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F6 Illustrated Build Guide
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Old 7th October 2015, 11:22 PM   #101
audioexplorations is offline audioexplorations  Belgium
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Will need to measure them. They were the b grade matched pair from the store.

5.1V zener is giving me max 70mV bias (cold), will pop the 6.2V in with the 3.3K resistors.
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Old 7th October 2015, 11:31 PM   #102
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Quote:
Originally Posted by audioexplorations View Post
Will need to measure them. They were the b grade matched pair from the store.

5.1V zener is giving me max 70mV bias (cold), will pop the 6.2V in with the 3.3K resistors.
Best to know what Idss you have it could happen again.
I'd keep them under 9mA. Nelson recommends 8mA.
Zen Mod suggested putting a clip on heatsink which is worthwhile.
Either way you want to keep them under 55 degrees in my opinion.
How hot do they feel to the touch?
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Old 8th October 2015, 12:56 AM   #103
audioexplorations is offline audioexplorations  Belgium
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I'll have a feel tomorrow when I get the amp back up and running. The 6.2v zener with 3.3K resistor biases beautifully, very nice and stable. I almost destroyed the amp PCB when pulling out the 5.1v zener, the copper strip lifted off the surface of the PCB by about 1mm. Got lucky that it all stayed in tact. Not sure I'd be able to get away with pulling out the zener a 3rd time...
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Old 8th October 2015, 03:31 AM   #104
abadsantos 7 is offline abadsantos 7  Philippines
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Quote:
Originally Posted by audioexplorations View Post
I'll have a feel tomorrow when I get the amp back up and running. The 6.2v zener with 3.3K resistor biases beautifully, very nice and stable.
Hi,

Since you have both experienced the 9.1V and 6.2V, How would you compare the bias stability between the two zener?

I have build my F6 using the 6.2V zener though Im using 5K. Bias
is quite stable too.

Cheers.
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Old 8th October 2015, 04:38 AM   #105
2 picoDumbs is online now 2 picoDumbs  Australia
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Quote:
Originally Posted by abadsantos 7 View Post
Hi,

Since you have both experienced the 9.1V and 6.2V, How would you compare the bias stability between the two zener?

I have build my F6 using the 6.2V zener though Im using 5K. Bias
is quite stable too.

Cheers.
5k is perfectly fine.
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Old 8th October 2015, 08:12 AM   #106
noelectrix is offline noelectrix  Europe
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are the VISHAY IRFP 240 ok for this amp or do you recommend any other brand?
IR would be the other brand im able to buy.

I plan to buy a tiny batch of 25 pieces and try to get the best matched out of it.
Never did matching before so Ive no experience how much to buy.

stefan
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Old 8th October 2015, 08:16 AM   #107
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I'm using Vishay. I was under the impression that Vishay bought out IR, so these devices should be identical.
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Old 8th October 2015, 08:24 AM   #108
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Originally Posted by noelectrix View Post
I plan to buy a tiny batch of 25 pieces and try to get the best matched out of it.
Never did matching before so Ive no experience how much to buy.

stefan
25 is plenty although matching is not really that critical for F6.
Try and get them from the same manufacturing batch packaged in a tube, you will get better matching that way.
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Old 8th October 2015, 08:34 AM   #109
noelectrix is offline noelectrix  Europe
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Quote:
Originally Posted by 2 picoDumbs View Post
25 is plenty although matching is not really that critical for F6.
Try and get them from the same manufacturing batch packaged in a tube, you will get better matching that way.
thats what i do and 25pcs is the smallest batch i can order. i just hope its not just 25 pieces, randomly packed out of a mixed huge bucket, but rather 25 nicely packed straight from production. Ill see

thanks for ur opinion,
st.
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Old 8th October 2015, 08:50 AM   #110
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Quote:
Originally Posted by noelectrix View Post
thats what i do and 25pcs is the smallest batch i can order. i just hope its not just 25 pieces, randomly packed out of a mixed huge bucket, but rather 25 nicely packed straight from production. Ill see

thanks for ur opinion,
st.
Looks like standard package in a tube is 25 from digikey.
They should be from the same batch (touch wood) as that is how the manufacturer packages them
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