EEVblog

How to make your own magnetic H-field EMC probe out of semi-rigid coax for $10 that performs identically to a $300 commercial probe!
Search for "Low noise amplifier" and "semi-rigid rg402" on ebay.
Forum: www.eevblog.com...
Bitcoin Donations: 38y7DE8HEHNj8fGDtUr4PkCn9nWxiorvvy
Litecoin: ML7oQokTwB38bgzzjLDbRV97HKAHuwRfHA
Ethereum: 0x11AceA38DCA9DbFfB4F35f3F746af65F9dED28ce
EEVblog Main Web Site: www.eevblog.com
The 2nd EEVblog Channel: / eevblog2
Support the EEVblog through Patreon!
/ eevblog
AliExpress Affiliate: s.click.aliexpr...
Buy anything through that link and Dave gets a commission at no cost to you.
Stuff I recommend:
kit.com/EEVblog/
Donate With Bitcoin & Other Crypto Currencies!
www.eevblog.co...
T-Shirts: teespring.com/s...
Likecoin - Coins for Likes: likecoin.pro/@...

[@patryksikora5262]

I'm looking forward to next video "Build a $100 DIY Spectrum Analyzer"

[@TheBananaPlug]

It might not be $10, but the W7ZOI homebrew SA was a good design/project from the '90's, rebooted here: hfsignals.blogspot.com/p/specan-reboot-of-w7zoi.html

[@pa4tim]

I have done that (500 MHz) , is a lot of work, by the time it was finished I had a few real SA's. www.pa4tim.nl/?p=1643 , it is a while back so the page is in Dutch, newer projects etc are in English.

[@daskasspatzle2396]

Now build a additional spectrum analyzer for 10 bucks and every one is happy ;-)

[@redsquirrelftw]

Would a SDR make a decent spectrum analyzer? I guess most have a more limited range though.

[@JohnDoe-hm8lr]

It would definitely work, although you'd have to be careful about the input signal level as they saturate easily, it also takes a good amount of time to sweep a large bandwidth.

[@soothcoder]

Yes a HackRF would have more than enough frequency range although slow sweep (but then do we care?). They are a bit 'deaf' though. Can't hurt to try though can it?

[@PlaceholderforBjorn]

Test it with RTLSDR for 10$

[@amaldev000]

Dave should probably do a video with $165 handheld spectrum Analysers from rfexplorer.com

[@acetyra]

Need more of these typ of videos

[@streaky81]

I got loads of those RF amps sitting around, they're handy because you can use a buck converter and set the output voltage to calibrate gain with them, no need to use an attenuator.

[@hgbugalou]

That coax looks like they just dipped normal braided shielding and dipped it in some solder.

[@Master_zzz]

That is exactly what they did.

[@StreuB1]

Thats how many places make semi-rigid in the smaller coax styles. Very common.

[@notamouse5630]

You don't need plasti-dip for probe coating, use electrical tape. It almost looks like the cheaper one could be prototyped in strip board if the need was urgent enough. For a cheap spectrum analyzer, attach a 10 MSPS SPI ADC to a raspberry pi, write some code to perform FFT on the data using the GPU and pipe the output to a graphing utility to get an approximation of a spectrum analyzer.

[@seanet1310]

Good noise floor for the couple dollar pre-amp. I've seen worse from decent commercial jobs. You can also make a quick and dirty e-field probe by cutting away some shield leaving a very short stub of the solid core conductor then insulating against shorts. Even if you don't have a specan these tools are useful with an oscilloscope (you will need the preamp). If it has fft like most dso do then that is a bonus. Home made H-felds are great, beat the old emco kit any day of the week

[@commonmogoreanu7135]

That's the kinds of videos we are here for. Thank you!

[@NetworkXIII]

Great video as always, Dave. We’re dealing with an EMC issue on a project right now..

[@VincentFischer]

I love RG402. Nothing better for DIY antennas

[@pawematuszczak7316]

Great video! Waiting for Part 2 with a little EMI pre-testing howto!

[@Mustakari]

Excellent! Thank you Dave. Videos like this are why I subscribe to EEVblog.

[@eglkFlyer]

Love the enthusiasm. How about doing the E field probe next ?

[@SomeMorganSomewhere]

Cat nail scissors are excellent for stripping braid off small coaxes.

[@parpid]

Frigging amazing hack! Everyone is going to build one. Thank you Dave, really

[@TheNoBSZone]

Great video. In the pre-compliance process right now for an IVD device with the cheapest company on the planet.. I seriously hope it doesn't come down to me building one of these. Thanks.

[@nathanielreid4967]

A good appropriate spray paint should do the same job nicely as the plastic dip here.

[@manickn6819]

Excellent video. This was quite interesting and useful. Please do the video in compliance.

[@w5cdt]

I built one too. Works fine!

[@Hackinside]

I love this kind of videos comparations. More videos like that, please. Expensive VS Cheap. Who is gonna win?

[@EEVblog]

Usually there is a performance difference, but in this case pretty identical!

[@Hackinside]

@@EEVblog ​ EEVblog I agree. But for a simple mortal like me and others learners, $10 to $300 makes a lot of difference.

[@evic262]

39 dislikes are from EMC probe manufacturers lol

[@Tortillin0077]

For an electronics engineer doing mainly pcb design for digital high speed or RF applications, how important/relevant is having a professional engineer's licence in getting a job in this field? I ask for those that practice engineering in countries where the profession is broadly regulated.

[@khemrajramsamooj9334]

@EEVblog can you do a tutorial with using an SDR and an EMC probe?

[@f.hababorbitz]

I NEVER found using this type of probe to find where the RE noise was coming from. The noise was everywhere, every component, every power rail. So trying to fix an RE compliance issue was not done with this sort of test gear. We joked that what we needed was eye sight that could see the circuit board in the frequency of interest to find the component and power connections radiating. What I did learn was how to design proper decoupling to each component, and paying special attention to components that drove wide processor bus (octal, 16) paths, as these are charging the circuit traces which is what causes the RE problem in the first place. Our PC design department was useless, as they would just place the decoupling components around the board. We figured out how to source the power for each IC on the PWB, so they were not directly connected to the power planes, but instead to multiple capacitors, which then had power connected to Vcc and such. The inductance of these traces had to be kept minimal. The idea is that the decoupling provided the high frequency currents for charging the board capacitance/inductance. It was tough, as we dealt with non technical board designers, that wanted to turn the autorouter on.

[@milantrcka121]

It takes a smaller loop - which will provide higher spatial resolution. 2 turns of 32awg (or so) enameled wire on 2-3mm dia (wire wrap wire also works), 50-ohm resistor in series and coax. Preamp required. Works well.

[@f.hababorbitz]

@@milantrcka121 I never found any ability to find the source of the emission as any quantitative measurements were "noise here, and more noise there". The circuit boards were 150mm X 250mm. In 1988 the processor frequencies were 6-10MHz, but this morphed to 32MHz, to 128Mhz. The lab had multiple HP brand probes. When I was still green starting out, the technicians just laughed, as they knew the root cause of the emission was not found by this method. The RE plot would show which processor frequencies were the source of emission limit exceeded. So we would try to bandaid the boards with capacitors and such. In the end, these original designs were ultra crap, and the fix was a new board layout. My job was to integrate a card cage of 19 microprocessors and make it pass the environmental requirements. This was avionics, the test methods were from RTCA DO-160 (version G when I retired). There were very deep notches to the RE bode plot at the comm radios, and nav radio frequencies. And super position of the emissions from these processors was a challenge.

[@milantrcka121]

Well if the emissions are everywhere, then the design has a major problem as described. Been there, fixed that.

[@codebeat4192]

Excellent video, more diy stuff. The difference in price is shocking, electrons spontaneously felt off if they had any notice of value.

[@vincei4252]

Oh, nice. I saw the other EMC video and was thinking about 3d printing something and winding the head with the various reels of magnet wire I have here. I also have lots of rigid coax so winner, winner chicken dinner.

[@neuralnetwork653]

Fascinating! Thank you!

[@mohammadsarmadi8884]

thank you for your good videos, in some resources has been mentioned that hand made H probes should terminated by 50 ohm resistor. what is your opinion?

[@dieboodskapper]

BOBBY DAZZLER!!!!! NOW I JUST NEED A SPECTRUM ANALIZER..$2000...DOWE!!!!

[@thatredkite8310]

Now i want a spectrum analyzer

[@Ezzell_]

Besides seeing the emf radiation...what other issue can be troubleshot with these probes?

[@jeanpierredaviau7478]

Does he solder the inner wire to the inner wire?

[@heyikidebir]

How it compares to an oscilloscope probe with it's ground clip connected to tip, forming a loop?

[@testits2295]

do i need to connect the core to the GND? Thanks

[@beachboardfan9544]

I know the acronym emi and emc, but what is H field's meaning?

[@ManicMender]

@EEVblog, would a probe like this work on picking up the signal on an automotive ignition coil, like the coil on plug units. I have seen pickups made for such, but if I can make my own, that would be awesome.

[@ebb2421]

the RG402 is available with an insulated jacket, then you just dip the loop.....

[@EEVblog]

Ah, interesting, they didn't show up in my ebay search.

[@shakaibsafvi97]

What's in the V-Field Probe ? Open ended conductor ?

[@EEVblog]

Yup!

[@shakaibsafvi97]

@@EEVblog thanks.. I'll try that too ! I'll be designing it in Altium. Multilayer PCB with amp built-in with battery.

[@borayurt66]

Building the probe is very easy, having a spectrum analyzer around is not.

[@MohamedAfzal]

what is the use of those probes?

[@FalcoGer]

Holy shit. How can they get away with selling a 300 buck kit that has like $5 worth of parts in it?

[@darknessblades]

just a question but do you know how i can make a 94V DC small and simple power supply to use on old led strips from a broken TV since i cant find any scematic online for a 94V version only 5-12-24-36V

[@km5405]

dave don't ruin your snips you maniac. ... also, maybe the temperature drift is bigger?

[@nipunagunarathne4882]

*dreams of slapping a 9V PP3 on it- dashed *

[@andreicharpentierquesada4530]

OMG ARE SO SIMILAR, I HAVE TO MAKE ONE

[@brothertheo2677]

Its not rigid, its semi-rigid coax

[@tablatronix]

One of the best videos in a while!

[@RicoElectrico]

@qashqai q Spot on. I'd rather have Dave post rarer, but higher effort content. I don't watch the mailbags anymore, they seem to become a chore for him. Teardowns are a hit or miss really. Dave sometimes does too little research. Though that correlates with "off-the-cuff" slogan.

[@EEVblog]

RicoElectrico Correct, I do practically zero research, that's the way I've always done videos and have built my channel from nothing doing that.

[@urdnal]

@@EEVblog How about more DIY expensive tools that work as well as the professional ones. Stickin' it to the man. How about an active oscilloscope probe next? Or a DIY Hewlett Packard 547a current tracer? I could probably use one but not enough to justify $200 on ebay

[@midnightman011]

Totally agree .. high quality content .. stick it to the fat cats Dave .. maybe build a differential probe next from Ebay parts .. there are a ton of broke engineers and hobbyists out there

[@jafinch78]

Yes sir. An RF probe came to mind from an old set of computer external speakers... that'd be about as cost effective. SDR ideas don't seem bad for cheap spectrum analyzers especially if there is an oscilloscope plugin... though I've figured a set of attenuators for the range and profiling the SDR well to know its range of performance to characterize the limitations so you don't blow it up. Probably a current limiting input thingamajiggy too. Normalizer dohicky would be impressive. Least that's what comes to mind. I was also wondering about making a leveling head for the cheapo signal generators since they're so cost effective. Trips me out how cheap some of the modules are and how like this detailed video demonstrates using the hardline or rigid or I guess it's called semi-rigid cable... can be used to make decent kit alone basically or with a or some modules. So much, I just ordered a range of modules, plus some, to make an Antenna Analyzer or looks like is going to be a VNA using Erik's latest modularized version he notes on the SoftwareControlledHamRadio groups.io post on Analyzer Comparison since seems impressive: github.com/erikkaashoek/Tapr-VNA

[@RemcoStoutjesdijk]

You had time to build it to scale and to paint it!!!

[@EEVblog]

Only two coats!

[@altersami9660]

@@EEVblog I believe this would do a better job coating it than the spray-can version: www.amazon.com/Performix-11602-6-075815116024-Plasti-Dip/dp/B000ZN1T16/ref=sr_1_9?keywords=plastidip&qid=1549645102&sr=8-9

[@DavidLindes]

@@altersami9660 yeah... I saw the name Plasti-DIP ... and a spray can, and I was like... what? Plasti-Dip is supposed to be a thing you *_DIP_* into, not spray on.... silly people, giving them a market for this.... (I mean, I suppose there are probably use cases where dipping is impossible and the spray is useful. But for this use case? Dipping seems entirely appropriate. Ah well.)

Great, now I just need a Spectrum analyzer :|

[@EEVblog]

You scope likely has FFT

[@scienteer3562]

@@EEVblog or cheap RTL dongle or HackRf will work.

[@EnjKat]

As SpecA’s go, you can likely get the Rigel jobbie that Dave was using for ~1500 $USD or less. That’s serious coin, but WAY cheaper than an equivalent unit a decade ago...

[@TemporalRecall]

Yeah about $20 for the RTL SDR + Spektrum (free) www.rtl-sdr.com/poor-mans-spectrum-analyzer-with-an-rtl-sdr-and-noise-source/

[@scienteer3562]

@@samuelcomeau Install it with Pothosware. Dead easy.

[@erikgleber6652]

Another solution for your rubber coating: buy ABS filament for 3d printers and solve it in acetone. Then you can use a brush to apply it. The acetone vaporizes on its own at >20°C and only the ABS is left

[@Choober65]

That faint thudding at the end of the video is Tekbox executives jumping out of the windows.

[@vincei4252]

Dave, you need an x-ray machine. Just saying :-)

[@EEVblog]

Not possible to buy one here without a license.

[@vincei4252]

@@EEVblog ugh. That sucks.

[@zvpunry1971]

I like the type of x-ray machine bigclive uses ;)

[@vincei4252]

@@zvpunry1971 Bigclive has an x-ray machine ?

[@ahuad]

Hahaha I have a lot of different x-ray models at home and didn't know it.... Hilarious

[@TheMeddlingKidsHaunt]

It's funny that I don't have any use for the probe but found it so entertaining.

[@iceCOLDkillaxDLoL]

The guys at tekbox spent houndres of hours on r&d for this thing to work properly. Dave botches something together in 10 minutes and it works just as fine if not better than the pro kit. :D

[@khronscave]

R&D, or D&M (design & marketing)? :P

[@acrodrigues1]

Research & Development

[@SeanBZA]

Getting those curves that are individual, and that are a true reflection on the device, as opposed to lucky try and it worked. Plus the whole repeatable manufacture thing that means you can interchange probes, and not have to run a calibration on each new one you get, just use the curve supplied, which is well within a specified tolerance spread.

[@antoineroquentin2297]

*semi-rigid. You can't bend rigid coax without destroying it

[@EEVblog]

Yeah, correct.

@@EEVblog This cable is actually called "conformable" coax cable. Meant to be shaped for final application, but not for repeated flexing/bending. Good video. Thanks!

[@martinkrehl1478]

Yes you can. Like a plumber. Just not by hand.

[@allesklarklaus147]

Martin Krehl Yeah you could even bend it by hand if you're careful and keep your bend radius large enough. You could use a 10mm pipe/rod/drillbit shaft and bend it around there for example.. Depends on how big it is obviously, you're not gonna bend the 50mm (or so) stuff at the TV station

[@antoineroquentin2297]

Rigid coax often use air dielectric. If you bend them, you will change the impedance and risk the inner conductor touching the outer conductor. There are specific L-pieces for rigid coax, but often they are custom made anyway (soldered/welded). Rigid is really not meant to be bent. Dave has a nice video from a TV transmitter site where they had rigid coax pipes.

[@kapioskapiopoylos7338]

love all your videos, but i have a preference on EMC/EMI things, keep it up

[@1kreature]

You know you need to take this to the next level right? First you use a 3d printer as x/y scanning platform for the board (printer can be fed gcode for movements from pc via usb) and then record the data from the oscilloscope via for example python integration with scope (usb again). Recording the spectrum on each position in a grid and display everything in a nice overlay on a photo of the board. User could then either see a sum/max of all the emissions or scroll through the spectrum and visualize a frequency slice in the overlay. Now that's sexy!

[@EEVblog]

Yes, I said that in the previous video.

[@simonbaxter8001]

There is a product out there that is an array of loops in a paper sheet size bed. Its multiplexed and scanned into an analyser. You can put an image of the pcb layout over the scan data to give you an RF 'heat' image. Think its made by Emscan.com from memory.

[@1kreature]

@@simonbaxter8001 I know. I've used one. This is cheaper and more fun...

[@Bushougoma]

13:29 It looks like a tool handle dip to me 4:14 the surface finish is rough, bumpy, and full of holes. It's likely the same thing you used Plastidip and that shade of blue is one of the three shades they sell. It also comes in a can so you can dunk the part rather than spray it. Just just dunk the PCB into the container, pull it out, and let it drip dry. Repeat the process to thicken the coat.

[@killymxi]

Bushougoma Looks like they also used some primer coating to make rough surface layer on PCB and make it stick.

[@PixelSchnitzel]

I came here to say this is one of your best videos in a while and am amazed to see how many others are saying the same thing. I couldn't believe you peeled back that Tekbox cover; thanks for doing that!

[@arthurvin2937]

Now start mass production and sell it on Ebay for $50 and bundle it with calibration certificate "Calibrated by Dave".

[@lelandclayton5462]

A cal cert on a post-it note...

[@simonbaxter8001]

Are the 2 thumbs down from the CEO and Marketing Director at Tekbox ? Lol. Tekbox are so overpriced for what they are.

[@nraynaud]

I think you might be slightly wrong about the commercial probe coating. I feel like they did a grippy gritty transparent conformal coating to help adhesion of the blue shmoo.

[@EEVblog]

Possibly

[@clau2272]

we've always called that soldered braid stuff "semi-rigid" coax. Solid copper outer shield was called "rigid" ..

[@EEVblog]

Yes, it's semi-rigid.

[@NoahFect]

Actually the right term for this stuff is "handflex." Examples of semi-rigid coax would include the 0.086" and 0.141" cables with the solid tinned-copper shield that you see in commercial spectrum analyzers and other RF gear. It is not meant to be formed by hand and often breaks when you try.

[@MidnightVisions]

Those tiny amplifiers are the MAR series from minicircuits.com. They have been around since the late 1970's. This is the MAR-2 line. www.minicircuits.com/WebStore/dashboard.html?model=MAR-2SM%2B

[@JoseSilveira-newhandleforYT]

Seems to me that Tekbox is not at all pleased with this video :-)

[@Arielo.07]

Great video Dave! Could you do a similar frequency domain analysis with an oscilloscope's FFT? Just to make it a lot cheaper and accesible, since it's a more common tool.

[@LaughingBuffaloes]

I would love a video on using FFT function to make these measurements. I think building one of these probes would be a lot of fun for $10. A spectrum analyzer is out of the question for me, and probably a lot of hobbyist, but I do got a scope with FFT.

[@janbottorff4642]

You could potentially use fft on a scope, if you had a scope with 1+Ghz bandwith. A new 1Ghz scope is in the $10k vicinity. A hacked to 3.2Ghz Siglent spectrum analyzer is about $1700. A HackRF SDR is about $250, and I believe with the correct firmware sweeps 6Ghz rapidly. The lower cost devices would not be calibrated or have features like like tracking generator, so the hacked spectrum analyzer has some significant attractions. There are also PC based vector network analyzers, which add a lot of additional functionality, as they measure phase shift in addition to amplitude. A full duplex SDR + a ebay reflection bridge might be a usable vna with the right software.

[@kenchilton]

Use the PastiDip in the non-aerosol can or liquid electrical tape and you will be much happier. Also, you can make the very small loops from very small diameter coax. The coax does not need to be rigid, and if you put some steel wires or small fiberglass/carbon-fiber rods along side the coax for the small loop, it will add the needed rigidity. Use heat shrink over the coax and stiffener for the straight part and dip/paint on the liquid tape over the loop. The small loop can be even more finicky to cut and solder, so short the end of it back over the coax before bending it into the loop, then solder the whole end back to the shield to make the loop. To cut the gap in the middle, you only need to make a single slice, and when you dip it or brush on the tape, it will fill that slot and Robert is your mother’s brother.

[@russoft]

I may actually join the discussion over on the forum. We have billions of these DIY H-field probes in our lab of varying qualities. Might be rather entertaining to post a picture of all of them.

[@EEVblog]

Please do!

[@whollymindless]

Demonitized by Tekbox.

[@jovangrbic97]

For all those wondering the weird round package is a type 86 plastic package, and the amplifier, which has only GND, IN, OUT, is a MSA0486.

[@cowasakiElectronics]

Is it possible to get any sort of useful reading with a scope? I've seen these used for locating dead ICs

[@williambello4089]

I built an EMC probe for less than $8, using a toraial core coil and soic op amp. I needed to measure current WITHOUT physically touching the current-carrying conductor. Torrid core coil to the rescue! You can see it, and the printed circuit board CAD files that I offer as "open source", on my MeWe page @ Esp and IoT

[@DanShepherd72]

Nice video, one has to question why the commercial one’s are so expensive. It reminds me of when companies rub off chip numbers to hide how they are made. Probably also would reveal the company’s mark up vs actual part costs

[@adventcontrols]

All 9 Tekbox employees thumbs downing your video haha

[@WacKEDmaN]

them cheap amps are perfect to use for RTL-SDRs aswell..infact you can use this probe on a SDR and find the same results!

[@EEVblog]

Yes, they advertise them for that

[@TymexComputing]

Very instructive - thank you!

[@thomask77]

Please do a Rogowski Current Probe next!

[@wombatillo]

You can make the H-field loop solder connection and shield cutting in many ways. There will be very little performance difference if you make it unsymmetric and just solder the center conductor to the shield on one side. Yeah, it won't be geometrically symmetric, but it will be electrically almost the same as the more complicated construction.

[@DoRC]

Semi rigid

[@EEVblog]

Yes, I meant to say that, but my aussie mind shortens stuff.

[@gregvisioninfosoft]

When winding the coils I am desiring to measure to very low frequencies. I notice professional low frequency sensors such as 'WaveControl WPH-DC' are extremely expensive. What limits the lower frequency response of these? How many loops and wire gauge if my goal is to be able to measure down to 1hz?

[@ayubjamil2615]

Steve Irwin of the electronic jungle.

[@stevetobias4890]

Not sure why you have a few thumbs down. A huge money saver that will give the same performance. This is great Dave. Thank you yet again

[@conorstewart2214]

The thumbs down will be from the company that makes the probes or from people who bought the probes and now feel like they wasted their money.

[@kyoudaiken]

Feels like those $300 ones are a total ripoff.

[@redoverdrivetheunstoppable4637]

they are but little selling things pay manufacture "pay day" style and they do that for you, sooooo....

[@risvegliato]

Well.. Maybe but not really. the 300 dollar ones will have guaranteed and certified performance. You can make one yourself, and it may perform in a similar way, but it's not certified. Your customers need traceability.

[@Futschikatores]

Many customers don't need traceability. They need a working product.

[@redoverdrivetheunstoppable4637]

@@Futschikatores i'm not sure how many people buy this kind of things but i bet they are little, you can't pay a device so particular like 20$ just because it's the deserved price, the manufacturer can't maintain that product with THAT costs mind the case of STM32 microcontrollers, look the one on the "blue pill" thing, it's given for 64kB of ROM but they are all 128kB instead, that's because the cost of the more memory they give you for free is LESS than the cost of different lithography masks (one set per device ramification model), so they give top-line of that chip to everybody ,just changing the ID with a laser (i think)... this case is the same but obviously on the shoulders of customers (that's my interpretation but i like to pay my things the correct price like all of you)

[@ProdigalPorcupine]

risvegliato - Certified and guaranteed to do what, though? This isn’t a calibrated tool, it just sniffs out radiated emissions and gives relative readings. The levels are dependent on the probe’s proximity to the source, there doesn’t even need to be close tolerances from one set to the next. It just has to show something when connected to a SA or scope. It’s priced so high because it’s a niche product that isn’t expected to sell many units. A Chinese company with much lower overheads could probably knock these out at around 20-30 USD a set.

[@Herby-1620]

While the $10 option is VERY useful, the $300 kit has all sorts of calibration graphs and "reproducibility" when you get it. It might not be necessary in ALL instances, but if you are doing a nice funded project that HAS to meet specifications, you may need the $300 option. For me the $10 option will get me there for over 99% of the time.

[@EEVblog]

The thing with near-field measurements is that you are not doing quantitative absolute measurements, so the point is a bit moot for most cases.

[@mrtechie6810]

But wouldn't you use an anechoic RF test chamber for calibrated EMC tests? Would the 300 dollar calibrated probe be the measurement antenna?

[@mekatronikorg]

I'm sure it would be possible to build a $50 active probe that performs close to a $5000 keysight active probe. But the problem is, in order to do that, you need a very expensive spectrum analyzer and all related RF electronics gear. And once you have invested $100,000 dollars for all that gear, you wouldn't want to sell the product with just say a 100% margin, cause if you do, it would take decades to amortize your investment.

[@pablodv87]

As someone else said on the comments, I'd like to see how an oscilloscope FFT using this probe compares to the spectrum analyzer, for the ultimate thrifty EMI measurements!

[@gixerags750]

Hey Dave , help save a fellow brothers life regarding working on high CRT voltages. , I was told that those Tradie ARLEC /HPM (ORANGE EARTH LEAKAGE PROTECTED ) power boxes can save your life but not the equipment??? Your thoughts,,??

[@davidbrewer7937]

We always made our own probes like this. You can make them more selectable by adjusting the size of the loop.

[@dvlachy]

Hi guys. I created a 3D PRINTED CASE for the amplifier mentioned in Dave's video. For people interested in: www.thingiverse.com/thing:3490143

[@stephencampbell9886]

So I can use this to get the signal from the speaker wire on my Panasonic SA-PM46 Self Stereo (which I purchased from JB-HI-FI Woden in Canberra in 2007/08) amplify it so I can use it as line in for my TDK S60 Tremor Subwoofer!

[@stanburton6224]

Ok, im about to ask a REALLY stupid question, what is "H" field? Magnetic? E field I presume is electric field.

[@redfishervictoria]

When I play our video at 2x speed you become an electronic squeaky madman!

[@EEVblog]

Play it backward... Dave is dead...

[@ThomasHaberkorn]

let's say far field measurements come back with a high spike at 200 MHz. Will the near field probes (E or H) also see a spike at 200 MHz ?

[@freelectron2029]

HELP. i have tried to join your EEVfORUM with out success i signed up for a new account but never received a conformation email. SMF help section says if i try to login with out conforming my email it will say i have not confirmed my email and will show a link to re send the confirmation email. this is not happening when i try to login it just says username does not exist and asks for a correct username. this is very frustrating as there is no way to contact any of your administrators unless i am signed in. why is this happening, how can i fix it,

[@willyarma_uk]

That was ace, enjoyed that. I was thinking u could 3D print a mould for the coating.

[@barrykery1175]

Great video. Question: "How many volts are needed to power the Low Noise Amplifier?" Barry

[@simonbaxter8001]

Dave, what happened to the 'affordable' EEVBlog PCB based near field probe project??

[@7th_dwarf542]

can anyone comment on the signal symmetry delivered by these antennas? The coax cable has 50 Ω wave impedance matching that of the amplifier and the scope, but is the signal coming from the probe symmetric or single ended? Feel free to bash me in case my question makes no sense. Thank you in advance for taking time to answer my question.

[@Shabbymannen]

That piece of coax is beautiful.

[@dwalden74]

Will this help to find conducted emission problems, or only radiated emissions? I’m looking for a way to debug my conducted emissions issues.