YG520C Desktop shielded chamber  - Page 1
Forum section: electronics / testgear

author: TopQuark
author_rank: Frequent Contributor
timestamp: July 22, 2022, 09:06:13 pm
content: Not sure how much interest there is in this kind of equipment, and not sure if this strictly qualifies as test equipment, but I thought this is quite test and measurement related so I'd thought I'd place this here.Recently I was developing a very low noise circuit that I have to characterise properly and I had a lot of trouble isolating the DUT from external EMI to make accurate measurements.Also I haven't been very happy with the noise floor of my conducted emission measurements, as doing such measurements in open air picks up a lot of EMI not originating from the DUT.I have tried DIY solutions with various metal boxes/enclosures, but I haven't been happy with the results. There's always some leakage into the test chamber, and EM reflections within the chamber messes up the measurements I am trying to make.So I decided to "invest" in a more proper and professionally made solution, and I found these desktop sized shielded chambers for sale on Taobao. These shielded chambers are marketed towards portable RF equipment (smartphones, radios etc.) testing and characterizing.I settled on the YG520C model, with the following specs:- Outer dimension: 380x340x260mm- Working volume: 350x320x240mm- Weight: 12kg- Shielding performance: >80dB (800 MHz to 6 GHz)- Ports- 2 x SMA- 2 x N- 1 x DB9- 2 x USB- 1 x RJ45- 1 x DC barrel jackThe unit cost around 450 USD and is also quite expensive to ship around, so it is not an insignificant purchase for a home lab. However, with the time and effort I have sunk into making a proper shielded chamber, I think this is a sensible purchase if it performs as well as it advertises.I'll be testing the chamber more and documenting the results.

author: TopQuark
author_rank: Frequent Contributor
timestamp: July 22, 2022, 09:25:38 pm
content: So some rough measurements just to see how well the shielded chamber shields against external wireless signals.I used a wideband antenna, and made some measurements with the antenna inside vs outside the chamber.Trace A is antenna outside of the chamber, Trace B is noise floor of SA with no antenna attached, Trace C is antenna placed inside the chamber. Pos peak detector is used, traces are max hold results from around a minute of measuring.While I am not able to verify the 80dB shielding performance spec, what I got is already a huge improvement compared to my previous DIY attempts.

author: TopQuark
author_rank: Frequent Contributor
timestamp: July 22, 2022, 09:51:32 pm
content: The other application and test I have in mind for this shielded chamber is for conducting conducted emissions EMC measurements.I performed two conducted emissions test, one inside and one outside of the chamber. I used a 12V battery as a power source, and a power potentiometer as the DUT to make sure I am measuring the noise of the setup itself, not the power source or DUT. The LISN and battery was placed on a continuous conductive surface, the DUT (potentiometer) is placed on a 5 cm tall block of foam above the conductive surface.Trace A is test done in open air, Trace B is test done in the shielded chamber. I couldn't be happier with the results.