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Precise 111m tube tester restoration
#17

Thanks Bob! This has been a challenge. A little different than a radio, but hopefully this will play a hand in the restoration of lots of radios, TVs and other vintage electronic gear. I got to studying on the jumpy meter. It seems this meter is very sensitive, and likes to act like a windshield wiper when it starts to measure, bouncing back and forth several times before settling. It also seems a little unstable during a test. Bugs me. So, I set up a Simpson meter beside it and watched things. It looks like it is tracking the line voltage. Maybe even amplifying it. Someone from ARF mentioned his was the same way, so I take it this is the personality of this tester. I have been through it, checking for bad solder connections and dirty switch contacts. I also noticed my old 111 and Jackson did about the same thing.

 So, I did some experimenting and came up with this: I found that a large value, low voltage electrolytic capacitor put parallel to the meter (across the existing 100mf cap) made a world of difference in the behavior. I found that a 1000mf on up made things behave a lot better. I had the best results using a 4700mf, 10v cap. The best place I found to connect this was across the center lugs of the meter reverse switch.
   
It seems to be working really well.
I have calibrated it, and need to move on to the cabinet. I am still looking for any tube data updates.

If I could find the place called "Somewhere", I could find "Anything" Icon_confused

Tim

Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44


Messages In This Thread
Precise 111m tube tester restoration - by TV MAN - 05-27-2016, 10:00 AM
RE: Precise 111m tube tester restoration - by TV MAN - 08-13-2016, 05:10 PM



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