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841/KT88 Unity-Coupled Amp Update
841/KT88 Unity-Coupled Amp Update
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Old 30th July 2020, 02:36 PM   #1
SpreadSpectrum is online now SpreadSpectrum  United States
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Default 841/KT88 Unity-Coupled Amp Update

I updated my Unity-Coupled amp and wrote up a detailed account here.

I've attached a simplified schematic and some distortion test results.

Summary Below:
100mW: 0.030%
500mW: 0.040%
1W: 0.044%
2W: 0.084%
5W: 0.12%
10W: 0.16%
Attached Images
File Type: jpg IMG_20200715_124223144.jpg (1.00 MB, 211 views)
File Type: jpg UC_841.jpg (120.5 KB, 226 views)
File Type: jpg IMG_20200729_195748833.jpg (322.1 KB, 220 views)
File Type: jpg IMG_20200729_195823226.jpg (577.8 KB, 205 views)
File Type: png R100m.png (105.9 KB, 212 views)
File Type: png R500m.png (106.5 KB, 47 views)
File Type: png R1W.png (108.9 KB, 36 views)
File Type: png R2W.png (108.5 KB, 26 views)
File Type: png R5W.png (109.0 KB, 24 views)
File Type: png R10W.png (107.1 KB, 26 views)
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Old 30th July 2020, 03:17 PM   #2
astouffer is offline astouffer  United States
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I applaud your numerous test loops for probing signals.
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Old 30th July 2020, 05:31 PM   #3
SpreadSpectrum is online now SpreadSpectrum  United States
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Yeah, they're handy for that, but I've started using them for soldering wires to boards generally. I've never liked poking a wire into a hole and soldering, and I like the idea of a soldered connection better than a screw terminal.
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Old 1st August 2020, 12:28 AM   #4
gorgon53 is offline gorgon53  Finland
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841/KT88 Unity-Coupled Amp Update
Nice results, congrats.
May I ask, is the PAT1070-UC dc resistance of all 4 primaries exactly the same?
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Old 1st August 2020, 02:06 PM   #5
SpreadSpectrum is online now SpreadSpectrum  United States
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Quote:
Originally Posted by gorgon53 View Post
Nice results, congrats.
May I ask, is the PAT1070-UC dc resistance of all 4 primaries exactly the same?
No, I added resistors to make them all equal. There were variances of 1 Ohm or so. Each one was ~20 Ohms for a total resistance of around 80 Ohms.
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Old 3rd August 2020, 12:22 AM   #6
gorgon53 is offline gorgon53  Finland
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841/KT88 Unity-Coupled Amp Update
Ok, Thank You!
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