RadioBanter - View Single Post

December 28th 05, 09:26 PM posted to rec.radio.amateur.boatanchors

In article ,
(Steven Swift) wrote:

According to my DuMont handbook of CRTs, a yellow filter can be
used with a P7 phosphor CRT to allow viewing of the long decay
part without being "blinded" by the bright blue trace. I've searched
Ebay, Sphere Research and other sites looking for these.

Anyone have one good for a 3" round CRT or know of a good substitute
material (perhaps from a hobby store)?

The trusty Wratten 85B (I think) filter used to convert daylight to
tungsten-equivalent lighting for photograpic work is probably about
right. (You want the lighting grade, not the camera filter grade,
as it's a lot cheaper.) Or any suitable stage lighting 'gel' - for
best results, get one that is an exact match for the afterglow, as
that will give you the brightest trace while still knocking down
the blue component.

Tinted Perspex (Plexiglas) may also be worth a try, or even the brown
cellophane you get in some chocolate boxes, sandwiched between two
sheets of clear plastic of glass. (I won't suggest rolling your
own filters out of gelatine and food colouring.... Yet!)

Hope this is some help,

Chris.

--
"It's 106 light-years to Chicago, we've got a full chamber of anti-matter,
a half a pack of cigarettes, it's dark, and we're wearing visors."
"Engage." -- Paul Tomblin in asr