For giggles I added a couple of photos of my 2467's geometry "problems" to
the album (
/g/TekScopes/album?id=86473). Note that this
was the first (and only) time I've been through the calibration of a 2467,
so I'm by no means an expert. From the photos I uploaded, I'd say the
distortion on mine looks like vanilla pincushion distortion - it seems
likely it would be possible to do a better job, or adjust this out
altogether.
On Sun, Mar 10, 2019 at 11:25 AM Chuck Harris <cfharris@...> wrote:
I settled the grid issue, to my satisfaction, by hooking a
1 division square wave to the CH1, 2, and 3 inputs, turning
on the CH1-4 display, and triggering on AC mains.
I adjusted the vertical positions so that the pair of lines
visible for CH1-3 covered the lower graticule lines, and the
baseline trace covered the upper graticule line... leaving
out the top most, and the bottom most graticule lines, as
tek doesn't seem to think them relevant.
I then adjusted the time cursors to the first and last
graticule line, and the full picture of the distortion became
visible.
Lets number our horizontal graticule lines as follows:
outer most top line we ignore.
1-4 where 4 is the center line.
4-7 where 4 is again the center line.
outer most bottom line we ignore.
My CRT is almost perfect on line 1, but grows more and more
bowed to a peak at line 3, where it grows less and less
bowed to a straight line at line 5, After line 5 it starts
to bow downwards, to line 7 where it is bowed a little.
As to physical damage:
The 2467 CRT is built like a brick outhouse, except in 4 elements.
These elements are fringe shields for the vertical and horizontal
deflection plates, and are basically V shaped channels that are
positioned at the sides of each plate pair... in other words,
they cover the space between the left and right horizontal plates,
and the up and down vertical plates.
These shields are connected to anode1, and can be seen on the CRT
schematic as dashed lines.
Anyway, these are longish structure that are only fixed on one
end.
Everything else in the CRT is fused to the heavy glass rods that
define the positions and structures of the CRT.
-Chuck Harris
Harvey White wrote:
On Sat, 9 Mar 2019 21:38:36 -0500, you wrote:
Two frame calibration standardizers will work, I think, certainly one
will give you horizontal lines. I seem to remember using two of them
and getting a grid. Different scan rates, though.
Harvey
Hi Rolynn,
There is no setting of the geometry that will allow
my 2467B to have a straight horizontal trace in the
center of the screen. It either bows up a little bit,
or it bows up a lot. The switch between bowing up and
bowing down is about 2 divisions from the bottom of
the CRT.
