Tube Tester Question

[Raccoon]

I love tube equipment , so I have a lot of it around the house , I have for years . Problem is , I've never owned a tube tester , until now . I finally broke down and bought a really nice "B&K Dyna Quik 600" tube tester . It's in beautiful condition , still has all of it's original paperwork , as well as 4 B&K Dynascan Adapters . I've been testing all my tubes like a mad man since it arrived ... lol .

One of my tubes read at 100% , but it says it has a short on 4 pins (I think it was 2, 3, 7 & 8 if I remember right) ... the tube is a 12AT7 . I tried looking up any information I could find about vacuum tubes with shorted pins , but I had absolutely no luck at all . So I thought I'd ask here , is this tube still usable , what (if any) issues could come from continuing to use a shorted tube ? I mean , I don't think any good could come from using it . I'm just trying to find out more information about shorted pins when we find them on vacuum tubes while we're testing them . And no , I'm not still using that tube ... I replaced it . Again , I don't think any good could come from using it ... lol

Thanks

 

[Captain Kilowatt]

The 12AT7 is a dual tube. You should see a short on pins 4,5, and 9 which is a centre tapped filament. Also you should see a short on pins 2 and 7 which is the grid. There should be no other shorts.

 

[Raccoon]

View attachment 61769
The 12AT7 is a dual tube. You should see a short on pins 4,5, and 9 which is a centre tapped filament. Also you should see a short on pins 2 and 7 which is the grid. There should be no other shorts.

I double checked the tube , and it has a short at pins 2, 3, and 7

 

[Captain Kilowatt]

I double checked the tube , and it has a short at pins 2, 3, and 7

Verified with an ohmeter? If so you have a cathode to grid short. Throw it away.

 

[nomadradio]

The rule for our Hickok computerized tester is never press a "test" button if any of the four short lights come on. Bad things could happen.

Doesn't matter how the short developed inside the tube, just means it won't work properly in the equipment.

73

 

[Roger Dodger]

The 600 is a basic model most notably known for its excellent grid leakage test. Its emissions test isn't that accurate compared to better testers but it's adequate. It won't indicate GM so if you should someday need that feature, best get the better model Hickoks or Sencore MU150. The Sencore is a darn good tester, especially when refurbished & calibrated & often priced lower than many Hickoks. Smaller package & robust construction too.