Graticale - SB610

[Mike Morris]

Sorry about just now replying to a 6-day old message, but I just
now read it...
I am not familiar with the '610 graticule but if it is anything
like an old DuMont scope I worked on, the lines are scribed into
the plastic, then filled with white <something> - paint, maybe...

Heath - at least on the '610 - may have gone the cheap way and
used silk-screening on unscribed plastic.  If yours is scribed,
then chalk rubbed into the groves should make it white again.

Another method:
Years ago a friend of mine acquired an older tube-type Tek
scope - a 1960s model 513 I think - from a hamfest but with
the graticule missing.  We found a dupe scope at a surplus
store and "rented" the graticule for a few hours, took it
over to a copy store, and had them make copies on both paper
and on clear plastic - an overhead projector transparency.
Be careful, some public machines drift out of optical adjustment
and actually do a 3-5% reduction when it is set to 100%, so
you may have to hand-pick the proper machine to make an
exactly sized copy.

Note that if you have a white-on-clear graticule then a black-
lines-on clear film transparency is not going to be stock, but
if nothing else it's a good temporary replacement.

To do it right, take the loaner graticule to a photographer
and have him make a "contact print" onto black-and-white film
(producing a negative image), then a second contact print from
that one to get a positive image.

Then we took the original graticule to a plastics place - there's
a chain here in L.A. called Paragon plastics that sells raw
plastic of many types and sizes.  We got two half-thickness pieces
of the proper material, then returned the original graticule.
In the garage we sandwiched the transparency between the plastic
pieces, then used 4 C-clamps to hold them between two pieces of wood
buffered with felt, like so:

use a monospaced font to see this:

paper copy ----> ----------  <glued with rubber cement to the wood
wood       ----> ==========
felt       ----> ----------
plastic    ----> ==========  < glued together
transparency --> ----------  <
plastic    ----> ==========  <
felt       ----> ----------
wood       ----> ==========

We glued the new graticule together with model airplane glue -
we ran a bead around the edge of the sandwich and let it sit
overnight.  Be careful with the glue, don't use too much or
let it drip - it is a solvent and turns the clear plastic
milky white.

Using the paper copy as a guide, we used a drill press to drill
all the proper holes by just running the drill through the
entire stack.
Bingo - one replacement graticule.  Total cost about $5 (ten years
ago).

Mike Morris  WA6ILQ



At 09:09 PM 04/13/99 -0400, you wrote:
>Through the help of many on this reflector, I've been able to get a
>basket-case SB-610 up and running well. The remaining problem is the
>sorry state of the graticale -- that green plastic that goes in front of
>the CRT with the white lines on it.  Does anyone have one they can
>spare??  Or any ideas on how to refurbish mine??  The white lines are
>about gone even though the plastic is usable.
>
>Thanks
>73, Stu - W6CUX
>Winnetka, CA
>ARRL Life Member
>
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