B+ protection resistor??

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LA6TPA:
I think at our energy levels, 10 ohms glitch resistor is good value. Resistor wattage has to be rated according to your maximum mean current (P=RxI²).
Fuses are a bad idea and will not work unless they are rated for the voltage they have to isolate after they break.

73
Geir

k4kyv:
I never used a series resistor, but I do have a fast-acting overload relay circuit in each one of my transmitters.  I would have saved myself a tremendous amount of grief (far beyond the mere transmitter - a long story) if I hadn't build my first high power transmitter without one.

KM1H:
Back in my custom 1 and 2 hole 4-1000A building days of the 70's and 80's I always used a HV fuse and a 25/50 glitch resistor. Fuses were plentiful and cheap on the surplus market and since the tubes were always pulls it prevented other damage from a long sitting gassy one. No PS chokes were used and the C was never over about 12uF of series parallel 3-4KV oil filled with 5-6KV of DC. A bit more C for those who wanted 4000-4500V and I bought 200uf/450V SB-220 caps in bulk. Never had the nerve to series them up for 5-6KV!

I learned about the glitch resistor at National which had a 10/10 in the 1963 released NCL-2000. That might have been a first for a commercial ham amp?? It also had a plate overload relay set at 1.2A and the only time that would trip is when the poorly supported 8122 screen leaned into the anode. The tube was toast but nothing else got damaged but a 100 Ohm 1/2W carbon screen "fuse". By late 65 RCA redesigned the tube with ceramic screen spacer supports.

N4LTA:
I have always theorized that the inductance of the wirewound resistor would limit the di/dt as does the resistance but have never really looked at the rise time of the current pulse is a flashover. It can't hurt but the resistor voltage may go very high.

I have used a 5 KV fuse also but they are large (approx 6" long )

Opcom:
I use a #30 wire as suggested by a wise man, but what about the 10 Ohm 10W WW resistor? Will it explode? 3500V, 24uF output cap - -maybe it is going to get real hot before the fuse blows.

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