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Old 18th December 2012, 08:12 PM   #1231
DimZ is offline DimZ  Greece
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Originally Posted by Salas View Post
Maybe it draws much. Try boost the CCS at say 70mA to see if it holds before other investigations.
give me 5 min to report back ....
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Old 18th December 2012, 08:12 PM   #1232
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Its OK. How are the + pair hooked?
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Old 18th December 2012, 08:20 PM   #1233
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the + pair tied together then splits to 2*10k parallel anode resistor per tube ....
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Old 18th December 2012, 08:25 PM   #1234
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That's OK too. Was it 335V until the heaters really booted up off their Isource reg?
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Old 18th December 2012, 08:30 PM   #1235
DimZ is offline DimZ  Greece
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yes, then droped to 240V ..

trimed for 70mA but by mistake I turned r11 anti-clockwise ...

shall I put it at 340V ?

840 sink cold (not ice ...) ...
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Old 18th December 2012, 08:32 PM   #1236
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340 is OK.
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Old 18th December 2012, 08:34 PM   #1237
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How high a reg input DC you got to work from?
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Old 18th December 2012, 08:42 PM   #1238
DimZ is offline DimZ  Greece
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input dc is 360V ...

with R4 at 70mA trimed R11 ... only reaches 300V ...
dc offset still varies ...
I think i smelled something like smoke (not sure) ... turned off power ...
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Old 18th December 2012, 08:45 PM   #1239
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There is strong biasing. It may be up to 30-35mA per tube though and not be abnormal. The fact that you can go up for B+ as you allow more CCS shows there is current demand in the output for one thing.
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Old 18th December 2012, 08:47 PM   #1240
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Keep a second DMM on one cathode resistor and if you got a third one on the other so to estimate bias current by voltage/680R.
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