[GreenKeys] tempest stuff

[gil smith]

Hi Bob:

This tempest radiated-emission talk has me kind of curious now.  Did you do
some of that testing?  Hmm, lots of questions pop to mind.

When you say a horizontal dipole, what was the total length (a TV dipole is
cut for 66MHz or so I think).  Was there a balun involved to get to
50-ohms?  If I remember correctly, a vertical antenna has about a 50-ohm
feedpoint, a dipole has about a 75-ohm feedpoint, and a folded dipole has
about a 300-ohm feedpoint.  But I'm a bit confused, since the TV dipole I
just peeked at has 300-ohm twinlead coming out, and I doubt there is a
balun inside.

What bandwidth was of interest for the testing, and what frequency region
had the highest emissions?  What instrument was used for measuring?

thanks,

gil


At 11:32 PM 1/23/02 -0500, you wrote:
>Hi Gil,
>
>You may have trouble measuring it, unless it's way out of specs. The 
>requirement was no more than 1 micro volt p-t-p measured on a dipole 
>antenna one meter from the open front of the cabinet. If all the shielding 
>is grounded correctly, and there's no significant corrosion, this low 
>emission level was quite easy to maintain. If you can find a set of rabbit 
>ears off a small TV that allows the two elements to open up to 180 degrees, 
>and replace the 75 ohm or ribbon cable with six feet of 50 ohm, you will 
>have a pretty close approximation of the antenna we used.
>
>Bob McConnell
>N2SPP


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