I want to run this by and see what the thoughts are.
Transformer shunt bias, tapping the positive lead of the DMM to the center tap ( still connected ) and the possitive to the plate ( i.e pin 3 on the EL34 ) measuring for 10-40 ma. times your desired reading by the number of tubes then divide in half.
My question is if i build a test rig for monitoring 4 output tubes at one time would there be any adverse effect having each tube shunted threw a meter at the same time? they would all share the center tap connection and then tap off to an independant meter for each tubes plate reading. the math would only be calculated on only one tube but I'm thinking the advantage would be that you can see how each tube is operating without having to poke around inside a live amp to pick the tube you want to base the bias off of. lets be honest matched sets are not exact matches.
Transformer shunt method bias rig
Moderators: pompeiisneaks, Colossal
Transformer shunt method bias rig
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My Daughter Build Stone Henge
Re: Transformer shunt method bias rig
I'm thinking the internal resistance of the meters would most like throw the measurements off.
You are relying on the low resistance of the meter to measure the current.
It would be better to just have a test jack for each plate then plug the meter in one at a time.
You are relying on the low resistance of the meter to measure the current.
It would be better to just have a test jack for each plate then plug the meter in one at a time.
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: Transformer shunt method bias rig
oh well that was what I thought might happen.
will there be any shock to the transformer, tubes or meter during switching? if i built a rotary knob switcher to one meter?
will there be any shock to the transformer, tubes or meter during switching? if i built a rotary knob switcher to one meter?
My Daughter Build Stone Henge