Love this comment on the 390A from Wikipedia:
The R-390A was deployed to most branches of the US military and remained in general use through the 1980s. The last major update to its documentation was in 1984. As the military procured newer receivers, many R-390As were released to surplus while others were destroyed. Some receivers were retained by the services, however, when they found that the R-390A's vacuum tube circuitry could easily survive an electromagnetic pulse. There are reports, possibly apocryphal, that R-390A receivers are still in use aboard U.S. Navy submarines since the receiver can withstand the strong radio frequency fields found aboard ship.
Many of the R-390As that exist today are in the hands of vintage amateur radio collectors and amateur radio operators who contend that few modern solid state communications receivers can equal its performance. There is a wealth of information, both printed and electronic, devoted to R-390A restoration and maintenance, as the R-390A is widely considered an example of the best of vacuum tube technology.
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The most improper job of any man, even saints, is bossing other men. Not one in a million is fit for it, and least of all those who seek the opportunity.. J.R.R. Tolkien
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