RFI Shielding RTL-SDR with Blue Anodized Aluminum Enclosure

I currently own two NooElec RTL2832 + R820T2 SDR's that I use for spectrum scanning, and to trunk scan my local public safety radio calls that are always broadcasting (police, ambulance, fire, transit calls). I'll post more about that in a separate topic though.

http://www.nooelec.com/store/sdr/nesdr-mini2-rtl2832u-r820t2.html

The RTL-SDR stands for Realtek-Software Defined Radio because it is based on the Realtek RTL2832U chipset. These are very cheap $20 devices that can be used as a computer based radio scanner. More can be read about them here: http://www.rtl-sdr.com/about-rtl-sdr/

These devices are however vulnerable to RF noises/interference, which can affect the noise floor and receiving capability of remote signals. The screenshot shown above was my SDR receiving signals in VHF, around the 130-140 MHz band. The noise floor was seen to be around -40dB.

A user named will1384 on reddit has put together a gallery of test results that he obtained after trying different methods of RFI shielding: 

https://www.reddit.com/r/RTLSDR/comments/2k7qxz/i_put_my_rtl2832u_r820t_sdr_into_a_metal_case_it/

Image gallery + his findings:

http://imgur.com/a/pQ8dM

One of his methods was using a blue anodized aluminum enclosure like this one off eBay:

http://www.ebay.ca/itm/251467377857?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

...so I bought two of these enclosures to see if it would have any effect. However, as he shows in his imgur gallery, I decided not to ground the USB PCB connection to the case like he did.

eBay aluminum enclosure and RTL-SDR casing taken off

Measured out where to drill a hole for the MCX connection on the SDR to fit

SDR was slid and snapped into place afterwards

One of the side plates needed to have a cutout for the USB to stick out

Final assembly

Times two

Hooked up to PC along with an antenna for each SDR

Final Result:

NooElec SDR in OEM plastic casing. Noise floor: around -40dB

NooElec SDR in blue aluminum enclosure. Noise floor: around -42.5dB

Although not too obvious, the noise floor did seem to drop by a few decibels. To improve my reception in the future, I plan to purchase a set of LNA's (low-noise amplifiers) to help pick up farther away radio signals.