CRT question


Mark Anton
 

I was wondering why on so many of these old scopes, that you are only able to use so little of the screen, Like 4 or 6 divisions. Why not the whole face of the tube?

Thanks Mark Anton.





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Jose V. Gavila <eb5agv@...>
 

I guess it is a matter of geometry. I have seen older scopes which used all
the display and, well, what you saw at the edges was just an approximation ;-)

Regards,

JOSE

At 01:50 18/02/2003 -0600, Mark Anton wrote:
I was wondering why on so many of these old scopes, that you are only able
to use so little of the screen, Like 4 or 6 divisions. Why not the whole
face of the tube?

Thanks Mark Anton
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm
European Boatanchors List: http://groups.yahoo.com/group/euro_ba_swap


Miroslav Pokorni
 

My guess is, just like analog meters, linearity between 1/3 and 2/3 is best.
The numbers are probably more generous for CRT, but there is something
there.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Mark Anton" <heightstv@hotmail.com>
To: <TekScopes@yahoogroups.com>
Sent: Monday, February 17, 2003 11:50 PM
Subject: [TekScopes] CRT question


I was wondering why on so many of these old scopes, that you are only able
to use so little of the screen, Like 4 or 6 divisions. Why not the whole
face of the tube?

Thanks Mark Anton.





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Craig Sawyers <c.sawyers@...>
 

My guess is, just like analog meters, linearity between 1/3 and
2/3 is best.
The numbers are probably more generous for CRT, but there is something
there.
I think that there is a bandwidth issue too. The 545A is the same vintage
as the 575 curve tracer. The 545A has a 10ns rise time for the mainframe
(35MHz) and has 4cm deflection. The 575 has 8cm. Now the CRT for the 575
also went in the 525 TV waveform processing 'scope, with a maximum bandwidth
of 5MHz.

So I suspect that in the 50's, there was a problem is getting high
deflection and bandwidth. It was also probably limited by the available
drive from wide band deflection amps at the time (the famous Tek distributed
amp).

Craig


Miroslav Pokorni
 

So I suspect that in the 50's, there was a problem is getting high
deflection and bandwidth. It was also probably limited by the available
drive from wide band deflection amps at the time (the famous Tek
distributed
amp).
As I read it in 'trivia ad nauseam', 'The famous distributed amp' was ironed
out over a dinner in Portland, Oregon, between visiting guest, Bill Hewlett
and his host Howard Vollum. It appears that both of them were considering
idea of such an amp and the occasion of a visit, which apparently were
frequent, brought about crystallization of design.

Regards

Miroslav Pokorni


Stan & Patricia Griffiths <w7ni@...>
 

The reason for the limited vertical deflection in the 540 series, for
example, is that the beam runs into the top and bottom deflection plates.
The scan is limited by the electron gun construction. Now if you want to
know why the gun is constructed this way, that's a little over my head, but
there have been a few good books written about CRT's that could probably
tell you . . .

Stan
w7ni@eaystreet.com

----- Original Message -----
From: "Mark Anton" <heightstv@hotmail.com>
To: <TekScopes@yahoogroups.com>
Sent: Monday, February 17, 2003 11:50 PM
Subject: [TekScopes] CRT question


I was wondering why on so many of these old scopes, that you are only able
to use so little of the screen, Like 4 or 6 divisions. Why not the whole
face of the tube?

Thanks Mark Anton.





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