The Ware for June 2021 is an Amplifier Research AR200L 200W linear power amp. This is the last (for now at least) of the very fine set of wares that Don Straney had contributed. Thanks, Don! They helped get me through the pandemic, until I can travel the world again and stumble across new wares. Unfortunately, the delta variant means any hope of travel in the near term is probably off the table. But! I still have a screw driver, so I’ll be scouring my place for interesting things to photograph and share.
I’ll pick Phantom Deadline as the winner for last month’s competition, congrats and email me for your prize! I found the comment thread to be very interesting to read; I’m a decade too young to have learned how to design with vacuum tubes in college, and I never picked up tube design later on. For me, at least, I had no idea what I was staring at when I saw the ware initially. So, I appreciated the discussion of vacuum tube RF design tricks. Thanks to everyone who commented, for teaching me new things!
About the “what is it for” and the “why so many parallel tubes instead of one large tube” discussions:
It was being used for MR applications (before getting trashed) although it seems pretty general-purpose; the rated frequency range is 1-200 Mhz @ 200W continuous or 400W pulsed. The “plate impedance transformation” explanation makes the most sense to me for going massively parallel; while extremely wideband multi-stage (or just very carefully-designed) 1:1 or small-ratio baluns for example are doable, the idea of having to build a large-turns-ratio transformer that works well all the way from 1 Mhz to 200 Mhz (and can take 400W) is kind of terrifying.