Alrighty, spurred on to acquire some nicer RF gens than my SG-165, I got a Panasonic VP-8131A. Actually I got a second parts unit as well.
I found the first one to be dead on acurate frequency wise and the amplitude seems to be fairly close but all I have to go on for that is my o-scope. This is a very easy to use front panel and I did not need to dig into the user manual to run it. You can arrow over to the digit you wish to modify when using the scroll wheels. The modulation readout has multiple modes depending on what function you have just selected to modify; kHz for FM deviation and % for AM modulation for example. I really like it!
I borrowed a spectrum analyzer from work to check the RF spectral purity and found it to be always better than -45dB on any harmonic at any frequency I dialed up. The spec varies for different frequency bands but the best ranges call for better than -40dB so this unit is fine.
The parts unit was an interesting deal. I saw an ad on eBay with a stock photo and asked for real pictures - this was before buying the one I got from another source. I got back a picture of a unit with a bashed in front and the seller mentioned that he tested it and found it "dead", would I be interested in an as-is deal. Of course! So after a bit we came to terms and I got it thinking parts unit. Here it is as I got it.
At least the back was intact although I later found a trashed BNC on RF Out #2. I had also cleaned off some melted black goo from the inner rubber feet having melted / decomposed on the top inner cover. I brought it up on the variac and found a somewhat incorrect display. Enough OK that I thought the micro was running.
I took off the top inner cover to see how that looked inside. It looked fine.
The I thought I'd see how badly the front pc board (for the display and buttons) was messed up so I unscrewed the assembly and pulled it out and the board away from the bracket. I didn't see any damage other than it was kind of tweaked because the aluminum bracket was so bent up. When I fired it up it worked fine!
After some putzing around I got the bracket pretty straight and gave it a light sanding.
I peeled off the front sticker that says "VP-8131A" and the original labelling was "VP-8121A". Hmmmm, I'll have to go find out what the difference is. It could be that it was upgraded later to an 8131. That would be the optimistic way to look at things!
I haven't reassembled it, I want to measure it all out and get it drawn up so I can design a new front laminate (sticker). We make our own at work for our products so I have a shot at talking the engineer in charge of that area into helping me out. I'm thinking of doing it in black with white lettering as I have to repair the front plastic bezel and paint it. Black is easy to do! I'll post that if it happens.