Where the intermittent connection bring about a short across the
heater supply, is it robust enough to carry the short circuit
current and take out a 15A fuse? I'd guess that the arcing when
the contact occurred might cause further damage.
Can you rearrange the circuit to remove the dc connection between
heater and cathode, so it doesn't matter where in the tube an
intermittent connection crops up?
Steve
> Earlier, I had posted a comment about being able to "bring life back" to my
> 8877 tubes where they had developed an intermittent short between cathode
> and filament.
>
> One astute observer thwarted my thinking with this set of hypotheticals.
> I'm withholding the name as he replied privately: Here are the two
> possibilities presented:
>
> "Example 1: 8877 has a short between left pin filament and cathode.
> A hard connection to the left pin and the world seems to be OK.
>
> Example 2: The tube has a short cathode to the right pin. A hard
> connection cathode and left pin will make a short of transformer via choke.
> Current flows from the right pin to the wired connect to the left.
> Both pins are now tied together. Danger for burning out, who is
> stronger choke or transformer?"
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