So purchased this on eBay out of curiosity. Still can't find a single mention of a Model 4009 Function Generator by B+K. Anyone know where this is from? Legit or well made forgery? It's accurate beyond my measuring capabilities, but there are some things about it that shout out fake. Namely, the unlabeled (doesn't seem to do anything either) knob on the front panel and the fact that there isn't a single mention of such a model anywhere on the internet, apart from the actual eBay listing for this exact one! I have enough time to do a full tear down on it, but I did pop it open real quick just to take a quick pic for the EEV! Anyway, curious little device. I can post more pics and such later if you guys want, but better get back to work!