Re: Curved CRTs?


 

On Fri, 29 Dec 2017 01:16:25 -0800, you wrote:

On the other end of the extreme I recall reading about the US-Russian
nuclear reduction exchange, and the US showing the Russian inspectors the
"fast" US scopes and them being somewhat unimpressed because it turns out
the US scopes had to fit in a rack mount which limited there size and thus
length, deflection and speeds, The Russians used long 6 foot (might have
been 2 meter) CRTs tubes and a dark box to put you head in to get multi GHZ
scopes.

Can't seem to find any links

John
That is one of the great stories to be found on the list. Here is
what Steve had to say in his message from Sun, 26 Aug 2012:

The Russian scopes certianly leveraged the design topologies, but wre their own designs. In some cases, they actually exceeded Tek's performance, lending to the designs were done much later, when higher performance components were available.

For the transient digitizers (regarded at the time by the US state department as some of the crown jewels of the nuclear weapons development) it was embarassing to find out that the Soviet technology was MUCH further developed than Tek's. I was working in the division that developed the digitizers at the time. At the end of the cold war, there was actually an exchange where the Soviet nuclear weapons designers came over to watch a US test, and our scientests did the same, going over to watch one of their last tests. When their scientests came here, the researchers at EG&G (who the government contracted to instrument the test shots) assumed that they would be wowed by the 5 GHz digitizers that Tek provided. They were not. Instead of asking how we built such fast digitizers, their only question was how do we drill the holes in the rock for the tunnel so smooth? They used dynamite to carve their test tunnels, leaving a broken rock face.

Their digitizers at the time worked at 13 GHz. The secret? The problem with building very high speed CRT deflection is charging the capacitance of the deflection plates. To get decent deflection angle, it takes a few volts/div. That is a lot of current to pump into and out of the plates which act as capacitors. So the Soviets kept the deflection angle down. Way down. Their scan converter CRTs were nearly 6 meters long! The US government labs made a requirement that the digitizer must fit into a standard 19" instrument rack. This "artificial" restricion limited Tek to 5 GHz, and even achieving that took a lot of technology development!

Their pragmatic approach allow them to achieve may things we struggled hard with in the US.

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