[Milsurplus] ARC-27/55 radios

[Don Davis]

Other reason it was pressurized was for high altitiude use where arc-over
due to small partial pressure of air would cause Paschen break-down.  This
is effect where arc distance is minimal at some point between sea level and
absolute vacuum.  U.S. aerospace high voltage equipment goes to great
lengths to prevent this.  Russians were brute-force and mounted their
hi-voltage stuff in pressurized enclosures.  AND - it did a great job
improving cooling as well, especially when they added electronic solvent
vapor to the box.  No convection cooling in space....

73s

Don  AD6PB

Clete says:

Trivia:  One reason the
> ARC-27 was pressurized was to enhance the heat transfer
> and cooling.  The blower fan, which was replaced with
> a feed from a cool air duct in GCA's and some RAPCON's,
> circulated the air through a complicated duct about
> 3/4 inch wide that went all around the inner chamber
> which was air tight.