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Old 3rd June 2008, 01:31 AM   #6001
dimitri is offline dimitri  United States
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Quote:
I've recently seen a paper of a guy who read out SQUIDs with a single Infineon SiGe BFP650 at cryo temp.
Did this with Si JFET @ 10-12K 15 years ago. Good old days...
 
Old 3rd June 2008, 02:02 AM   #6002
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'Kickin' the gong around.'
 
Old 3rd June 2008, 02:05 AM   #6003
KSTR is offline KSTR  Germany
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Quote:
Originally posted by gerhard
Since you are in Berlin, you really should know better:

http://www.siemens-stadt.de/siemroe0.htm

3 years ago, I still saw guideposts there in Siemensstadt.
I think they still make microwave TWTs
Yeah, sorry, I mixed this up with the notion that Siemens apparantly never made a EL34, that was my point. Other tubes than EL34's they used to make of course, in their own fab (I have a bunch of E83CC's in a drawer).

BTW, @John, did you receive my PM?

- Klaus
 
Old 3rd June 2008, 02:10 AM   #6004
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Quote:
Originally posted by Terry Demol
Speaking of interfet, don't they do sk170 / sj74 replacements?
No, that's Linear Systems. But they only have the 170 replacement. They've been promising the 74 for at least a couple of years now but so far haven't delivered.

se
 
Old 3rd June 2008, 02:33 AM   #6005
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>I have used IRF610 and 9610 types
>as input devices for power amps and
>as the only devices in some line stage
>circuits, and while nobody complained,
>they clearly are way noisy compared to
>good JFETs or Bipolars.

OK ..... Would you please compare IRF610
to it's higher power equivalent ... I.E.
Mosfet with same breakdown voltage,
threshold voltage, more gm and higher
power rating (current capability) , noisewise ?
Just to make a perhaps an impracticle point ?
Dare to be even greater !
 
Old 3rd June 2008, 02:49 AM   #6006
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Not a good direction to go.
 
Old 3rd June 2008, 03:31 AM   #6007
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just to prove the point that power mosfets are
actually the sum of a bunch of small signal mosfets
no practicle knowledge gained
just for the basic insight
 
Old 3rd June 2008, 06:22 AM   #6008
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Low noise jfets are paralleled also. That is why they are called Meshfets. Please, you are wasting time and space.
 
Old 3rd June 2008, 07:41 AM   #6009
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PMA -

my experience is that a small RC-filter on the input with superb passive components does not affect sonics. With small I mean 50-100 Ohms and 10-100pF, and with superb passives I mean film&foil type PS and or PP caps.



Sigurd

Quote:
Originally posted by PMA
I mean the capacitor influence on sound, and possible benefit of RF reduction vs. capacitor problem - I asked for no trivial answers, Upupa.

P.S.: Any lower rate college student could answer me about phase response, it is not helpful. I am asking for experience in this field.
 
Old 3rd June 2008, 07:57 AM   #6010
PMA is offline PMA  Europe
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Sigurd,

I hope you do not mean polyester (mylar), when you write PS.
 

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