Electronics > RF, Microwave, Ham Radio

EMC equipment: Coupling-Decoupling Networks CDN DIY, EN 61000-4-6

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piotekp90:
Hi,
The price of EMC-related instruments can cause headaches. Therefore, why not try to build some EMC equipment yourself, such as coupling-decoupling networks, especially if you have a vector network analyzer. After reading the information in EN 61000-4-6 standard, I decided to make the CDN M2, M3, S24, and appropriate calibration adapters myself. I used Wurth ferrite cores 74272251, 74271221, 7427153, 74270044, Vacuumschmelze core T60006-L2040 and Kemet PME 271 Y2 series capacitors to make these. The CDNs are based on the GAINTA BS 39MF aluminum enclosure. On the EUT side, the front of the case was cut out and the 3D print was screwed to it. For attaching the cores, a base was printed which further reduces the parasitic capacitance between the housing and the wires inside the CDN. The measured impedance values are within the range provided by the standards in 150 kHz - 230 MHz range :) The HP 8753E vector network analyzer was used to measure the impedance, along with adapters suitable for the type of CDN.

30W broadband RF amplifier in the 100 kHz - 230 MHz band under construction - I will share the results once I have developed the final version;D

There is a CDN RJ45 waiting in the queue to be built, if anyone has pictures of the inside of this type of network then please contact me or share pictures  ;)

piotekp90:
CDN M2 and S24 USB C

Vtech:
WOW! Great build!  :clap:
Exactly what I was looking for. Maybe a bit too professional for me :-DD.

I started by bodging together a 50W RF amplifier. Mine is a piece of crap but should do the job after calibration. It is based on some ancient RACAL military amplifier overdriven to the extreme and a Chinese 2W amp as a preamplifier.


This thing can work from around 7MHz up to 80MHz. I don't need more. Problems only occur above 10MHz and I don't have to test above 80MHz.
I already managed to fry a scope probe with it (guess what, scope probes can't handle the RF power :-BROKE)
It is quite non-linear and generates a lot of harmonics but should be enough for recreating the problem found in the proper EMC lab.

Now I need to bodge together a 6dB/50W attenuator (easy) and this M3 CDN which is some devil's invention (the hard part). My CDN probably won't have a case and will be heavily inspired by the photo found in the EMC Standards guide (linked below).

You've probably already seen this guide but I'll leave it here for others: https://www.emcstandards.co.uk/files/61000-4-6_immunity_to_conducted_rfi_2_1.pdf
There is also this useful article: http://www.elmac.co.uk/PNP_61000-4-6-a.pdf

A company called TEKBOX from Vietnam has a lot of cheap EMC equipment. It is really nicely designed and manufactured but a lot cheaper than professional stuff - good enough for pre-complience. I use their LISN for emissions and it's great.
They have a useful manual for their CDNs: https://www.tekbox.com/product/tbcdn-m3-coupling-decoupling-networks-m3/

nctnico:

--- Quote from: piotekp90 on August 06, 2023, 05:10:40 pm ---CDN M2 and S24 USB C

--- End quote ---
Thanks for sharing!  :-+

wilhe_jo:
Hmmm... Quite a lot of ferrites... I have a quite simple "Kit" for my CDNs... Just 2 cores of cable for 80MHZ... 2 or 3 random 100MHZ clap ones get it to 230MHZ.

I get you the part numbers.. in the end the core component is an epcos smps core :)

73

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