radar history

William Donzelli wdonzelli at gmail.com
Sun Mar 4 16:28:09 CST 2018

> A very interesting story in this radar history is how the Dutch managed to
> rescue the EF50 tube, essential for these early radar receivers, to England
> just hours before the Germans invaded holland.

This is generally a good article, but has a major flaw or two.

One, it describes acorn tubes as costly and difficult to build. This
was certainly true in Britain and Europe - for some reason the
overseas makers had a very difficult time getting acorns to work (and
last) properly. This was not the case for RCA - there were large
numbers in service by 1939. RCA must have kept the "secret" to making
acorns tight to their chest.

Two, it poorly describes (almost not at all, actually) the Sylvania
loctal that came before the EF50. Most of what makes an EF50 can be
found in the loctal series. US radars generally did not use loctals
(some IFF transponders did - a related technology), but by 1940, the
loctal was pretty obsolete and the 7 pin miniature banging on the


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