What got me about the 485 - I was perusing the 4-series scopes on TekWiki - was that it was released before the 465/475s, but had the separate B-sweep trace. But the Wiki mentions that this feature was on the 465B. I'd forgotten about that, and was probably one of the reasons I preferred the 465B when working with them back in the Army. It made me realize that there's this weird mix-n-match of components and features between them. I realize the 485 is a different animal, and I suspect the separate B-sweep trace is implemented in different ways. The 485 is a full dual-trace system.
After getting into the guts of the 465 directly, and the 475 indirectly, and now the 485 just via the TekWiki description, why is the 465 so extensively implemented in discrete components and lesser bandwidth than the earlier 485 (350MHz) and concurrent 475 (200MHz)? Cost? Size? Weight? All of the above? Sure, I'm sure Tektronix made a market analysis and product development plan. And that these solutions addressed expected markets. Anyone have sales numbers? I bet the 465 cost lest, sold more, and probably made Tek more money.
One of the things that I've realized about being a circuit designer, vs. a system designer, is a lack of market awareness and knowledge. It's fine, I'm not a marketing type, and I don't come at the engineering profession as a product solutions person. I admire people who have the inclination and insight to find and implement market solutions. My interest lies closer to the physics of things. But I do find the product development decisions fascinating. Nobody really builds this stuff for fun. They build it to make money!
Steering it back to the original thread, why are the 465 and 475 chop blanking circuits so different, yet so similar? Seems a product development optimization that didn't happen? But I well know being on the inside of product development for the past 30 years, "you go to war with the army you have, not the one you'd like to have". The reality is likely a mix of planning, accident, and circumstance. It fascinates me to consider I was such a kid pedaling around Beaverton with my friends who's dads were engineers in Tektronix struggling with all these developments and the associated stresses and occupations. Appreciating now the realities of their experiences I was ignorant to as a kid, looking forward to unwrapping my presents under the tree. Some things just never change!