[RFI] RF tight rooms - somewhat OT

[Roger (K8RI)]

On 5/11/2013 11:34 PM, n0tt1 at juno.com wrote:
> Hi Gents,
>
> I know a crystal radio enthusiast in CA that lives near
> a 50KW BCB radio station.  He's been having trouble
> making Q-meter measurements on some of his hi-Q
> coils using a HP Q-meter.  He's been making
> experiments with various shielding methods
> using an AM BCB portable radio as a detector.
> He says that the best he's found so far is aluminum
> foil, as long as the "seal" is tight.
>
> To make a room that is large enough for him and a bench
> takes a LOT of foil.  The floor, ceiling, walls, floor and a
> good seal on a screened door would be needed for a
> really good RF room.  The power for the room would also
> have to be filtered or he could use a computer's UPS.  The
> shielding would be grounded, and the shielding, whether
> it's say, chicken wire, AL screen, etc would have to be
> bonded together at the corners.  Then the door would
> have to be sealed as well (maybe metal weatherstripping
> for that?).
>
> My question to the group is what, in your opinion, is the
> best/cheapest RF-tight test room he could build for himself?
> Has anyone on this list done that?


Many years ago, in another life, (I spent 26 years working as an 
Instrument tech, I did instrument calibration traceable to NBS.
My work area and desk were inside a double wall screen room.  Thia was 
about 20 X 10, or 12 feet,  The door was likewise double wall, with 
what looked like large finger stock all the way around each layer. The 
"fingers were about 3/4 or 1 inch wide and maybe 1.5 inches long.  The 
door "cam locked" shit with about a 2' handle on the cam.  The room was 
constructed out of panels that were ...Guessing...about 4' X 8" and 4" 
thick. Frames were either brass or bronze as were all bolts were 1/2" "I 
think".
All electrical came in through a "filter panel" for lack of a better name.

We could stand just feet apart with 10 watt HTs and still hear each 
other with the door closed, but not camed shut.  As the handle was moved 
you could watch the S-meters go down until no signal was left with the 
cam fully closed

This was a commercial system. Not exotic, but very effective for an example.

73

Roger (K8RI)
>
> 73,
> Charlie, N0TT
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