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Old 27th February 2005, 04:54 PM   #11
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How mutch should i increase R1 and R2, RA and RK on the phase splitter ? Maybe 47K or 100K ?
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Old 27th February 2005, 05:07 PM   #12
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How mutch should i increase R1 and R2, RA and RK on the phase splitter ? Maybe 47K or 100K ?
47k is a good value.

Regards Hans
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Old 27th February 2005, 05:14 PM   #13
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Ok, thanks tubetvr OT: Tubetvr, do you live in sweden too ?
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Old 27th February 2005, 05:17 PM   #14
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More updates on the schem, Is more improvements possible ?
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Old 27th February 2005, 08:31 PM   #15
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New update, the feeds to the output tubes screen grids are separated. Tell me what you think:
Click the image to open in full size.
Im satisfied, cir maker shows a nice sinewave, i dont know how true it is. Theres only one way to find out, i am going to start building it slowly. I will take pics. Wish me luck.
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Old 28th February 2005, 06:42 AM   #16
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OT: Tubetvr, do you live in sweden too ?
I have just moved back to Sweden after living 8 years in Japan, we plan to stay here a couple of years at least after that maybe somewhere else.

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New update, the feeds to the output tubes screen grids are separated. Tell me what you think:
You should try to keep the screen voltage as stable as possible, a voltage regulator is a good idea as the screen current varies with the envelop of the signal, it could be just 2 voltage regulator tubes type 0A2 in series is good and very easy to use. As this is a class AB1 amplifier another good idea is to use a choke input supply for the B+ to keep the voltage more stable. It all really depends on what kind of final result you strive for.

Also shift C4 and C5, (I mixed them up earlier)

Regards Hans
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Old 28th February 2005, 07:42 AM   #17
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Ok, i dont have any stabilizing tubes. Maybe its just in the simulator it varies, it might be stable in reality, ill find out when im done with it.
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Old 28th February 2005, 08:17 AM   #18
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Maybe its just in the simulator it varies, it might be stable in reality, ill find out when im done with it.
Both thee anode current and the screen current will vary with the envelope as long as you dont run the tubes in class A, with the operating point you have choosen the current will vary.

See here for data on 6L6 with a very similar operating point, http://www.mif.pg.gda.pl/homepages/f...064/6/6L6G.gif See the column at the far right with 400V anode and 300V screen, as you can see the anode current, (for 2 tubes) varies between 102 - 152mA and the screen current between 6 - 17mA, as the anode current varies the anode voltage will vary and with that also the screen voltage. Performance of a class AB amplifier with tetrodes always improves when the screen voltage is stabilised.

Edit, If you dont have regulator tubes you can use zeners or build a simple solid state regulator, something simple like this is better than nothing http://www.bonavolta.ch/hobby/en/aud...id%20State%202 check "solid state 2"


Regards Hans
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Old 28th February 2005, 09:59 AM   #19
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Now i dont have the components to build those, would it be mutch difference ?
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Old 28th February 2005, 10:01 AM   #20
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A nice solid screen supply would be nice, but it will of couse work without it (as in the old days). It is something you could add later when you have the parts, anyway.
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