Beam-penetration color CRT, Tektronix DAS 912x (was Re: Nice LAB11 brochure.)

Eric Smith spacewar at
Fri May 20 01:18:45 CDT 2016

On May 8, 2016 9:33 PM, "Eric Smith" <spacewar at> wrote
about the CRT of the color monitor of some models of the Tektronix
DAS 9100 logic analyzer:
> It is custom, and it is tri-color (red, green, yellow), but it's a
> beam penetration CRT that is not a modified version of any normal
> color CRT. There is no shadow mask, and it can only draw one color per
> field, like the 1951 CBS field-sequential color television, though
> that was done with a color wheel while this is done by modulating the
> anode voltage (and possibly the deflection drive as well).

On Mon, May 9, 2016 at 7:45 AM, Pete Lancashire <pete at> wrote:
> I must be thinking of a different  model.

Now that I've looked at volume 1 of the DAS 9100 service manual, I
believe my information was incorrect. Volume 1 is scant on details of
the color monitor, but it does say that the anode voltage is 21kV. If
it was a beam-penetration CRT, it would have to be switched between
different voltages for red and green.  (And yellow, if that was
generated with its own phosphor layer rather than as two passes with
red and green.)

The color monitor is manufactured by Tektronix using a CRT also
manufactured by Tektronix. The monochrome version uses a monitor OEM'd
from Motorola.

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