[TowerTalk] Fwd: Fwd: Shielded shack

[Roger (K8RI) on TT]

On 9/30/2013 12:28 AM, Grant Saviers wrote:
> snip
>
> The one experience I had with a homebrew metal window screen cage 
> (copper or bronze, I forget which) was that it didn't work very well 
> because the wire crossings really aren't solid electrical contacts. 
> The fix was to have a tech solder them in a 6" grid of X-Y lines - ugly!


Copper, or bronze window screen works very well.  The edges are fasten 
to brass angle forming panels instead of fastening screen to screen. 
Then the panels are screwed together about every 3 inches. The door was 
of like construction that used finger stock to make contact and the door 
was cammed shut.

The screen is sandwiched between the angle and a 1/8th by 1" strip of 
brass or Aluminum

You could watch the isolation go down as you loosened the pressure of 
the cam even though the door was still making contact.

I mentioned working in a screen room like that and it describes the 
panels quite well, other than the fact that it was double walled. The 
isolation was beyond the rang of me equipment down to at least 160 KHz.

If I wanted to build a shack at the base of the tower, I'd use the #3 
rebar grid I mentioned before and build a set of screen panels to go 
inside the grid,  I'd probably use aluminum screen and Aluminum angle to 
save money.
It still wouldn't be cheap.   Then finish the inside with normal 
construction and cover the exterior with vinyl siding for appearance.  
With that construction, the SPG, or common point if you wish, and the 
leads properly filtered and bypassed, it should be a safe and RF quiet 
shack.  The rerod grid and screen would also tie to this ground.

73

Roger  (K8RI)