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#3
05-25-2016, 02:37 PM
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After getting used to putting my Fluke 177 on everything, I started to wonder why most voltages I was measuring were too high compared to the schematics for the tube sets.
The WV77e responded well to a new top-hat diode replacing the selenium and new B+ filter. Four .18 uf in series replace the .047 The 12AU7 was also gassed, likely the reason this VTVM was cast aside. Attachment 191180 The older WV97a is on the left, has the second 6AL5 for a B+ rectifier and AC calibrate. It needs a .1uf @ 1.8kV, so three .33 uf @ 630 v in series make this value. Those leaky batteries are pretty hard on these meters. It may be worth adding an internal bleeder supply using a resistor and 1.55 volt zener diode. Both of these need a set of lead-probes. The Heathkits are really beat up and need them too.
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"When resistors increase in value, they're worthless" -Dave G Last edited by DavGoodlin; 05-07-2018 at 08:11 AM. 
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