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Old 27th August 2011, 04:26 AM   #421
EUVL is offline EUVL  Europe
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As I mentioned, this is a rare opportunity to have such a large batch of 2SJ74s to match from.
Spencer has already done the hard work for you. Now you have 160 pre-selected FETs.
I can only encourage you to do the 3-point measurement in post # 402 for even better match within each of the 4 groups.


Patrick
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Old 27th August 2011, 08:42 AM   #422
NicMac is offline NicMac  Italy
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Quote:
Originally Posted by Nikon1975 View Post
Here it comes another thing I had in mind: the ultimate flexibly pre-amp, to mix balanced and un-balanced source and amps.

D.
Have a look at the Relaixed2 pre-amp/attenuator. Really a great design. I have modified it so that one of the balanced inputs is used as line-out.
Cheers,
Nic
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Old 27th August 2011, 12:47 PM   #423
JBdV is offline JBdV  Netherlands
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I want to do a 3 point test in one batch first.
Also looking into the Elektor curve tracer now...
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Old 27th August 2011, 01:38 PM   #424
ashaw is offline ashaw  Australia
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I also have 8 matched quads coming here, these are in the 6.80 6.85 8.00 8.05 range.
with the same pre-screaning that was done for JBdV, I hope that I get some good matches.
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Old 27th August 2011, 04:12 PM   #425
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Jan, me too! Let me/us know the payment arrangements......
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Old 27th August 2011, 06:47 PM   #426
NYCOne is offline NYCOne  United States
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Quote:
Originally Posted by NicMac View Post
Have a look at the Relaixed2 pre-amp/attenuator. Really a great design. I have modified it so that one of the balanced inputs is used as line-out.
Cheers,
Nic
I just bought this balanced input selector, volume controller and I'm trying a Borbely preamp the the UGS in it. The nice part is it saves a lot of time vs trying a full blown PIC or Amtel build.

I bought it through Taobao, it was about $140 USD. It comes built to your specs (I specified my resistors and display color - blue). PM for more details.
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Old 27th August 2011, 07:17 PM   #427
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Location: Spain
Quote:
Originally Posted by JBdV View Post
Spencer has shipped 40 quads matched 70/74 fets to me.
They are grouped in 4 current ranges:


Group K170 J74
1 6.90 6.95 8.10 8.15
2 6.95 7.00 8.15 8.20
3 7.00 7.05 8.20 8.25
4 7.05 7.10 8.25 8.30

He also did a transconductance comparison within the K170 and the J74 groups.

These quads are most likely the best suitable parts he could provide based on his new batch of 2000 J74's for the F5X. (J74 is likely close to becoming obsolete)
K70 is still available in big quantities.

I am happy to offer these for cost to all F5X builders, that have already ordered the cases.
Im interested also.
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Old 27th August 2011, 11:54 PM   #428
Studley is offline Studley  United Kingdom
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Location: West Riding of Yorkshire, England
Quote:
Originally Posted by JBdV View Post
Spencer has shipped 40 quads matched 70/74 fets to me.
They are grouped in 4 current ranges:


Group K170 J74
1 6.90 6.95 8.10 8.15
2 6.95 7.00 8.15 8.20
3 7.00 7.05 8.20 8.25
4 7.05 7.10 8.25 8.30

He also did a transconductance comparison within the K170 and the J74 groups.

These quads are most likely the best suitable parts he could provide based on his new batch of 2000 J74's for the F5X. (J74 is likely close to becoming obsolete)
K70 is still available in big quantities.

I am happy to offer these for cost to all F5X builders, that have already ordered the cases.
I'm interested, many thanks
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Old 27th August 2011, 11:58 PM   #429
triode4 is offline triode4  United States
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Count me in for a set of the 3rd row.Thankyou!
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Old 28th August 2011, 12:23 AM   #430
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Quote:
Originally Posted by ashaw View Post
Probably could be done, that is however about $500 in copper ingots, and that is before the milling fees. I would however get about half of that back when I sell the scrap copper to a metal reclaimer... perhaps.
Now who has such a large Milling machine.




http://www.thermshield.com/Thermshie...s_Aluminum.pdf
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Last edited by Bksabath; 28th August 2011 at 12:28 AM.
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