Peter: "Apropos attenuation, any idea why a cellular phone works perfectly (S meter at 3 of 5 ?!) in a 4 x 2 x 2 meter welded steel safe with the door closed? Not all the seams are welded perfectly (this is not a submarine) but there are not enough bare wires to conduct the cellular signal inside at that level I think ?!" I once tested a "screen room" where facilites had simply run a LAN connection into screen the room WITHOUT A FILTER. By placing my 2-way UHF ham transceiver next to this LAN wire I could bring up the UHF repeater that was on-site. All other facilities connections (AC power) were through filters. Standing in the *middle* of the SR - it was not possible to 'hit' the machine. I suspect that much of your 'leakage' in the safe was owing to poor contact around the door of the safe - that coupled with perhaps, a nearby cell site. All it would take is three or four inches (at that frequency) of even 'poor' metal to metal contact from the door to the body of the safe and you have an 'aperature' through which RF energy can propagate. Was there on-site "cell extender" (bascically two cell-band amps, appropriately duplexed, to create a bi-lateral amplifier like the dB Products "Prism" series) with one of the coverage antennas placed nearby the vault? I offer this as a possible reason - not knowing where your 'vault' was or the signal level outside the vault ... Jim ----- Original Message ----- From: "Peter L. Peres" To: Sent: Monday, August 27, 2001 4:31 PM Subject: Re: [OT]:Microwave Oven > > choke joint > > Yes but not 1:1.4E6 attenuation in one step. They usually have several > impedance steps afair? In my non-extensive experience achieving >50 dB > attenuation of nearly anything in 'one step' is no go (assuming it is not > tuned). Untuned one-step attenuators seldom go beyond 30 dB assuming that > they are to be reproducible and untuned. > > Even a simple cover joint with wire-clad gasket has two or three steps > (depending on how you count). > > Apropos attenuation, any idea why a cellular phone works perfectly (S > meter at 3 of 5 ?!) in a 4 x 2 x 2 meter welded steel safe with the door > closed? Not all the seams are welded perfectly (this is not a submarine) > but there are not enough bare wires to conduct the cellular signal inside > at that level I think ?! > > Peter > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.