[BC] RF gasketing or not on old CCA

[Dana Puopolo]

On an old 20, I drilled holes for screws and nuts and mounted them to the
cavity beside the Dzus holes. You need to also countersink the
nuts-fortunately the aluminum used in the cavity is thick enough to do this.
Put a screw every 2-3 inches all around. Then (of course) you drill mating
holes in the cover, and  nut the cover on. I used 1/4-20 screws.  This worked
fine on the 20-even better then the older fasteners! I also made a tube puller
that used a plate that fit atop the chimney and had a long threaded rod and a
chain that attached to the tube handles. It sure made changing a tub easier!

------ Original Message ------
Received: Mon, 15 Oct 2007 08:36:37 PM EDT
From: "Jerry Mathis" <thebeaver32 at gmail.com>
To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
Subject: [BC] RF gasketing or not on old CCA

I've got an old CCA 25 KW FM transmitter in standby service. When they built
these, they didn't use an RF gasket or spring contacts on the RF cavity
door, they just had bare metal-to-metal contact with the standard Dzus
fasteners. The door and its mating service are now heavily pitted, and most
of the Dzus fasteners around the tube cavity section are burnt off. Needless
to say, the transmitter is not stable operating this way.

Has anyone had success trying to repair a situation like this? What did you
do? I'm thinking of adding an RF gasket and getting new Dzus fasteners. BTW,
where can you get these, inlcuding the part that mounts on the cabinet? Do
they come in sizes? If so, how do you pick what size you need? And what type
of gasket would you recommend? I've seen at least three different types. I'm
considering the kind that has wire woven into a fabric. It looks kind of
like Scotchbrite, or a felt pad.

The transmitter is still very functional outside of this problem, so I want
to fix this if possible.

-- 
Jerry Mathis
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