[Amps] SB 220 Exploding Resistor

[Vic Rosenthal]

This is a 'glitch resistor' intended to protect tubes and other components against arcs caused by gassy tubes. You might replace it with a 25 or 50 ohm 50w resistor and it will work fine, if the tubes survived the arc that blew it up. I have seen this happen with no apparent ill effects. On the other hand, a tube might be gassy and arc again, or the grid may have been damaged by the arc. Check the components connected between the grids and ground; they are often damaged by plate-Gris arcs.

Vic 4X6GP/K2VCO

> On 17 Jan 2016, at 6:05 PM, Tom Hellem <tom.hellem at gmail.com> wrote:
> 
> Hi-
> My SB 220 has what appears to be a glass coated wirewound resistor in
> series with the anode B+
> supply lead just before the RF chokes. It is not on the schematic so must
> have been a modification
> done at some point. It blew up in spectacular fashion one day and I
> hesitate to just replace it without
> having some idea of what may have been the root cause. I do not have much
> of an electronics background
> and would appreciate if someone could suggest some things that I should
> check out before I try to put it
> back on line.
> 
> 73 To All on The List.
> 
> Tom
> K0SN
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