Ed, Brad
I didn't think about the plastic in front of the CRT. Removing it makes the
7934 storage CRT glow nicely. Removing it from the 577/D1 makes the phosphor
glow faintly in PURPLE! I didn't expect that. The characteristic curves show
up in green on this curve tracer so is this CRT coated with two or more
phosphors?
This is getting complicated. There are short persistence phosphors and long
persistence phosphors responding on some of these CRTs.
It would be good to hear from a Tek Phosphor expert about all this.
But maybe others will give it a try with other color LEDs on whatever scope
they have since it is so easy to do.
Dennis
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-----Original Message-----
From: Ed Breya, Tuesday, January 24, 2012 10:23 AM
Yes, UV LEDs are the way to go. The old school cameras we discussed had
plenty of UV from actual UV lamps, or the high UV content from a xenon
flash. The other variable is the UV loss in the plastic layers in front of
the CRT. UV LEDs should be readily available. I bought some in the form of
small keychain flashlights from a surplus store years ago - there should be
even better and cheaper ones around now.
The intense blue LED wavelengths work fine for the modern "white" LED
phosphors, but apparently not so much for CRT ones.
Ed
-----Original Message-----
From: Brad Thompson, Tuesday, January 24, 2012 9:56 AM
<snip>
Hello, Dennis--
Have you tried using ultraviolet-emitting LEDs? IIRC, one of the --HP--
oscilloscope cameras used a UV emitting lamp to light up the screen's
phosphor and show the graticule.
73--
Brad AA1IP
