Hi
You may know that after latest Source SDK many people started having troubles with Moder Browser. The problem is you can't type some symbols in the 'Filter' area.
To be exact, the only characters you can enter in this field are:

Smalls: abdefgijklmnopqrstvwxyz
Capitals (using Shift): FHIJKNUY
Capitals (using Caps Lock): ABDEFGIJKLMNOPQRSTVWXYZ
Numbers: 1234567890
Specials (not needed, but whatever): !@#$%^&*()_=-+\/'"><.,?~

The register of symbols makes no sense, so you don't need capitals while searching something in Filter field. But we miss some small characters: c, h and u

How to type 'h' or 'u'
Just hold the Shift and type uppercase 'H' or 'U'. As said before, the size of the symbol makes no sense for the filter.

How to type 'c'
It's a bigger problem, because you can't type even uppercase 'C' using Shift or Caps Lock, so the solution will be a more complex: ALT+99
1. Hold ALT
2. Press 9 (nine) on the NumPad twice
3. Release ALT

I guess you are able to search for any model you want now ;)