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Old 7th May 2012, 12:27 PM   #1421
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Quote:
Originally Posted by jacco vermeulen View Post
Hola,

at 15A, homes.

For a higher Vf at 0.1A, see the OnSemi MUR3040/60 PTG, not as linear though.

(hope you gents realise that a diode is a semiconductor)
Meaning it will add its on nonlinear characterstics, correct?
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Old 7th May 2012, 12:47 PM   #1422
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Originally Posted by audiok View Post
Is anyone finish F5X ? Can you share the comment , compare with normal F5 ?
Thanks.
this is F5 Turbo thread. not F5X
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Old 7th May 2012, 12:50 PM   #1423
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If you are using k170/j74 from the lower end of the bl grade be careful that the bias does not exceed the Idss.
No one suggests that the bias of a jFET should exceed the Idss.
Some experts have said and repeated the message that operation (implying AC duty cycle) can take them into the Idpk>Idss area.
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Old 7th May 2012, 01:23 PM   #1424
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Old 7th May 2012, 01:26 PM   #1425
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Is "??" asking for more explanation, or is it directed to another post?
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Old 7th May 2012, 01:37 PM   #1426
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Quote:
Originally Posted by buzzforb View Post
I would agree and i think this agrres with the numbers you are getting from the original article. I have even considered J309/271 in the cascode version.
Did you try your alternative N-Channels FETs from Fairchild on the board?
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Old 7th May 2012, 01:48 PM   #1427
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Did you try your alternative N-Channels FETs from Fairchild on the board?
Yes, I am going to have transfer curves of the FQA16n25C vs FQA19n20C in next day or so. I am also going to include the FQP 19n20C in the mix. I have had both FQP and FQN versions on the board, and both have functioned perfectly. The F5/F5T is a REALLY easy build and a great project for first timers IMO. I will be playing music through both channels tonight with bias at 400mV. If all is ok, I am going to hotbox them and see if that changes anything, heeding Jacco's wisdom of real life amp temps. I
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Old 7th May 2012, 03:00 PM   #1428
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Quote:
Originally Posted by buzzforb View Post
Meaning
that numbers on a datasheet are average numbers.

I measure voltage drop on LEDs, zeners and diodes. Matching MOSFETs to 10mV Vgs spread, then hooking it up to a random pick diode bit strange imo, better safe than sorry.

(i compensate lack of wisdom, by thinking up excuses for still having close to 1k in power diode duallies burried in the back yard)
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Old 7th May 2012, 03:39 PM   #1429
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Quote:
Originally Posted by jacco vermeulen View Post
that numbers on a datasheet are average numbers.

I measure voltage drop on LEDs, zeners and diodes. Matching MOSFETs to 10mV Vgs spread, then hooking it up to a random pick diode bit strange imo, better safe than sorry.

(i compensate lack of wisdom, by thinking up excuses for still having close to 1k in power diode duallies burried in the back yard)
Understood. Thanks for adding another step
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Old 8th May 2012, 01:37 AM   #1430
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So i have some disappointing news. I hooked up both versions of the F5T V3 to parallel set of these.

http://www.creativesound.ca/pdf/CSS-...ata-080909.pdf

2ohm and 86dB doesnt make for an efficient load, or so I thought. Both versions with just a single pair of output devices could easily make for an uncomfortable listetning session yet neither version even raised the heatsink temperatures. This reminded me of one of the really great assets of the F5, GRUNT. I am not sure i have enough of a difficult load to push these things. I cannot imagine what the 4 pair version is capable of. I guess i will have to hook both channels up and give a listen tomorrow. A little critique for the group Anybody got any big subwoofers they want to send my way. I guess i can try a pari of parallel ca22rnx's that i have. If that doesnt work, i could try powering my neighbors Prius. Enough screwing around, hope to have more info tomorrow. Interesting point, the freestanding diode version showed no signs of sweating.
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