Shielding

As many mentioned on the importance of shielding in all kinds of oscillating electronics, I attempted to do something for my RTL-SDR to prevent local FM and TV stations overloading directly the front-end. As RTL is a bit weak on selectivity and lacking a proper tuned front end (being a wide band receiver) it's important to shield front end.

Also, the 28.8 mHz crystal clock oscillator on cheap rtl-sdr dongles are not shield grounded, as opposed to many practical electronic products.

So what i did was simply this:

For disassembly and other ideas, this gentleman has quite nice posts on his blog.

Being a poor-mans-shield, the shielding material was cut from some tin candy can. Can be easily cut with a pair of scissors. Be careful since the edges become razor sharp.

When shielding, make sure no metal part touch the board components. If you want to go fancy, you can cut a tab just above the RTL chip and using some thermal grease, you can create a heat dissipating rf shield. About heat profile of these little IC's some smart gentleman did some thermal imaging.

Then comes shielding the whole thing. The important detail of grounding/shielding a USB devices is quite subject to debate as the shield on USB cable is connected to the ground of the RTL dongle board. This breaks down to this: shield picks up all noise from your computer or laptop, carries it to your dongle. So i simply removed the shielding as the dongle board is connected to V- of the USB cable.

Using the same tin can material, i cut the following.

The box is a simple plastic box from a minimag lite flashlite (which is magnificient product, by the way)

Inside box is the tin can shielding material.

Just use your creativity for making the box. Just a reminder, to solder tin, make sure you clean solder area with sandpaper until shiny metal appears.

With the small hole for soldering the antenna connector. Sadly, I don't have a photo of the dongle inside the shield. I'll upload once I open the case.

(More to come)