[Boatanchors] copper screen

[mikea]

On Thu, Mar 22, 2007 at 12:07:42PM +0000, w9gt at comcast.net wrote:
> > >  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.

>From time to time, I've seen notices on one or more of the Glowbugs,
Homebrew, and Boatanchor lists that silver mesh, silver-plated copper
mesh, nickel mesh, and copper mesh are available. The last one was
Wed., 16 August 2006:

: From: Ron <w8ron at stratos.net>
: To: boatanchors at mailman.qth.net,
:    ForSale-Swap List <ForSale-Swap at mailman.qth.net>
: Subject: [Boatanchors] Silver Plated Expanded Mesh
: 
: I have 12" x 12" sheets of silver plated copper mesh screen and will 
: sell 10 for $22 including postage.
: The mesh is about the thickness and hole size of screen material that 
: you would use for your windows.  The base material is copper then there 
: is a flash plate of nickel as silver can't plate to copper directly. 
: Then there is a good plate of silver as the material was to be immersed 
: in caustic KOH solution.  Any holes would lead to the KOH attacking the 
: copper base.
: This is an expanded mesh and not woven.
: It is clean flat and undistorted and would make excellent material for 
: grounding and shielding.
: 
: 
: 
: I also have nickel and plain copper mesh 12 inches wide on a roll.
: ---
: Ron

and 

: Date: Wed, 16 Aug 2006 14:22:27 -0400
: From: Ron <w8ron at stratos.net>
: To: ForSale-Swap at mailman.qth.net, boatanchors at mailman.qth.net,
:    AMPS <Amps at contesting.com>
: Subject: [Boatanchors] Pure Silver mesh
: 
: I have available a few sheets of 99.999% pure Silver expanded mesh.
: 
: Each sheet is about 10  x 8 inches and weight is 44 grams or 1.41Oz troy.
: THe mesh is .008" thick with expanded and flattened diamond shaped holes 
: .045 x .100 " center to center on the diamond shapes.
: 
: Picture is available on the net at 
: http://my.stratos.net/~w8ron/SilverMesh.jpg
: $34 per sheet plus shipping.

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin