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Old 27th October 2020, 10:58 PM   #1
brl0301 is offline brl0301
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Default tseii biasing question

Ive been running my tseii for a while now and all has been great. I decided today to check/adjust my bias since it had been a while. I am seeing some odd behavior while trying to set bias on the right channel. Im running just under 400 b+ and b- is showing around -200. I am trying to set current at 75ma. The left channel is nice and stable but the right channel continues to drift after i make an adjustment.

I checked the bias voltage at the 300b and it is around -66v and is stable even when the tube current is fluctuating. My first thought was the tube was the issue but I swapped tubes and the issue stayed on the same channel.

What should i be looking at to solve this issue? Thanks for any help
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Old 28th October 2020, 02:19 PM   #2
w5jag is offline w5jag  United States
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You might try touching up the solder joints on the resistor you are measuring across; maybe try a different set of test leads or meters to eliminate measurement issues before you suspect the amp.
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Old 28th October 2020, 02:24 PM   #3
w5jag is offline w5jag  United States
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If it is not a measurement issue, then look for a leaky coupling cap on the side that is acting funky.
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Old 28th October 2020, 11:26 PM   #4
brl0301 is offline brl0301
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Quote:
Originally Posted by w5jag View Post
You might try touching up the solder joints on the resistor you are measuring across; maybe try a different set of test leads or meters to eliminate measurement issues before you suspect the amp.
Looks like it was simply a case of a dieing battery in one of my meters. After a fresh battery I was able to get consistant readings and was able to bias the tubes with no issue.

Its funny how something so stupid can create an "issue". Thanks for the suggestions
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