I appreciate your advice, and I read your similar thoughts at http://www.eham.net/ehamforum/smf/index.php/topic,95048.msg739244.html#msg739244
Right or wrong, in my legal limit amp I have an AGC2 fuse and two 10 ohm resistors, all in series. In both amps, I blew several AGC fuses not long after I installed new tubes. In each case, the dim blue flash (when the fuse blew) was of very short duration.
I am fully aware of fuse open time vs. current curves. My thinking --admittedly not based on any math or tests-- was that the 10 ohm resistor would limit the current so that the fuse wouldn't arc or explode. (In other words, the series resistor effectively increases the voltage rating of the type AGC fuses by limiting the arc current [preventing the fuse from developing a sustained arc].)
I've also heard stories of cheap resistors exploding, whether or not the fuse was there. I did have one resistor (one of those cheap white square ones) open when the fuse blew in my homebrew 2x833C amp, and so I have some brown Ohmite vitreous enamel resistors here now in case that happens again.
I know a guy who built an amplifier, who just has a large high voltage fuse in series with his power supply and his 3-500Zs. I could never convince him to add a 20 ohm resistor. His reasoning was that he's blown more than one HV fuse with no other damage.
If I were using tubes with delicate grids, I sure wouldn't have the fuse in there without some means of disabling the drive when it blew. :-)
Maybe I ought to jumper the fuses. But having them there makes me feel better.
EDIT: I'll look at the 3AB.
I don't think a fuse, or the suppressors on that web page, are such good ideas. The rest looks pretty good.
Let's not kid ourselves and other people about fuses. When an AGC style fuse opens at high voltage, which already takes more time than people think at low voltages, it can sustain current through arcing plasma for seconds.
The only reliable or significant damage reduction comes from the resistor, so the focus should be on it.
I'd just add the right resistor, and not worry about a nuisance part that doesn't protect and only tells us the system had a fault.
The closest cheap fuse that affords some protection is a 3AB type. http://www.littelfuse.com/products/fuses/cartridge-fuses/~/media/electronics/datasheets/fuses/littelfuse_fuse_508_datasheet.pdf.pdf
If people are just sticking an auto-glass fuse in there, they are doing nothing to reduce surge duration time. The fuse is gone after the arc stops and the plasma goes away. During the fault, the fuse is just a low voltage drop plasma ball of vaporized metal and superheated gasses. http://www.littelfuse.com/~/media/electronics/datasheets/fuses/littelfuse_fuse_312_318_datasheet.pdf.pdf
Fuses stop fires, they don't protect things during a HV fault.