Help!

I am looking for schematics for circuits to "jam" TV and CB reception.
I am interested in "jamming" reception on my property only, so the "jamming
device" needs to be really low power - only capable of "jamming" an area about
half the size of a 'small' city block.

I read about a circuit that transmits white noise from something like 25Mhz to
something like 30Mhz - effectively "jamming" reception. Any pointers?

I also read of a circuit that used a crystal detector and would only "jam"
after detecting a transmission! Anyone have any info on this?

The closest I have found so far is a reference on Google (dejanews) to
"s_jam.jpg", but there are no pictures there, so I cannot see the schematic.

Any information, schematics, or pointers to web sites would be greatly
appreciated!