I believe the old Clifton Labs pages had some nice info on JFET parameters.
Can't get to anymore?
W7ZOI has a nice page on measuring IDSS which I recall to be the parameter
on the spec sheet most relevant: http://w7zoi.net/jfet101.pdf
Measuring IDSS only takes a 10V power supply and a milliameter, very easy.
I bought a good stock of TO92 J310's before they were obsoleted. The SMD
parts are still super available and easy to attach flying leads to (usually
you'll tack the gate down to ground anyway leaving two flying leads.)
Tim N3QE
On Mon, Jul 2, 2018 at 3:25 AM, Martin Kratoska <martin@ok1rr.com> wrote:
> Lee,
>
> very interesting. Many thanks for that valuable info! BTW is there any
> easy, cheap and quick method to test the J310, possibly without need of
> dedicated complex 'test jig'?
>
> 73,
> Martin, OK1RR
>
>
> Dne 2.7.2018 v 02:39 Lee STRAHAN napsal(a):
>
> Thanks Tony,
>> Agreed the 2N5109 will be around for a long time however as you point
>> out they are or will be very expensive. At present I use 100's of 2N3866
>> transistors which are very close to the same die if not selected from the
>> 2N5109 process. My cost in 100 quantity has gone from about $1.60 each to
>> currently $4.00 each in about 2 years' time for 2N3866's. The 5109 is
>> currently priced less at $2.22 where the 3866 used to be less. From all
>> this I conclude that the 2N5109 will follow the huge price increases. I
>> could be wrong but I will not plan on using the 5109 especially where most
>> things are going to surface mount also. Even J-310 FETs have gone from
>> <$.20 to $2.41 at 100 level. Worst thing is 20% of the off brand j-310s
>> don’t meet spec. The only way to solve this is to go to surface mount where
>> you can still get the good J-310 and other great devices. One can often use
>> more than one SMD device in an amplifier having it cost less than one
>> expensive leaded device. For the hams building a single amplifier the 5109
>> makes a lot of sense right now. Semiconductor times are changing rapidly. I
>> make lots of top-band antenna systems using lots of already expensive
>> electronics. For this reason I have to do as well as I can to predict the
>> future for my products. My observation is that leaded parts are
>> disappearing rapidly and this will continue.
>>
>> Lee K7TJR
>> Hi-Z Antennas
>>
>> -----Original Message-----
>> From: N2TK, Tony <tony.kaz@verizon.net>
>> Sent: Sunday, July 1, 2018 2:03 PM
>>
>> To: 'Lee STRAHAN' <k7tjr@msn.com>; martin@ok1rr.com;
>> topband@contesting.com
>> Subject: RE: Topband: Any experience with 2N3553?
>>
>> The 2N5109 will be around for many years. It is widely used in the
>> military and space community. It is listed as a JAN part. But it ain't
>> cheap.
>> 73,
>> N2TK, Tony
>>
>> -----Original Message-----
>> From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Lee
>> STRAHAN
>> Sent: Sunday, July 01, 2018 2:15 PM
>> To: martin@ok1rr.com; topband@contesting.com
>> Subject: Re: Topband: Any experience with 2N3553?
>>
>> Hello Martin and all,
>> The 2N3553 device was plagued with a low Ft (high at its
>> introduction) making it mostly a low frequency device with questionable
>> high gain high frequency use in typical ham preamps. It is no longer
>> available through the original manufacturers. Also perhaps you are thinking
>> of the BFQ18A and not the BFQ19A device. The BFQ19 is at end of its life
>> cycle and in addition the 18A is widely used now in the MATV industry for
>> wideband amplifiers. I have some experience with the 18A using it in a
>> wideband Norton style amplifier where it is providing 10+dB of gain with a
>> measured noise figure of 2 dB on 160 meters. Its typical IMD is at least
>> listed at UHF on the data sheet. My IMD testing setup is not adequate to
>> test the range of this device but I can say that it exceeds any other
>> amplifiers I have built to date. I typically use the 2N3866 which
>> unfortunately is pricing itself out of the market now. I suspect the 2N5109
>> will follow as inventories shrink.. A pair of the 18A devices at ~$1.00 USD
>> each single price in a push pull Norton configuration would in my opinion
>> make it worth trying as a killer wideband amp.
>> Just my $.02 USD.
>> Lee K7TJR OR
>>
>> -----Original Message-----
>> From: Topband <topband-bounces@contesting.com> On Behalf Of Martin
>> Kratoska
>> Sent: Sunday, July 1, 2018 9:51 AM
>> To: topband@contesting.com
>> Subject: Topband: Any experience with 2N3553?
>>
>> The 2N3553 is a brutal 7 watt device in a TO-39 metal package. Chris
>> Trask, N7ZMY mentioned some unparalleled IM characterics
>>
>> '... The BFQ19 (made by NXP née Philips) and the NE46134 (made by NEC)
>> are both highly popular within the CATV industry, and are virtually
>> identical in terms of linearity. They compare favorably to the 2N5109 in
>> terms of linearity, though they pale in camparison with the 2N3553 (as do
>> all the others)...'.
>>
>> See
>> http://www.home.earthlink.net/~christrask/Bipolar%20Transist
>> or%20Evaluation.pdf
>>
>> 2N3553 is often mentioned in transmitting applications but I was unable
>> to find some other details like IM, noise and gain characteristics in high
>> DR preamps for receiving purposes. Any experience?
>>
>> 73,
>> Martin, OK1RR
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