[Boatanchors] More on Carbon Comp V ratings

[Bill Cromwell]

Hi Barry,

Use the parts list as a guide to the power rating you need for those 
resistors. The resistors that are in the power supply bleeder will see 
B+ across them (and get hot) but those are usually two or three in 
series. Not always. They are big, fat, "long" resistors. Your screen 
dropper is NOT going to have a lot of current going through it. One end 
might be 600 volts above ground but the other other end is NOT at 
ground. Grid leakers/grid bias resitors don't get a lot of power applied 
either. The same for resistors from cathode to ground for bias.

The arc over problem with high voltages that actually are *across* the 
resistor relies on the distance the spark must jump to go around. Some 
of the parts for higher voltages have ribs on the surface to increase 
that distance. Those are not cooling fins. As tube power supplies go 600 
volts is not terribly high. Just don't put your body parts *across* it!

73,

Bill  KU8H

On 02/15/2018 10:16 AM, Barry Pfeil wrote:
> Wow, you guys really like to go at it!  Thanks for all the info and
> opinions on my first post.  Getting back to my little Adventurer, FYI the
> parasitic chokes are actually wound on 100 ohm resistors and, since I can't
> measure them in-circuit (DC short) I'll probably replace them just to be
> sure since half the other carbon comps in the rig are way high.  But some
> of the other bad resistors WILL definitely see B-plus, which is 600V in
> this rig, so my question about resistor voltage ratings still stands,
>  David (K6XYZ?) suggested Ohmite OX or OY.  Any other thoughts?
>
> BTW, nice to see those 50 year old 10W wire wounds made by IRC are still
> right on the money in resistance value.
>
> Thanks again ES 73,
> Barry K6RM
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-- 
bark less - wag more