What are some smaller tubes that put off more light than most and are easy to come by? Preferably ones that use a pin base and socket, no top of the tube anode etc? I'd like to build an amp that will do about 150-200 watts out with 5 watts drive, and maybe up to 500 watts out with higher exciter power, that uses 4-6 tubes. If I did my math right that is in the 15dB gain range (add 3dB for every double in power - start with 5w, then 10, 20, 40, 80, 160w, right?). The primary goal is to have an amp for my Elecraft QRP rigs (KX3 and K2) that glows. I am not concerned with space and weight for the design, in fact I want to open up the specs for easy access, adjustment, and component selection (such as open air inductors). I am even thinking of building in a band pass filter section that works in TX and RX like what these are [https://www.arraysolutions.com/filters/w3nqn-filters-6-set?sort=p.price&order=DESC] but home brew and switchable from the control panel, either by relays or mechanical switches. I'm half way thinking open air tube construction (tubes free above the box) would be ideal, but the other side of me says that is too vulnerable so maybe a solid base box and a mesh screen for the top? I'd like to keep cooling to a minimum - maybe if anything use a muffin fan to waft air around the tubes. I'd just like to avoid forced-air cooling.