[GreenKeys] Low level TEMPEST teletype interfaces

[telegrapher at att.net]

 I had one of those machines here a couple of years ago.  The leads to and from the keyboard contacts and some other stuff was in small metal tubing.  Don't know what else as i've forgotten most of what i saw.  Sold it to a "foreigner" back on the east coast.  

Larry
W0OGH


  -------------- Original message from John Nagle <nagle at animats.com>: --------------


> > On Jun 26, 2009, at 12:07 AM, Bob McConnell wrote:
> > 
> >> Roy Morgan wrote:
> >>> ... I have in storage a Model 28 that I think is set up for low   
> >>> voltage/tempest operation.
> >> Internally, the M28 still used 60 mA loops to the selector magnets.  
> >> Tempest introduced an external circuit that was +/- 7 volts at less  
> >> than 1 mA.
> > 
> > Thanks to all who have replied with personal experience and other lore  
> > about the Tempest Model-28's.  As is my habit, I've archived all this  
> > info and will dig it out once I unearth the unit I have (a KSR) from  
> > storage.
> 
> For NSA background information on low level Teletype circuit operation, see
> 
> http://www.nsa.gov/public_info/_files/cryptologic_histories/history_comsec.pdf
> 
> This report from 1966 details how signals were intercepted from the inductive
> kick in Teletype selector magnets, and how hard it was to stop that.
> 
> 					John Nagle
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html