5 Oct
2005
5 Oct
'05
7:18 a.m.
Subject: Re: CRT implosions (was: Re: "screen mold")
From: Paul Koning <pkoning at equallogic.com>
Date: Wed, 05 Oct 2005 09:44:09 -0400
To: cctalk at classiccmp.org
Tubes typical of that era was the smaller electrostatic types and 5up1/7
were of the era. The aviation tubes used for that airborne radar were
surrounded by a mumetal shield to keep mag fields out and the graticule
was far thicker than the tube. tere were really two generations of
tubes used the first ones were the fragile O'scope types and later
there were special heavy glass/metal types. Generally It's rare to
see a CRT exposed enough to be a hazard as there is always a case
(if for HV only) and some kind of graticule. The actual expections were
small O'scopes (O1) and hobby scopes. Tubes larger than about 10"
didn't appear much till the mid 50s.
Getting face full was unlikely due to the graticule and general
consturction.
I still have a bunch of 2AP1s (2" round green), 3BP1s (3" round green)
for projects. These are old tubes (ca 1953/55 date codes!). I also
have a modern D170 (2.2x1.8 rectangular) for some project..
>>>> "Tony" == Tony Duell
<ard at p850ug1.demon.co.uk> writes:
>> > I am told, BTW, that several radar operates in planes in the
>> last war > were killed when the plane had a heavy landing, the
>> radar display CRT > imploded, and they were litterally shot in the
>> face by bits of the > electron gun. But larger flat face radar tubes appeared in the 1960s
if not
earlier. The CDC 6000 series console (DD60) uses a pair of radar
tubes, with electrostatic deflection. I'm not sure exactly how big
they are, but certainly not less than 12 inches. They were probably
at least 2 feet long. Deflection voltage is around 2 kV, supplied by
an amplifier chain ending in a 3CX100A5 microwave transmitter tube.
Actually earlier, the SAGE system used a larger 12 to 16 inch round
with a 10-12KV Accelerator. Heck look at the tube used for the PDP-1
Console.
The radar tubes used until maybe 5 years ago at US air
traffic control
centers were at least that big, possibly bigger, and also flat.
Those were bigger flat face ARTS 1 and II series. If memory serves they
were in the 19-21" range.
The fragile portion of CRTs is always the neck area. The risk with
implosion is the neck/gun assembly will be propelled foward through
the screen if the screen shatters. When I was younger I'd scrounge
old TVs for the componenents. The CRT being useless to me would get
taken out back and put in the junk hole and a big rock heaved in. If
it was put in neck first and the face crushed the neck/gun would be
propelled 10 to 15 ft on a good shot to a large 19" or bigger CRT and
the glass widely scattered in a 10ft or so radius, we avoided that
as that meant raking up the remains.
The real hazard and I got to see this once is foolish people transporting
CRTs without making sure they are properly discharged. One case I did
see was a doof carrying a 12" by the neck, minor cuts. The other was
a fool carrying a tube from a H1500 terminal. He was careful supporting
it but the face with the neck upright. However the HV was still undischarged
and found it's way to his chest. CRT was dropped straight down and the neck
rebounded off the floor and went straight up into the rooms ceiling tiles.
Minor cuts to the lower legs, very lucky. Took a while to sweep that mess
up, there was glass everywhere.
Allison