[ARC5] Front panel widows

[Michael Bittner]

All of my ARC-5 transmitter windows have black index marks and lettering on 
clear plastic with a white background in the the lower part of the window 
that makes the black lettering stand out.  All are in excellent condition 
and show no signs of shrinkage.  These could be duplicated on acetate sheet 
by reverse printing black on the back and then masking and painting the 
lower part of the back with white paint.  Or, reverse the process by first 
painting and then printing on the front.  You'll need artwork stored as a 
file to start so that you can print black on an acetate sheet or decal. If 
you print on the back, Microsoft "Paint" is one program that allows you to 
reverse artwork including printed material.

I have one ATA and one SCR-274 transmitter.  Both have the stamped white 
index marks and numbers on the fronts of their windows that have badly 
shrunk in the width direction with the white paint flaking out.  I don't see 
any way to duplicate these without some means of printing white.

I'm wondering if different materials were used for the ARC-5s than the ATA 
and SCR-274 based on the excellent shape of the ARC-5s as compared to the 
otthers.  Maybe they were just exposed to different conditions, or maybe 
they are not all cellulose acetate?

In following this this thread, I've been confused by use of the term Command 
Transmitters and ARC-5 as a generic terms including ATA and SCR-274 
transmitters.  In this case, there's a difference.

Mike, W6MAB





























----- Original Message ----- 
From: "Brian" <brianclarke01 at optusnet.com.au>
To: <arc5 at mailman.qth.net>
Sent: Friday, February 03, 2017 5:45 PM
Subject: Re: [ARC5] Front panel widows


> The original window material in the Command transmitters and BC-221 family 
> was nitro-cellulose acetate - the basis for early cine film. The original 
> solvent gradually evaporates, leading to physical distortion and 
> coloration. You could smell the solvent in the early cinema projection 
> rooms. The degradation is not reversible. The observation that a solution 
> was to buy up old stock transmitters to scavenge their windows will not 
> beat the natural chemical and physical degradation.
>
> The better solutions emerging from this discussion are the use of Perspex, 
> Lexan, other clear cyano-acrylates and polycarbonates, though even these 
> will change shape over time. Plenty of this material is used for 'gels' 
> over follow spots for stage shows - and so becomes a cheap source of our 
> raw material. Think how sexy your transmitters would look with yellow, 
> green, blue and red windows!
>
> The scales and numbering on the Command transmitters varied between 
> manufacturers and most definitely with operational frequency range; on the 
> lower frequency models, the markings were closer spaced. So, the 
> possibility of making 'one size fits all' is a forlorn hope.
>
> My solution was to photocopy an engineering mm scale onto clear plastic 
> and cut to fit. Cheap and cheerful. In the old days of Drawing and Design, 
> scales with all sorts of spacings and numberings were available.
>
> 73 de Brian, VK2GCE.
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