I'm no expert, but friends call me Tube Man for a reason, I used to be a walking tube manual. It's been a while, so having lost my tube manuals in transit I rely on scanned pages on the Internet. Yep, that's where to look for Everything You Ever Wanted To know About Tubes But Were Afraid To Ask. https://duckduckgo.com/?t=ffsb&q=4-4...cations&ia=web (Just my twist on a very funny 1972 Woody Allen movie.)

You're headed in the right direction, Johnson skimped on everything since the original Viking transmitter, IMO the only good thing besides the matching VFO they ever made. I see so many shortcomings in that amp that I would do a major rebuild to bring it up to my standards beginning with those cheesy 500pF 15KV B&W TV doorknob caps and that pathetic fan that just have to go. There are proper .001uF doorknob caps available, (Johnson paralleled 2 to make .001uF) and I'd give particular attention to the plate bypass cap on the cold side of the RF choke, if that's another TV cap I'd replace it with a .01uF doorknob.

Pressurizing the underside of the chassis with a squirrel cage blower made for the purpose will keep the critical base seals temperature down. If you can fit recommended ceramic sockets with mating glass chimneys for the fire bottles do it, but I have my doubts, they look too close together and too close to the cabinet. At least there are much needed finned plate caps on them, anode seals are also critical.

Oh BTW, plate and screen voltage under load is what you really need to know, but you won't until you fire it up into a dummy load. 1A is WAY too much under ANY circumstances, as voltage goes up current goes down (V X I = W). For 2 tubes at 3500V plate, 500V screen, and -170V grid you get 500mA DC plate current. Back in the day 1KW DC input was FCC maximum, typical RF output is 500W with a well designed Class AB1 amp. I hope you have one that can handle a killerwatt, your fellow hams will appreciate it.

Since you are almost there, whatever you do don't get anxious to put it on the air and hurry to completion, remember haste makes waste and GOOD LUCK. As a boat anchor man who unfortunately had to downsize before turning to paper I like what you're doing, keeping vintage technology ALIVE. One last comment that will save you from a killer electric bill, unless you need to overcome an AM Gangsta's high noise floor more than 100W is wasted. Operating K2PG when I lived in West Creek, NJ I was Phil's DX magnet using his Drake TR-4. The first trick in the book is patience, tune around listening for his CQ and jump on it before the dog pile finds him. By the time the DX is posted on an Internet reflector there is a heavy dog pile already in progress, ignore the reflectors. Once that happens all is lost unless he's working split and you have dual VFO capability. Find the guy he's in QSO with, that's your TX frequency, as he signs step on him, it's called coat tailing. (Nobody will hear such a dastardly act, hi.) Don't ever try to be top dog in a dog pile even if you have your killerwatt at the ready, you'll NEVER break the California Kilowatt Curtain. On 20M I tried with a Collins 30S1 into a 3EL tribander up 60ft (optimum for that band) and failed miserably. That one time taught me not to waste electricity. ('->) If it makes you feel better the left coasters have the New York Kilowatt Curtain to contend with... heh, heh, heh.