My Radio Shack DX-440 is a better radio.

Whaaa ?.... while an R-390A isn't for the "electronically challenged" it is
far from a maintenance problem once properly aligned. A healthy, properly
aligned R-390A should have sensitivity at 4 KHz of under .5 microvolts in
AM.... and they are remarkably stable. My R-390A is still in perfect tune
and it's been up and running 24/7 (except during storms) for 2 years now.
The R-390 series is NOT a difficult radio to work on... especially compared
to some solid state radios of late with their surface mount components.

What's the best source of information on getting the most out of these

First, there are a few R-390/R-390A gurus out there.

The "Grand Master" Rick Mish (Toledo,OH) http://www.dxing.com/r390/mish.htm

Chuck Ripple (Myock, NC) http://www.r390a.com

Walter Wilson (Augusta,GA) http://r-390a.us/

Excellent info available here too:
http://r-390a.net/
http://www.r-390a.net/Pearls/

The R-390 / R-390A receivers are arguablly one of the finest HF receivers
ever built. I have used them both as a hobbiest and professional.... along
with Racal, Harris, Watkins-Johnson, Cubic and other receivers. The
military went so far as to call several hundred out of mothballs in 1991/92
for use. What other military receiver can you name that has been
manufactured from 1951 through 1986 ? BTW.... check out the links on my web
page to my R-390A listening post..... "X2" all the way baby !

Mike
--
Michael Melland, W9WIS
Winneconne, WI USA
http://webpages.charter.net/w9wis