Re: Update on 2465

Chuck Harris
 

A minor nit: The 2465 family CRT does *not* have an
expansion mesh lens!

It uses a "box" lens based on a quadrapole design.

The quadrapole lens eliminates most of the distortion
and all of the flaring exhibited by the expansion mesh,
to the point where the beam size after expansion is almost
exactly the same as it would be with a longer CRT that
has no lens.

The 2465 family has a much shorter (2 inches) CRT with
a much larger (36% more area) screen than does the 454A.

If you could expand the 454A's screen the 36% from
8cm x 6.4ch to the 2465's 10cm x 8cm, the 454's dot
would be much larger than the 2465's.

The reason most people think the 2465 has a larger,
fuzzier beam, is because the beam incorporates all of
the extra noise due to its 400MHz deflection amplifier
bandwidth.

Reduce the bandwidth to 20MHz, and the beam size is
very compact.

-Chuck Harris

Sigurður Ásgeirsson siggi@... [TekScopes] wrote:

On Wed, 4 Jan 2017 at 06:45 tatumj1@... [TekScopes] <
TekScopes@...> wrote:
Also, you shouldn't expect the 2465 to match your 454A for trace clarity or
dot size, as the 2465's CRT has an expansion mesh.

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