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Old 25th May 2020, 8:35 pm   #15
Craig Sawyers
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Join Date: Nov 2010
Location: Oxford, UK.
Posts: 4,941
Default Re: Code-Breakers:Bletchley Park's Lost Heroes

I can't remember whether I mentioned it before, but I restored BP's Lorenz SZ42 (the one they kept showing in the programme) to full functionality.

It was fascinating for a number of reasons. First was the selectors were Teletype manufactured, and many of the fixing screws were US thread. In fact before Teletype was Teletype it was the Morkrum-Kleinschmidt company and had strong links to Germany. So the SZ42, that caused so much hard work at BP had many parts that were made in the USA. Another quirk was that the transformer and choke were wound with SWG wire guage, for reasons I never found out.

I knew Tony Sale very well, and his charming wife Margaret (who sadly died in February this year).

Tony arranged a Cipher Challenge in around 2008. I went out to the Heinz Nixdorf museum in Paderborn with the SZ42 as the German end of this. We sent real codes from the SZ42, and the local ham radio club sent the cipher text using the correct modulation scheme and transmitter power. The challenge was for someone to intercept the transmission and break it before it was recieved at TNMOC on AR88's, converted manually to punch tape and broken with Colossus. A guy in Bonn broke in 20 minutes whereas Colossus took 40 minutes.

Last time I got my hands on the machine was just before the cipher challenge. I was working on a bench behind the thyratron counting rings, taking the entire cipher wheel assembly to pieces and re-greasing it. That rack of valves is like sitting behind an electric fire!

In fact the ladies who used to operate the 5 colossus machines used to strip down to bra and knickers in the summer to keep cool. The blokes used to draw straws to decide who took in the punch tape for the next machine run.

In point of fact the SZ42 you saw in the programme was still at TNMOC and fully working. But as part of the Paderborn trip, the mains transformer burnt out (it was already I replacement I had had wound earlier). I had it remanufactured a second time, but before I could fit it BP took command of the SZ42 from TNMOC and put it in a glass case. I still have the transformer, and the WWII original fittings on the top of my wardrobe.

TNMOC now have a partial SZ42 on loan from Norway. But they have absolutely forbidden any restoration. Even though the (ISO standard!) bearings are pretty much siezed, they viewed the old tar like grease as being an historical artifact. Weird, but there it is.

Craig
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