I used 1ohm/1watt comps. For hi power linyears I put 2 in parallel.
So did Dentron
I disagree completely.
The idea is to rightsize the glitch resistor so it will open without delay....in fact, I like mine right on the hairy edge of talking it open.
I also think a single wirewound resistor such as a tub, sand, power resistor or watever you want to call it....is the way to go because it opens quickly. Multiple paralleled resistors would likely take longer because of the way the current would divide.
Also, in post 25, he does not mention the diode string or the transformer secondary and perhaps choke that could be damaged if the glitch resisistor is slow to open.
I think LA6TPA has it right. That's how I size em'.
Disagree all you want but youre still wrong.
The purpose of the resistor is to limit fault
current to a safe level until a fuse opens and survive. An awful lot of nasties can happen if you really think a little resistor will not induce a plasma arc. How many times have you experienced one?
Maybe at 1500V you can get away with it but not with real voltage. OTOH the possibility of a gas arc in a tube at 1500V or less is slim to none. I regetter gassy tubes at 1000V. That fuse can be a real HV fuse, a good HB one, a crowbar that instantaneously dumps the PS caps, or whatever else works safely.
Carl,
It still works "Slick" to this day, got one on the bench now (NCL2k)
and I went through it for the cust. just before Dayton. It sure was sweet
then but it came back all "Blowed up" on Halloween. R24 a 220 ohm 1W
was burnt in half which would have removed screen voltage and the
11.5k screen bleeder. (Not good) Still one jug is OK and none of the
screen bypass caps ruptured!
That sort of tells me that the 100 Ohm 1/2W resistor at each socket was replaced by a piece of wire as it should have self destructed long before R-24.
My cure for some customers who refuse to learn how to tune that amp is to limit the screen voltage to 300V in the SSB position as a minimum step or use a current limiter circuit. The RCA 400V spec is too much anyway as its way too easy to get the screen into thermal runaway...its a shitty tube to start with. Use the GS-36B/4CX400A when you run out of 8122's; its a fairly simple conversion.
Ive never seen a blown screen bypass cap except with very early 8122's that had a free standing screen that would lean into the anode when near melting temperature. But the Johnson screen cap rings which I use on 6M conversions sometimes short for unknown reasons. My own NCL-2006 has the same ones I installed in 1964.
Carl
