[R-390] R-391

[edw488 at earthlink.net]

I picked up a R-391 today at a radio auction, and have a few questions for the group. The radio is a Collins and looks fairly clean and unworn, came with original meters, covers, knobs, etc, just really dusty... and it does work quite fine, a pleasant surprise!

First, what are the weak points of the R-391, besides the hot running 6082's? Aren't there some high watt resistors that get cooked?

Second, the panel tag is kind of odd looking compared to other R-390 and 391 tags and carries a serial number of PP4. My guess is that it means "pre-production 4", anyone know for sure?

Thank in advance guys, from Ed, N3LHB.