IF YOU DO HAVE A CRT TESTER, USE IT. FOLLOW THE INSTRUCTIONS ON YOUR TESTER. FAILURE TO DO SO COULD RUIN THE TUBE.
AFTER YOU PUT THE TUBE ON THE TESTER, GIVE IT TIME TO WARM UP. DON'T BE SURPRIZED IF YOUR TUBE SHOWS LOW EMMISSION. TUBES THAT HAVE BEEN UNUSED FOR MANY YEARS CAN ACT DEAD. RAISE THE HEATER VOLTAGE BY ABOUT TWO VOLTS AND LET IT COOK. LET IT COOK FOR SEVERAL HOURS IF NECESSARY. IF THE EMISSION COMES UP TO THE GOOD RANGE, THEN LOWER THE VOLTAGE BACK TO ITS RATED VOLTAGE, IN MOST CASES, 6 VOLTS. THE EMISSION SHOULD STAY RIGHT WHERE IT IS. IF SO, THE TUBE IS MOST LIKELY GOOD. IF THE EMISSION FALLS, DON'T GO LOOKING AT eSnipe YET. RAISE THE VOLTAGE AND LET IT COOK SOME MORE. I HAVE HAD TUBES RUN ON THE TESTER FOR AS LONG AS A WEEK, MAINLY BECAUSE I FORGOT I HAD THE TESTER PLUGGED IN. IF YOU DO NOT HAVE A CRT TESTER, YOU CAN HOOK UP A FILAMENT TRANSFORMER AND COOK IT THAT WAY. YOU MUST HAVE A TUBE DATA MANUAL. YOU CAN RUN A CONTINUITY TEST ON THE FILIMENTS. GETTING CONTINUITY DOESN'T PROVE SQUAT. ALL IT PROVES IS THE FILAMENTS WILL LIGHT UP.
YOUR CRT TESTER WILL HAVE A "REJUVENATE" FUNCTION. SOME CRT TESTERS' REJUV FUNCTION ACTUALLY DESTROYS THE TUBES. DO NOT USE IT UNLESS IT'S THE ABSOLUTE LAST RESORT. MANY OF THE TUBES FROM THE 50'S AND 60'S WILL RESPOND WELL TO REJUVENATION. IF YOUR TUBE STAYS IN THE GOOD RANGE AFTER THE COOK, DON'T EVEN THINK OF REJUVENATION.
IF YOUR TUBE HAS A BRIGHTNER ON IT, THAT COULD SPELL TROUBLE. CHECK IT AND SEE. THE LONG COOK AT INCREASED HEATER VOLTAGE MAY GIVE IT MORE LIFE, THEN AGAIN, MAYBE NOT. RESTORE THE CHASSIS AND TRY IT. IF THE TUBE IS DIM AFTER THE COOK, REINSTALL THE BRIGHTNER. IF THIS IS THE CASE, THE TUBE IS ON ITS LAST LEGS.
THERE ARE SOME CASES WHERE THE TUBE CHECKS GOOD ON EMISSION BUT LOOKS LIKE SHIT ANYWAY. IF THE PICTURE "BLOOMS" ON FULL BRIGHTNESS, OR IF IT WON'T FOCUS CORRECTLY, CHANCES ARE, THE TUBE IS GASSY. START LOOKING FOR A REPLACEMENT. GASSY TUBES ARE LOSING THEIR VACUUM. NO COOK OR REJUVENATION WILL SAVE THEM. FIND A REPLACEMENT AND SAVE THE DUD. YOU COULD GET IT REBUILT.
I DID HAVE TUBES THAT HAVE BEEN DORMANT CHECK GOOD AT THEIR RATED HEATER VOLTAGE. THIS IS A GOOD THING. IF YOUR TUBE IS INDEED GOOD, RESTORE YOUR SET.
I RECENTLY WENT ON A PICTURE TUBE TESTING FRENZY. OF ALL MY SETS, I NEED TUBES FOR ONLY TWO. MOST OF MY TUBES WERE GOOD ANYWAY, AND A COUPLE CAME BACK AFTER A NICE COOK.