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Old 20th January 2013, 01:28 PM   #9071
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what are you using as a output coupling cap
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Old 20th January 2013, 01:30 PM   #9072
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Buzz, you can't get a voltage across the collector if you can't have spare current for its 2K2 load is a suspicion. That can occur if your input Jfets are stronger and drop much over the 1K5 resistive CCS. Try trimming B+ slowly up on the SSLV while watching the collector to ground voltage. See if it will start showing up at a point. So we can have a picture of this assumption.
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Old 20th January 2013, 01:33 PM   #9073
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I have a range if 3.5V to 8.75V using the trimmer.
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Old 20th January 2013, 01:33 PM   #9074
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Quote:
Originally Posted by RCruz View Post
Hi buzz

Seems you might have trouble with the first stage Voltage setting trimmer.

I once did not get Q2 collector voltage because the trimmer did not go low enough.
That ties with the above. If its drawing more 1st stage 1K5 CCS current than designed even at zero trimmer, its not enough.
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Old 20th January 2013, 01:34 PM   #9075
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Quote:
Originally Posted by buzzforb View Post
I have a range if 3.5V to 8.75V using the trimmer.
Where is that range? At TP2?
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Old 20th January 2013, 01:41 PM   #9076
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In my drawing the bjt is loaded with 1.5k. The bf845 cs has a 2.2k load. Ill tryt rimming main voltage.
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Old 20th January 2013, 01:42 PM   #9077
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TP1
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Old 20th January 2013, 02:01 PM   #9078
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1k5 is feeding the fets, 2k2 loads the bjt's collector to ground is the correct thing. TP1 changing means there is variability because there is no constant voltage (Leds+Vbe) provided by the bjt. Watch TP2 with a DMM as long as providing increasing B+ after you make sure the 1k5 and 2k2 resistors are configured as I mentioned.
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Old 20th January 2013, 02:03 PM   #9079
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Quote:
Originally Posted by buzzforb View Post
In my drawing the bjt is loaded with 1.5k. The bf845 cs has a 2.2k load. Ill tryt rimming main voltage.
BF245's 2k2 and 100uF to ground is an RC filter, not a load.
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Old 20th January 2013, 02:10 PM   #9080
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It is arranged as you say. Ill reportback.
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