These are nice receivers. I spent nearly 4 years behind a bank of at least 4 and sometimes 6 of them. If you are not technically inclined, I would not power the unit up to test it. Although it is not as old as the pre-WWII Hallicrafters I like to work on, it is always best to power up an old tube receiver slowly with a variac (variable voltage source)if it has not been energized for a long time. I have seen many old receivers with blown RF coils caused by a short circuit after someone powered them up to see if the radio would play.
Oh my, you are lucky indeed.
The R390A is a
wonderful receiver
(photo) and is, in fact, incredibly sensitive with a -143db noise floor which is close to the galactic noise limit.
The first one that I ever used was at NASA back during the ancient
Apollo days when they were used for long haul HF/shortwave work in the event that satellite comm went down.
Many experts consider the R390A to be the finest HF receiver ever built. They were, in fact, designed for the US
Spook Community and were classified TOP SECRET during the Cold War.
Whatever you do - don't hurt that radio. If it has not been powered up in a long time, I recommend that you find someone capable of working on it -- it is
not a simple beast to align etc.
I have most of the operating and service manuals in electronic form (I have had my own R390A since 1997) and can forward them to you if you want - Send a private msg.
