I'll post this reply (from another thread) here as well, since this thread is dedicated to the 79-290.
There is a VR in there for the S meter as well as for Tx side of it, but I can't remember which one it is exactly. Justin might better know which pot is which. Besides, turning it down just for the sake of local 30db signals will de-accurize it for the weaker ones. There's also a IF xformer to better tune for the WX band on your antenna setup, that way the coarse/fine tune controls will center nicely and allow for max. reception. I have the exact VRs documented in my file of papers, but since my recent move, things are sort of not in order yet and they are packed away somewhere! If I find those documents, I'll be sure to post any corrections here... otherwise I could be talkin' out of my arse!
Please don't hold me to this (and you might want to index mark a VR before twiddling it), but off the top of my head I
"think" the following VRs may be:
red circle: tx & rx trimpots
yellow circle: WX I.F. xformer
magenta circle: modulation trimpot
orange circle: rf bias trimpots