[AMRadio] 78 records and aluminum

Nigel Holmes Holmes.Nigel at abc.net.au
Thu Jan 21 23:12:57 EST 2010

They're "acetate" discs, 16" OD for a 15 minute transcription (33 1/3rpm) in broadcast service, (12" & less was used for domestic recordings). Some went up to 17.5" OD

Recordings were not great at less than 6" diameter hence the big diameters. 

Used a cellulose lacquer on the aluminium platter which produced swarf that was the basis for truly excellent "bombs" when packed into small bags & ignited with various fuse wires, usually under unsuspecting colleagues' desks. 

Every heavy metal '50's AM broadcast tx in amateur service should have a Presto or Beardsley recording lathe for log-keeping.

Another BA angle: Here's  http://cgb-1.com/pod/20090929.jpg a Jap seaman on a WWII navy ship preparing to record enemy CW for subsequent authentication of the fist.

Nige  VK3DZ

On Thu, Jan 21, 2010 at 7:10 AM, CL in NC <mjcal77 at yahoo.com> wrote:

> I have several test circuits I salvaged before they hit the dumpster.  These were built in the late 50's, early 60's.  They were in homebuilt Bud type miniboxes, and the constructor, Fritz, W4NTO said the aluminum came from old records.  They melted the plastic off the disk and a shiny aluminum platter of the perfect minibox thickness remained. The aluminum was high qualtiy and even to this day, the inside of the chassis are as bright as chrome, not one hint of corrosion.  The outsides were painted.
> So that old cracked and scatched Caruso 78 might have a gold mine of aluminum under its useless surface.
> Charlie, W4MEC in NC
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