5 Oct
2005
5 Oct
'05
2:01 p.m.
Subject: Re: CRT implosions (was: Re: "screen mold")
From: William Donzelli <aw288 at osfn.org>
Date: Wed, 05 Oct 2005 15:34:56 -0400 (EDT)
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Fact Check...
There were a few that used elctrostatic that were not PPI but time domain.
There were a variety of radars used some very crude appearing by most
standards for display. A few the CRT was simply a scope doing TDR on the
radar pulse and it was the operators duty corrolate the antenna position
with the displayed reflection. There was at least one airborne system that
used two smaller tubes to display azmuth and elevation based of one
transmitted source and two seperatly recived returns. By late war there
was considerable evolution in radar types.
There were also airborne landing aids systems that were crt based as well.
I used to see them on Cannal st NY back when 1$ was a good hours pay.
Fun stuff really as much of it can be duplicated in miniature using
current tech at 10ghz.
Tubes typical of that era was the smaller
electrostatic types and 5up1/7
were of the era.
Electromagnetic (and combo) tubes were just as common starting in the
1940s. If a tube had a P7 phosphor, it was likely intented for PPI duty,
and nearly all PPI scopes of the era were rotating yoke types. 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.
Graticle thickness not far thicker than the tube face in many
instances. Most actually were probably thinner. They varied from 3/16
inch to just a very thin sheet, maybe just a few thousandths thick. Tubes larger
than about 10"
didn't appear much till the mid 50s.
12 inch tubes were very common before 1950. Just about ever World War 2
Allied air search radar had one (or in the case of late war types, two). 
5 Oct
5 Oct
7:55 p.m.
There were a few that used elctrostatic that were not
PPI but time domain.
If you are talking the A-scope (and variants), well, "a few" being
"most" when it comes to pre-1950 radars. The A-scope was the tube that was
used to get ranging information, using a cursor connected to a mechanical
counter (yes, the origins of the mouse, folks). Anyone that pulled range
off a PPI tube was given KP duty peeling potatoes.
There were a variety of radars used some very crude
appearing by most
standards for display. A few the CRT was simply a scope doing TDR on the
radar pulse and it was the operators duty corrolate the antenna position
with the displayed reflection.
A quick glance at the azimuth indicator, a real time selsyn dial, would be
all the correlation required. The most correlation would be for the very
earliest radars, and that would be yelling at the azimuth operator to give
you a reading.
There was at least one airborne system that
used two smaller tubes to display azmuth and elevation based of one
transmitted source and two seperatly recived returns.
The two scopes were a B-scope and a C-scope. They show different
projections (very handy for intercept, as the operator could
construct a 3D image of the airspace in his head). The radars you are
talking about use only one scope, and the receiver timeshares the
scope. None of the early lobe switching radars used two scopes (unless
one was just a repeater).
There were also airborne landing aids systems that
were crt based as well.
I used to see them on Cannal st NY back when 1$ was a good hours pay.
I see these scopes all the time, as I collect radar gear.
Yes they did. But not all. Airborne systems were
prone to mechanical
shock and that was a known thing. Having a radar fail was nearly as
serious as damaging the trained operator.
What does this have to do with graticle thickness?
key words, "appear much" as in not
commonplace but did exist. Even the
military had inerta.
No, they were common, even fairly early into the 1940s. Even the 12 inch
P4s for television were available in good numbers.
William Donzelli
aw288 at osfn.org
6799
days inactive
6800
days old
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