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National PF5301 cross reference

J

JW

Jan 1, 1970
0
Looking for a suitable cross-reference for a National PF5301 TO-92 N
channel JFET as I can't find the original part anywhere. Hell, I can't
even find an original datasheet. The critical parameter for the sub is
Igss which for the National part is 1pA. The only thing I've been able to
find so far is a Linear Systems LS5301 which has a Ig of 1pA, but at $40 a
pop (!), I'd like to find an alternate.

Does anyone know of any possible substitutes?

Thanks.
 
J

JW

Jan 1, 1970
0
J

JW

Jan 1, 1970
0
<http://www.datasheetarchive.com/2--PF5301-2-datasheet.html>
Not exactly a data sheet, but it does have some specs. There should
be some other acceptable devices in the chart. 2N4117A or 2N4118 look
very close.

ITYM PN4117A and PN4118A. [Google] Or maybe so?

Those do look good and there seems to be some out there, but I'm not too
crazy about sources that ask for a RFQ only to tell you that they have a
$100 minimum. Was hoping for something I could buy at Digikey or Mouser or
some other distributor with no minimums.

Although there is a Vishay 2N4117A-E3
http://www.mouser.com/ProductDetail...sGAEpiMZZMv4z0HnGdrLjmW9PdigBgHUXen39y4wHUM=I
I wonder what the -E3 means? I found a datasheet, but it does not state
what -E3 is.

Vishay also has a 2N4118A.
http://www.mouser.com/ProductDetail...=sGAEpiMZZMv4z0HnGdrLjmibscKjQIlodZHJqghFYzA=
In stock too. Maybe I'll give that one a go, wrong package but beggars
can't be choosers.

A pity that these are all EOL. *sigh*

Thanks, Jeff.
 
W

William Sommerwerck

Jan 1, 1970
0
What's the application? Do you really need a jfet?

I'm pretty sure I do, as it looks to be a fairly sensitive circuit. It's
for a repair on a Keithley 220 programmable current source.
http://www.google.com/url?sa=t&rct=...k4GgCQ&usg=AFQjCNHiyEb7xQJn29nTeEEYYk4sluspuA

The schematic is on page 6-31/6-32 (4 pages from the end) location Q302
near the top of the page. It's part of circuit which uses a AD515K
FET-Input Electrometer Op-amp.

Hmmm... Would that -- or a similar -- op-amp be suitable?
 
R

Reinhard Zwirner

Jan 1, 1970
0
JW said:
Looking for a suitable cross-reference for a National PF5301 TO-92 N
channel JFET as I can't find the original part anywhere. Hell, I can't
even find an original datasheet. ...

Hi,

I could send you photos (don't have access to a scanner till Monday):
interested? If yes, just contact me per PM.

CU

Reinhard
 
O

o pere o

Jan 1, 1970
0
Yikes, it's a jfet darlington! Really a weird circuit, overall.

I bet a 2N7000 would work. It's just an AC amplifier. Gate currents on a 2N7000
are femtoamps. You can turn one halfway on and leave the gate open, and it will
stay halfway on for hours. Fun to play with.

Did you get the fA figure by measurements? The Onsemi and the Fairchild
give 10 nA as the leakage value. Guess they are much better than
specified...

Pere
 
J

Joerg

Jan 1, 1970
0
JW said:
Looking for a suitable cross-reference for a National PF5301 TO-92 N
channel JFET as I can't find the original part anywhere. Hell, I can't
even find an original datasheet. The critical parameter for the sub is
Igss which for the National part is 1pA. The only thing I've been able to
find so far is a Linear Systems LS5301 which has a Ig of 1pA, but at $40 a
pop (!), I'd like to find an alternate.

Does anyone know of any possible substitutes?

Thanks.


How about this?

http://www.trendsetter.com/v/vspfil...grated Systems/SST440, SST441, U440, U441.pdf

Around $8 but there's two in the package.
 
J

John Devereux

Jan 1, 1970
0
o pere o said:
Did you get the fA figure by measurements? The Onsemi and the
Fairchild give 10 nA as the leakage value. Guess they are much better
than specified...

I expect they can't be bothered to test them; it would take too long to
resolve fA I think. But 10nA is huge.

[...]
 
J

Jasen Betts

Jan 1, 1970
0
Found it. National NDF9401 through NDF9410 monolithic JFET cascodes.
The text of the National 1977 FET databook is on archive.org (no images
unfortunately).

Hmm, JFET, so depletion; it was probably like this.

|
|
|--'
|
.--->|--.
| |
| |
| |--'
| |
----|--->|--.
| |
`-------+
|
|

JFET cascode
 
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