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Old 3rd December 2011, 06:40 PM   #481
M Gregg is offline M Gregg  United Kingdom
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Ok here is half 6c33c..

using True RTA ,,not set up just as a signal gen..at 1Khz

All readings are with a X10 probe so you have to multiply...

Obviously it gets more distorted as you increase input..

The first one is 5.5V
Second is at 11V
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File Type: jpg half at 5.5v (449x600).jpg (198.7 KB, 204 views)
File Type: png True RTA.PNG (122.5 KB, 198 views)
File Type: jpg half 11v (449x600).jpg (210.2 KB, 190 views)
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Old 3rd December 2011, 06:47 PM   #482
M Gregg is offline M Gregg  United Kingdom
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Full 6c33c..

At 8/9/10/11/12V...I did manage 13V however the 1.6A T fuse blew..so no picks ...didn't want to try it again..drawing 1.7A
Again X10 probe so you have to multiply..


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Attached Images
File Type: jpg 7V (449x600).jpg (201.5 KB, 186 views)
File Type: jpg 8V (449x600).jpg (207.3 KB, 161 views)
File Type: jpg 9v (2) (449x600).jpg (199.0 KB, 24 views)
File Type: jpg 10v (449x600).jpg (195.2 KB, 20 views)
File Type: jpg 11v (449x600).jpg (198.5 KB, 17 views)
File Type: jpg 12V (449x600).jpg (197.5 KB, 16 views)
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Old 3rd December 2011, 06:51 PM   #483
M Gregg is offline M Gregg  United Kingdom
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low distortion on half 6c33c

Is app 3.78w

flat out is app 15w
-------------------------------------------
flat out is 15watt

------------------------------------------------------------
Full 6c33c..
Low dist 8watt

flat out is 21Watt

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M. Gregg
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Old 3rd December 2011, 06:59 PM   #484
M Gregg is offline M Gregg  United Kingdom
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Tried to do 10khz square wave and 25k..

however the True RTA makes a right mess of it looks like triangular..

So I will have a look at it with a sig gen..


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Old 3rd December 2011, 07:17 PM   #485
M Gregg is offline M Gregg  United Kingdom
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10khz..square wave.
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Old 3rd December 2011, 07:25 PM   #486
M Gregg is offline M Gregg  United Kingdom
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20khz square wave..

Could do with a tweek to sharpen the edges..
Could be the coupling caps to the 6c33c's..looking to change them,,




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Old 3rd December 2011, 07:47 PM   #487
M Gregg is offline M Gregg  United Kingdom
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Half 6c33c 10khz square wave..

The scope leads arn't the best my others got squashed in the loft...
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Old 3rd December 2011, 07:56 PM   #488
M Gregg is offline M Gregg  United Kingdom
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Half 6c33c at 20hz

just for fun..
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Old 3rd December 2011, 07:58 PM   #489
M Gregg is offline M Gregg  United Kingdom
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Here it is..
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Old 3rd December 2011, 08:33 PM   #490
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Well, Thats all pretty interesting!

I really should get my scope out and do some tests too. It would be interesting to see where the onset of distortion is actually happening above 8W, whether in the driver or the O/P stage...
--Have to open the FB loop to do that though, and alter I/P level accordingly...

To sharpen up the square-waves, it may be worth dropping the value of the PI grid-coupling resistor to 100K, (or just link it out) in view of what a previous poster mentioned concerning the Miller capacitance of that stage....

Worth trying anyway, see if it makes a difference...
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