[Boatanchors] 813 grid to filament short

[Paul Baldock]

I have spare tubes and the rig is back up and running. My question 
was, is this a typical failure in a horizontal configuration. Some 
one mentioned that this is more prone in GE tubes, and coincidentally 
of the 4 this was the only GE tube, Time will tell, and so I continue 
to enjoy great 15 meter conditions on AM "running full legal limit" 
until I run out of 813s.

Thanks

- Paul

At 05:13 PM 10/1/2015, you wrote:
>This is all true and technically it is given a green light if mounted
>with the pins oriented properly.  The problem is some tubes may have
>had manufacturing defects such as the electrodes not quite properly
>aligned and heat plus a horizontal mount exacerbated the problem
>enough to cause a grid - filament short.  This is what I have been
>told; it may not apply in your case.  Sorry you have had difficulty
>with your rig.  The good news is 813s aren't quite the unobtainium or
>expense of 211s or 845s or HF300s.   I'd get another 813 and give it a
>try.  If the bad one was one of the modulator tubes then I'd pull the
>two in the final and use them for audio and run the one good one left
>and the replacement in the final.  This assumes the PA has them
>paralleled and not push-pull.
>
>73
>
>Rob
>K5UJ
>
> >
> >
> > Well I'm an intelligent person, I think. At least intelligent 
> enough to read
> > the manufacturers data sheet that says " in a horizontal position, the base
> > pins No2 and No6 should be positioned vertically one above the other"
> >
> > Then of course there's those beautifully constructed 813 amps in the 1968
> > ARRL handbook
> > 
> http://www.arrl.org/files/file/protected/Group/Members/Technology/tis/info/pdf/68hb195.pdf.
> > Yes the tubes are on their side, and that seems like a quite an intelligent
> > article also.


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