[AMRadio] Intermittent Filament

Rick Brashear rickbras at airmail.net
Mon Sep 17 22:51:23 EDT 2007

I have a 828 pentode with an intermittent filament.  When I tap on the glass
it will usually stay lit as long as power is applied and sometimes comes
back on when I've removed power.  When it's lit it works beautifully.  It
seems I've heard guys talk of a hit and miss method of restoring filaments
in some cases.  Does anyone know anything about this?  I know we used to
rejuvenate picture tubes by applying certain voltages to them.  I think I
still have my old CRT rejuvenator/checker around here some where.

Any info would be much appreciated.


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