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Old 11th February 2012, 03:12 PM   #5311
Salas is online now Salas  Greece
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Quote:
Originally Posted by Joachim Gerhard View Post
Salas published a simple way to measure Hfe and Ft in BJTs.
Its from a MILSPEC document for spot checking. The $ure curve way is:
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Old 11th February 2012, 03:42 PM   #5312
ungie is offline ungie  Canada
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Quote:
Originally Posted by Joachim Gerhard View Post
They are RIFA PPS SMD. I find them one of the most "invisible" caps i heard. You can by them from Distrelec.
Hesener prepares a BOB and instructions but we have to wait for the Beta builds.
There may be also a change in layout. That has to do with grounding. This phono is damn fast. Without the RIAA is would easy go the 100MHz.
Thank you Joachim.
Mouser and Digikey carry Panasonic ECHU PPS capacitors in 2%, but 50V maximum. I have not been able to find a "good" Rifa source in North America, although Mouser does carry some of their products. I'm going to put together a preliminary BOM for my own use to start sourcing and pricing parts. Given that the current source transistors don't likely need to be matched, do you think 100 pcs each of BC327-40 and BC337-40 will be sufficient, or are 250 pcs of each a safer bet?
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Old 11th February 2012, 04:43 PM   #5313
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I have no experience with the Panasonic. What i know is that the material was invented in Japan. It is a substitute for Polycarbonate in so far that is has a very stable temperature coefficient ( for use in cars ? ).It has a little bit more DA then PP though. It is very low distortion ( Bateman at.all. ). Do you remember the pink Roederstein MKC1862
They where used in early Mark Levinson equipment. When you can find them, try them.
They sound very dynamic. This was a Polycarbonate cap.
Pansonic is a quality supplier so i expect good results.
Wima makes PPS SMD caps that look similar.
I would buy 200 each of the BCs. They are inexpensive. Frans finds them so good that he is even substituting 2SA and 2SC types.
Concerning matching i do not think that fanatic selection is required. I usually go for better the 10%. To get enough 5% pairs is easy. Use the ones with the highest Hfe in the input stage.
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Old 11th February 2012, 04:47 PM   #5314
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Here are the Wimas :
WIMA SMD-PPS Kondensatoren
Salas, thanks. When it gets into the extraordinary it gets expensive.
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Old 11th February 2012, 04:52 PM   #5315
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Vishay bought Roederstein and this is a data sheet from 2003.
Maybe they make them again. Have not seen any new ones though.
I have some NOS.
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File Type: pdf MKC1862.pdf (46.7 KB, 26 views)
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Old 11th February 2012, 05:03 PM   #5316
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Here is my little MKC collection. They also came in green. Philips made blue ones.
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Old 11th February 2012, 05:33 PM   #5317
tvi is offline tvi  Australia
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I believe the Evox-Rifa pps caps are sold under the Kemet name in the US.
SMC 682
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Old 11th February 2012, 05:36 PM   #5318
tvi is offline tvi  Australia
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wima Polycarbonate
Quote:
After the discontinuation of Polycarbonate film (end of 2000) as a capacitor dielectric by the only manufacturer, Bayer AG/Germany, we have removed all MKC ranges (metallized capacitors) and FKC ranges (film and foil construction) using this capacitor film from our range of products latest after inventory of film has run out.
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Old 11th February 2012, 07:01 PM   #5319
ungie is offline ungie  Canada
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For the servo, do we want LT1001C or LT1001AM? AM version has lower input offset and bias current.
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Old 11th February 2012, 07:02 PM   #5320
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I would use LF411, OPA134, AD825 in that order.
The LT1001 is quite old.
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