[Collins] re: R-388 MC drum

[Dr. Gerald N. Johnson]

On Sat, 2008-07-12 at 21:55 -0700, wli wrote:
> I am refurbishing my new treasure: a 1954 R-388/URR. The MC drum is severely yellowed on Band 1 where it was evidently left in repeated sunlight. The rest of the drum is intact, and only mildy yellowed. Is there anything else other than dilute sodium hydroxide that will remove the dark yellow band wihtout distubing the numerals?
> 
I'd think that sodium hydroxide in any solution strength would not
bleach the yellow, but might act as a paint stripper to remove the
numbers completely. Hydrogen peroxide is a mild bleach and might have
more of an effect on the yellow, but I expect the numbers to fade too.

> Afterwards, I was planning to cover the entire drum face with clear acrylic in order to preserve it. Will that damage the numerals? 
> 
Depends on the paint the numbers were put on with. If the paint or decal
(paint on transfer film) that's dissolved by the solvent in the clear
acrylic the numbers may wrinkle, or move or smear. The clear acrylic
won't protect the numbers from fading or yellowing, it may yellow itself
with continued UV exposure.

> Thanks
> 
> W. Li 
> 
> 
NOS drums as well as replacements may be available from more than one
source.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer