[Boatanchors] copper screen

w9gt at comcast.net w9gt at comcast.net
Thu Mar 22 07:07:42 EST 2007


 Lots of old HF broadcast equipment with windows for viewing the
> tubes included a layer of copper screen wire (like window screen)
> attached to the glass, with the screen electrically bonded to the metal
> case around the perimeter of the window.

My 1946 BC transmitter has only glass between the tubes and the free
world, but my largest amateur transmitter from '52/'53 has a very nice
screen between the 4-250s and glass, chrome plated but painted a flat
black color so you have to look close to see it. Earlier models like
the Collins 30K have no screen behind the glass either, so it would
appear to have come along as TV use became more prevalent with the
accompanying TVI. Cable and satellite TV have probably negated a lot
of the issues.

~ Todd,  KA1KAQ

My Collins 30K-4 has copper screen on the inside of the glass....probably was added by previous owner.  In the 50's-60's time frame there was a great concern about TVI and it is not uncommon to find such shielding added on insides of rigs over vent louvers and other openings as well as viewing windows.

Anyone know where you can purchase copper screen?  It used to be commonly available at the local hardware, but haven't seen any for years.

73,  Jack, W9GT


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