Topband: Anyone have a boat load of J-310s?

[Charlie Cunningham]

Jim,

If you really have trouble getting some J-310s, let me know.  I'd really
have to hunt -probably out in my garage. The J-310s that I have, if I could
find them, are, I expect, at least 20 years old and pre-date the shenanigans
that Paul is warning you about. The ones that I had, are, as I recall,
either ON Semi or NSC.  I probably should find mine, I guess.  I bought the
JFET version of the old AMECO preamp, from my friend, Bill, K4CIA, so I
might need some spares someday. The vacuum tube version of the AMECO preamp
didn't have those vulnerabilities, and worked great on all the low bands up
through 30m, for the same purpose that you are using yours for.

Paul's giving you some good advice. That's why I asked if you had tried
Digi-Key.  GL!

73.
Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Paul
Christensen
Sent: Sunday, August 25, 2013 2:44 PM
To: James Rodenkirch; topband at contesting.com
Subject: Re: Topband: Anyone have a boat load of J-310s?

Jim,

The major semiconductor manufacturers (e.g., Fairchild) who once 
mass-produced JFETS in TO-92 style cases have now "obsoleted" most of them. 
This occurred approximately 2-3 years ago.  When shockwaves of the news hit,

many folks (and the on-line bottom feeders), started hoarding the remaining 
supply. Even the SMD versions are now in danger of going obsolete. 
Presently, only InterFET Corporation and Linear Systems appear to be 
manufacturing both through-hole and SMD versions of high-performance JFETs 
although their per-piece prices are very high.  Before the wave hit, I 
purchased hundreds of various JFETs in TO-92 style cases -- J310s being one 
type.  You're welcome a to a few.  True, in many applications it may not 
make a big difference between say a J310 and MPF-102, but it unnerves me 
when I don't know exactly what I'm using in a circuit.

Be careful when sourcing any semiconductor. As you noticed, JFETs are widely

available on the Asian market but when making a purchase through small 
on-line retailers - and the big auction site, it's not possible to trace the

supply chain of the component to its origin.  For example, some Toshiba 
low-noise bipolar transistors are in fact re-labeled 2N3904 devices.  Unless

the purchaser has access to a curve tracer and a means to perform critical 
noise and frequency response testing, one is left to trust the seller for a 
clean "chain of custody" between the time of manufacture and point of sale. 
When China is the only source of many TO-92 JFETs, the red flags are up (no 
pun intended).  Because of this, I have only purchased semiconductors direct

from the OEM or through well-established distributors including Newark, 
Mouser, Digi-Key, Arrow, AvNet, and Allied.  For an interesting perspective 
concerning the severity of the counterfeit semiconductor market, see the 
following report issued by the Semiconductor Industry Association (SIA):

http://tinyurl.com/l9hqpw6

Let me know if you're address is currently good on QRZ.

Paul, W9AC


----- Original Message ----- 
From: "James Rodenkirch" <rodenkirch_llc at msn.com>
To: <topband at contesting.com>
Sent: Sunday, August 25, 2013 9:16 AM
Subject: Topband: Anyone have a boat load of J-310s?


>
> The J-310s in my little preamp are kaput - I looked at Mouser but the 
> shipping costs are way too high for a couple of little Jfets - any body 
> have lots of extra J-310 (or equivalent) they could spare? What ever your 
> costs would be, including mailing them off, would be far cheaper than what

> it would cost me to buy them outright!
>
> Thank you, in advance, for any help -- reply off line works good for 
> me....72, Jim Rodenkirch
>
> _________________
> Topband Reflector 

_________________
Topband Reflector