JFET with fwd xfer admittance >30mmhos?

J

Joerg

Guest
Just curious, ran into this a few times: Is there a JFET in the J310
price category with a forward transfer admittance in excess of 30mmhos?
Doesn't matter whether N or P.

The BF862 fits the bill very nicely at 45mmhos but it costs around 15c,
versus 6c or so for the J310. Looking for a partially free lunch here
.... :)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Just curious, ran into this a few times: Is there a JFET in the J310
price category with a forward transfer admittance in excess of 30mmhos?
Doesn't matter whether N or P.

The BF862 fits the bill very nicely at 45mmhos but it costs around 15c,
versus 6c or so for the J310. Looking for a partially free lunch here
... :)
Click to expand...
Although the 2N4391 switch was never speced for gfs, which is what I
hope you're refering to on an older datasheet, MPS4391 developed for
the same purpose was 20mS typ. Might be worth looking at the MMBF4391
switches, for function.

I only recall one or two that were higher (BSV39 70mS typ) without
actually being a high power device (U244 U266), though Teledyne ($)
did quite a few above 20mS (2N6453).

RL
 
legg wrote:
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Just curious, ran into this a few times: Is there a JFET in the J310
price category with a forward transfer admittance in excess of 30mmhos?
Doesn't matter whether N or P.

The BF862 fits the bill very nicely at 45mmhos but it costs around 15c,
versus 6c or so for the J310. Looking for a partially free lunch here
... :)

Although the 2N4391 switch was never speced for gfs, which is what I
hope you're refering to on an older datasheet, MPS4391 developed for
the same purpose was 20mS typ. Might be worth looking at the MMBF4391
switches, for function.

I only recall one or two that were higher (BSV39 70mS typ) without
actually being a high power device (U244 U266), though Teledyne ($)
did quite a few above 20mS (2N6453).
Click to expand...
They have all gone to lalaland. The MMBF4391 is still made by ON and
Fairchild but hard to get. And it's still <20mmhos.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
On Fri, 18 Jul 2008 08:03:56 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

spin


They have all gone to lalaland. The MMBF4391 is still made by ON and
Fairchild but hard to get. And it's still <20mmhos.
Click to expand...
Did you confirm the gfs of an xx4391 sample? I see that the ON
datasheet shows it still climbing at 30mA, with the minimum Idss for
the part exceeding 50mA. Same might be said for the MMBFJ310, although
its minimum Idss is half that. Just curious.

Is it intended to work at VHF, or is this just an incidental
characteristic of the BF862?

Should have thought, that with cost being important, the .104 price
might have justified the effort. This would likely change, on serious
inquiry, for a multiply-sourced part that hasn't recently been
ordered. (BF862 is .16 from the same vendor's single source). The
PMBFJ310 is .095 from the same vendor, for reference.

RL
 
legg wrote:
On Fri, 18 Jul 2008 08:03:56 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

spin
They have all gone to lalaland. The MMBF4391 is still made by ON and
Fairchild but hard to get. And it's still <20mmhos.

Did you confirm the gfs of an xx4391 sample? I see that the ON
datasheet shows it still climbing at 30mA, with the minimum Idss for
the part exceeding 50mA. Same might be said for the MMBFJ310, although
its minimum Idss is half that. Just curious.
Click to expand...
I haven't, don't have one here. But in an oscillator scenario it would
become quite toasty and you'd have to load it down at the output.


Is it intended to work at VHF, or is this just an incidental
characteristic of the BF862?
Click to expand...
Most of them are like that. For me it rarely matters, you just have to
make sure they don't "sing" up there. Else the FCC sends the goons out ;-)


Should have thought, that with cost being important, the .104 price
might have justified the effort. This would likely change, on serious
inquiry, for a multiply-sourced part that hasn't recently been
ordered. (BF862 is .16 from the same vendor's single source). The
PMBFJ310 is .095 from the same vendor, for reference.
Click to expand...
Digikey? There they'll go to around 7c for 50k or larger qties.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
On Fri, 18 Jul 2008 14:26:21 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Fri, 18 Jul 2008 08:03:56 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

spin
They have all gone to lalaland. The MMBF4391 is still made by ON and
Fairchild but hard to get. And it's still <20mmhos.

Did you confirm the gfs of an xx4391 sample? I see that the ON
datasheet shows it still climbing at 30mA, with the minimum Idss for
the part exceeding 50mA. Same might be said for the MMBFJ310, although
its minimum Idss is half that. Just curious.


I haven't, don't have one here. But in an oscillator scenario it would
become quite toasty and you'd have to load it down at the output.


Is it intended to work at VHF, or is this just an incidental
characteristic of the BF862?


Most of them are like that. For me it rarely matters, you just have to
make sure they don't "sing" up there. Else the FCC sends the goons out ;-)


Should have thought, that with cost being important, the .104 price
might have justified the effort. This would likely change, on serious
inquiry, for a multiply-sourced part that hasn't recently been
ordered. (BF862 is .16 from the same vendor's single source). The
PMBFJ310 is .095 from the same vendor, for reference.


Digikey? There they'll go to around 7c for 50k or larger qties.
Click to expand...
Belatedly, try 2SK536 from Sanyo, if you can find a distributor.

RL
 
legg wrote:
On Fri, 18 Jul 2008 14:26:21 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Fri, 18 Jul 2008 08:03:56 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

spin
They have all gone to lalaland. The MMBF4391 is still made by ON and
Fairchild but hard to get. And it's still <20mmhos.
Did you confirm the gfs of an xx4391 sample? I see that the ON
datasheet shows it still climbing at 30mA, with the minimum Idss for
the part exceeding 50mA. Same might be said for the MMBFJ310, although
its minimum Idss is half that. Just curious.

I haven't, don't have one here. But in an oscillator scenario it would
become quite toasty and you'd have to load it down at the output.


Is it intended to work at VHF, or is this just an incidental
characteristic of the BF862?

Most of them are like that. For me it rarely matters, you just have to
make sure they don't "sing" up there. Else the FCC sends the goons out ;-)


Should have thought, that with cost being important, the .104 price
might have justified the effort. This would likely change, on serious
inquiry, for a multiply-sourced part that hasn't recently been
ordered. (BF862 is .16 from the same vendor's single source). The
PMBFJ310 is .095 from the same vendor, for reference.

Digikey? There they'll go to around 7c for 50k or larger qties.

Belatedly, try 2SK536 from Sanyo, if you can find a distributor.
Click to expand...
There are a few mouth-watering JFETs from Japan but many of them have
become boutique parts. My clients would have me flogged :)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
On Fri, 08 Aug 2008 08:27:37 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Fri, 18 Jul 2008 14:26:21 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Fri, 18 Jul 2008 08:03:56 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

spin
They have all gone to lalaland. The MMBF4391 is still made by ON and
Fairchild but hard to get. And it's still <20mmhos.
Did you confirm the gfs of an xx4391 sample? I see that the ON
datasheet shows it still climbing at 30mA, with the minimum Idss for
the part exceeding 50mA. Same might be said for the MMBFJ310, although
its minimum Idss is half that. Just curious.

I haven't, don't have one here. But in an oscillator scenario it would
become quite toasty and you'd have to load it down at the output.


Is it intended to work at VHF, or is this just an incidental
characteristic of the BF862?

Most of them are like that. For me it rarely matters, you just have to
make sure they don't "sing" up there. Else the FCC sends the goons out ;-)


Should have thought, that with cost being important, the .104 price
might have justified the effort. This would likely change, on serious
inquiry, for a multiply-sourced part that hasn't recently been
ordered. (BF862 is .16 from the same vendor's single source). The
PMBFJ310 is .095 from the same vendor, for reference.

Digikey? There they'll go to around 7c for 50k or larger qties.

Belatedly, try 2SK536 from Sanyo, if you can find a distributor.


There are a few mouth-watering JFETs from Japan but many of them have
become boutique parts. My clients would have me flogged :)
Click to expand...
This isn't one of them, but you have to buy them new through a Sanyo
rep. They've been in production long enough to be available in smaller
quantities from brokers.

On closer inspection, it's also not a JFET, but NMOS.

RL
 
legg wrote:
On Fri, 08 Aug 2008 08:27:37 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Fri, 18 Jul 2008 14:26:21 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Fri, 18 Jul 2008 08:03:56 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

legg wrote:
On Thu, 17 Jul 2008 15:24:48 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

spin
They have all gone to lalaland. The MMBF4391 is still made by ON and
Fairchild but hard to get. And it's still <20mmhos.
Did you confirm the gfs of an xx4391 sample? I see that the ON
datasheet shows it still climbing at 30mA, with the minimum Idss for
the part exceeding 50mA. Same might be said for the MMBFJ310, although
its minimum Idss is half that. Just curious.

I haven't, don't have one here. But in an oscillator scenario it would
become quite toasty and you'd have to load it down at the output.


Is it intended to work at VHF, or is this just an incidental
characteristic of the BF862?

Most of them are like that. For me it rarely matters, you just have to
make sure they don't "sing" up there. Else the FCC sends the goons out ;-)


Should have thought, that with cost being important, the .104 price
might have justified the effort. This would likely change, on serious
inquiry, for a multiply-sourced part that hasn't recently been
ordered. (BF862 is .16 from the same vendor's single source). The
PMBFJ310 is .095 from the same vendor, for reference.

Digikey? There they'll go to around 7c for 50k or larger qties.
Belatedly, try 2SK536 from Sanyo, if you can find a distributor.

There are a few mouth-watering JFETs from Japan but many of them have
become boutique parts. My clients would have me flogged :)

This isn't one of them, but you have to buy them new through a Sanyo
rep. They've been in production long enough to be available in smaller
quantities from brokers.

On closer inspection, it's also not a JFET, but NMOS.
Click to expand...
That wouldn't work in really low voltage envoironments. Often one needs
a JFET that can reliably start and deliver some juice as an oscillator
at a few hundred millivolts.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
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