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Old 20th March 2012, 12:17 AM   #1
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Default F5 bias

hello i have 2pc 225VA transformers in my F5. and a bias of about 1.72A(cviller's dual output's) and the transformer(only one ch yet) is nice and cool. about 32C.
anyone have an idŤ of how much i can crank the bias with those transformers? heatsinks is also nice and cool. maybe 37-38C ambient is about 22-23C.
rigth now bias is 1.72A. DC ofsett -0.4mV- +0.4mV
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Old 20th March 2012, 12:24 AM   #2
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up to 50W per mosfet
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Old 20th March 2012, 12:30 AM   #3
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50W pr mosfet on a 225VA?
thats 200W. i don't want to boil the transformers
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Old 20th March 2012, 12:35 AM   #4
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225 VA is not much to go on as it is the voltagge time current
so what voltagge is it?

If it is split secondary at 18 and 18 V 225 divided by 36 = 6.25 A total
Or you can take max 3.125 A out of each secondary

Papa reccomend a 3 to 1 margin so in respect to that you are already taking out enough.

rest is again realy meaningless as what size heath sink?
and ofset again got nought to do with it as it all down on how carefull you are when tweaking the pots.

If you go Papa class you need bigher trafoss
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Old 20th March 2012, 12:37 AM   #5
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Still mighty Zen is right
50 W on each mosfet is max that is the given trought
Boiled trafoss irellevant we have them for breakfast
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Old 20th March 2012, 12:52 AM   #6
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I meant you wrote one 225 Watt-er per channel

so - if using original F5 schm , where you have 2 mosfets per channel , that means you're still in ballpark - 100W power consumption per 225W iron
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Old 20th March 2012, 01:00 AM   #7
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225VA pr ch. 4 mosfets pr ch
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Old 20th March 2012, 01:36 AM   #8
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yes it is 2x18V transformer. so +/-22-23V no itd 1.72A bias. and the transformeris at about 32-34C witch is about 80W i think it will have no broblem with at least 120W.
BTW. it sounds fantastic. i just love it. but it's too cool
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Old 20th March 2012, 01:39 AM   #9
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here it is
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Old 20th March 2012, 01:45 AM   #10
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the whole thing
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