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PP CFB toroidy OPT
PP CFB toroidy OPT
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Old 29th November 2018, 04:33 PM   #21
LKA is offline LKA  Europe
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The power section is finished. Everything works as expected.
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Old 29th November 2018, 08:38 PM   #22
Lingwendil is offline Lingwendil  United States
Now with high-fructose ASSAULT-gluten!
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PP CFB toroidy OPT
Gorgeous.
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Old 30th November 2018, 09:17 AM   #23
LKA is offline LKA  Europe
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Thanks, you little exaggerate
I'm not sure what driver to use. Two LTP or single triode plus LTP ?

This is the latter design.
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File Type: png PP1-DRIVER-pcb-view.png (139.3 KB, 385 views)
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Old 30th November 2018, 04:14 PM   #24
Lingwendil is offline Lingwendil  United States
Now with high-fructose ASSAULT-gluten!
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PP CFB toroidy OPT
You're too modest! That is some very clean, concise, and professional work.
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Old 1st December 2018, 01:04 AM   #25
multi is offline multi  Australia
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Amazing work; looks Great
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Old 10th March 2019, 10:08 PM   #26
tomlang is offline tomlang  United States
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Any updates to this? How did the CFB Toroidy's perform?
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Old 11th March 2019, 06:43 AM   #27
LKA is offline LKA  Europe
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Well, 2-3 weeks ago I finished the driver board and measured the whole amp. It is better than expected even though output tubes were JJ KT77.
Later I will upload more graphs, here you can see 20Vpp 20kHz sqr signal into 4R5, non-gnfb.

PP1-ngnfb-sqr20k-4R5.jpgPP1-desk1.jpgPP1-driver-001.jpgPP1-driver-003.jpgPP1-driver-004.jpg
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Old 11th March 2019, 09:26 AM   #28
gregt is offline gregt  New Zealand
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nice work. I assume that the squarewave is with just Cathode feedback around output. What level of global feedback do you propose to deploy. Keen to see more
...very nice work
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Old 11th March 2019, 11:32 AM   #29
LKA is offline LKA  Europe
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Yes, the sqr20k above is just with CFB. Below with 12dB global feedback + CFB.

PP1-UL-KT77-GNFB-sqr20-4R5-20Vpp.pngPP1-UL-KT77-GNFB-sqr100-4R5-20Vpp.pngPP1-UL-KT77-GNFB-sqr1k-4R5-20Vpp.pngPP1-UL-KT77-GNFB-sqr10k-4R5-20Vpp.pngPP1-UL-KT77-GNFB-sqr20k-4R5-20Vpp.png
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Old 11th March 2019, 12:07 PM   #30
LKA is offline LKA  Europe
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frequency response at 30Vpp into 4R5 (UL+CFB+GNFB_12dB)
17Hz: 0dB
100kHz: -3dB

PP1-UL-KT77-GNFB-sin17-4R5-30Vpp.pngPP1-UL-KT77-GNFB-sin100k-4R5-30Vpp.png

thd vs freq at 10W into 4R5
green trace: UL+CFB+GNFB_12dB
gray trace: TR+CFB+GNFB_12dB

PP1 10W 4R5.png

Last edited by LKA; 11th March 2019 at 12:10 PM.
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