC would.?
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.
Yes, that does seem to be the case. The peak of the emission curve
Assuming this calculator is right?
the peak emission vs temperature are
20 ¡ãC ?= 9.885 um 100 ¡ãC = 7.766 um 500 ¡ãC = 3.748 um 1000 ¡ãC = ?2.276 um 2447 ¡ãC = 900 nm (peak sensitivity of IR LED I ordered)
It¡¯s clear that a black body resistor or nichrome wire would not have its peak radiation anywhere near the peak sensitivity of the silicon photodiode, but it might be usable. For a ?1 each, with free next-day shipping, it is worth a try.
Tom, wb6b
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
|
Re: Cal Lab Magazine - International Journal of Metrology
I happen to have a 1931 copy of The Admiralty Handbook of Wireless Telegraphy, a great tome for its day. It speaks of capacitance in jars. ? I also have a 1927 copy of "Les Ondes Electriques Courtes" (Short Electric Waves). I picked this up at a university book fair for $0.50 some years ago. Makes for great reading to see how things were done in those days. ? I had a look to see if it contained anything about units for capacitance. It shows circuits for transmitters, but all have the transmit signal that is used to drive output triodes derived from mechanical generators. The output stage shows a capacitor in the tank circuit, but unfortunately no units. ? Cheers, George VK2KGG ? ? ?
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Show quoted text
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Tom Lee
Sent: Thursday, 1 September 2022 7:16 PM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Cal Lab Magazine - International Journal of Metrology ? I just took a look at a few hobbyist magazines and some product schematics from several different decades, and your speculation looks pretty solid. Based on that random, statistically insignifcant sample, the UK has been quite consistent over time and across publications aimed at quite different readers. The US, not so much, even within a single company. The earliest schematic for HP's first product, the 200A, surprised me with its use of the mu symbol. A schematic for the same product, but of later manufacture, uses "m" for micro. a seemingly backwards step. Textbooks and refereed journals paid the extra ha'penny for a mu, but hobby magazines were a different story. ? I did not check any German or French pubs to see what conventions were followed there. ? -- Cheers, Tom ?
|
Re: DC-5.5 GHz signal generator evaluation boad
Hmm, one issue with the eval board is -- the dox for the eval board
show it being used with a Raspberry Pi 4 board, which is nearly as
much unobtainium as the USD$599 that the eval board costs, and right
now on the scalper's market, nearly as expensive too.
Still, it's a rather attractive bit of kit, and if I ever get my RasPi
4 from my globe-trotting brother, I might look at getting an eval
board. For the price and the frequency span, it beats my old HP8640B
freq generator 10 ways from Sunday.
My birthday is next week, and Christmas is just around the corner. So
maybe I know what I'm going to give myself.
73
Jim N6OTQ
toggle quoted message
Show quoted text
On Fri, Sep 2, 2022 at 6:29 AM Neil Smith G4DBN <neil@...> wrote:
I had a look at the AD9166 when it was released, but the price for just
the chip was off-putting. Current 10-off cost from Mouser UK just for
the 9166 chip seems to be ?639 + tax.
Also the package being a 324 pin BGA makes it a bit tricky for home
construction.
If they are offering the populated eval board at $599 with all of the
supporting components as well, then it's an absolute bargain, although i
think I'd just invest that much cash in another old HP4433.
Neil
On 02/09/2022 12:12, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
This not exactly pocket money at $599
But the evaluation board could form the basis of a low cost signal
generator or other bit of RF test kit.
|
On Fri, Sep 2, 2022 at 03:34 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
I use nichrome wire to cut foam inserts for VNA calibration kits my company sells. I use a fairly thick wire, and put 5.5 A in it, so it glows red hot. But I will be able to put the photodiode near that and see at what current I can detect it. I would hope the IR could be detected long before I can see the wire getting hot, but maybe not. At least it costs virtually nothing to try. I have a high-resistance meter which will read pA (maybe even fA), so knocking something up quick should be easy.
This will be very interesting to find out at what point the temperature of the wire gets to the point that it can be detected by a near infrared diode. Definitely has a possibility of being good low cost method. While I was thinking about light bulbs because the filament may be thermally isolated inside the bulb, the possible inductance issue is well taken. Plus nichrome wire, if ?remember correctly, has a fairly low change in resistance with temperature, unlike the light bulb.? Will be interested in watching for your results. And if the temperature that the nichrome wire may need to operate at is fairly high, this may lessen the need to compensate for ambient temperature. Tom, wb6b
|
Re: DC-5.5 GHz signal generator evaluation boad
I had a look at the AD9166 when it was released, but the price for just the chip was off-putting. Current 10-off cost from Mouser UK just for the 9166 chip seems to be ?639 + tax.
Also the package being a 324 pin BGA makes it a bit tricky for home construction.
If they are offering the populated eval board at $599 with all of the supporting components as well, then it's an absolute bargain, although i think I'd just invest that much cash in another old HP4433.
Neil
toggle quoted message
Show quoted text
On 02/09/2022 12:12, Dr. David Kirkby, Kirkby Microwave Ltd wrote: This not exactly pocket money at $599
But the evaluation board could form the basis of a low cost signal generator or other bit of RF test kit.
|
DC-5.5 GHz signal generator evaluation boad
This not exactly pocket money at $599
But the evaluation board could form the basis of a low cost signal generator or other bit of RF test kit. ? -- 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
|
On Fri, 2 Sept 2022 at 03:46, Tom, wb6b < wb6b@...> wrote: 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
I would not expect it to be necessary for the bult to be visible to the human eye before an IR photodiode could detect it. But I don't know. The issue I see with bulbs is their inductance. The other thing is I want to use a step-down transformer to drive the resistor. That probably means having one turn on the secondary. That one-turn could be a piece of nichrome. It is available as a strip, which would reduce the inductance compare to a cylindrical wire.
I use nichrome wire to cut foam inserts for VNA calibration kits my company sells. I use a fairly thick wire, and put 5.5 A in it, so it glows red hot. But I will be able to put the photodiode near that and see at what current I can detect it. I would hope the IR could be detected long before I can see the wire getting hot, but maybe not. At least it costs virtually nothing to try. I have a high-resistance meter which will read pA (maybe even fA), so knocking something up quick should be easy.
|
Hello,
?
I recently built such a LISN unit.
?
You can find a brief description here:
?
?
Sorry, it is presently only available in German but I guess the online translation tools should help.
?
Kind regards
?
Matthias
?
?
?
?
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
|
Dr. David Kirkby, Kirkby Microwave Ltd