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THE AM BULLETIN BOARD => QSO => Topic started by: Ed/KB1HYS on November 07, 2011, 07:33:45 PM



Title: Oh No!
Post by: Ed/KB1HYS on November 07, 2011, 07:33:45 PM
While flipping through one of my favorite parts websites, I discovered that several formerly ubiquitous parts where slated for "obsolescence" with a big "End of Life" notice on their entries. 

MPF102 FETs,  2N23904, and 2N3906 in the through hole packages and other similar discrete transistors mostly. 

Damn, I was just getting into solid state stuff.    Think there'll be NOS JFETs in a few years?


Title: Re: Oh No!
Post by: WA1GFZ on November 07, 2011, 10:03:26 PM
they come in surface mount packages


Title: Re: Oh No!
Post by: N4LTA on November 07, 2011, 10:18:34 PM
They are dirt cheap - buy a hundred of each and you will have plenty.

I'd buy j310s instead of the mpf102


Title: Re: Oh No!
Post by: Opcom on November 08, 2011, 01:15:35 AM
Time for sockets for SMT parts. Some exist for costly or special packages that the part fits in and is clamped down.

Just be happy that there are SMT parts large enough to be seen and handled with small hand tools.


Title: Re: Oh No!
Post by: Ed/KB1HYS on November 08, 2011, 06:36:10 AM
Very hard to experiment with SMT stuff. well at least for me anyway.  I haven't seen a breadboard yet that will work with SMT, let alone "ugly-bug" construction.   I am going for a "life-time" buy of some of the more common stuff in leaded cases.  Like you said, 100 each or so is still really cheap.


Title: Re: Oh No!
Post by: N4LTA on November 08, 2011, 09:24:34 AM
I just finished a PC Board for an AM detector that is all smt. The detector has .025" pitch leads and is tiny.
The board has a smt 78L05 regulator and the detector IC is about 1/4 the size of the smt 78L05. The board measures roughly 1/2"' x 1.25".

I usually coat my boards with tin using Liquid Tin but after a few days, they do not solder to as well as bare, clean copper. I am scratching my head as to what to do with this board. Thinking about putting a coat of solder cream on the whole board and solder coating it , then cleaning it before trying to mount the smt parts.

My eyes are getting worse and this stuff will not get larger. I just bought a cheap stereo microscope.

There won't be any sockets for devices other than large CPUs etc. Forget about sockets for discrete devices.


Title: Re: Oh No!
Post by: KM1H on November 09, 2011, 07:31:09 PM
SMT is fun, I even have the requisite B&S microscope, proper soldering gear, hot plate and other stuff to play up above where the air is thin and wavelengths are in fractions of inches.

I let others make the PC boards ::)


Title: Re: Oh No!
Post by: W1IA on November 09, 2011, 08:01:29 PM
While flipping through one of my favorite parts websites, I discovered that several formerly ubiquitous parts where slated for "obsolescence" with a big "End of Life" notice on their entries. 

MPF102 FETs,  2N23904, and 2N3906 in the through hole packages and other similar discrete transistors mostly. 

Damn, I was just getting into solid state stuff.    Think there'll be NOS JFETs in a few years?
Tnxs for the heads up Ed.....I use those parts in tons of projects...need to stock up b4 they become un-obtainium. I have no desire to deal with SMT


Title: Re: Oh No!
Post by: N4LTA on November 10, 2011, 10:01:46 AM
Yes, thanks again for the heads up.

I got 100 of MPF102 and 3906 and 200 3904s yesterday from Newark. They were cheap - less than $20 for all. Newark's distribution center is 20 miles away in Gafney and they give great service. If I order by 10 PM - I get the package on the doorstep by 2pm the next day via UPS ground.

I used to order exclusively from Mouser and DigiKey but Newarks prices are nearly as good and it is hard to turn down that kind of delivery.

After checking, I already had 100 J310s


Title: Re: Oh No!
Post by: NE4AM on November 17, 2011, 01:52:59 PM
Double check this info - A lot of parts being obsoleted are the non-RoHS parts with lead-solder tinned leads.  They are being replaced by otherwise-identical 'unleaded' equivalents. 

73 Dave


Title: Re: Oh No!
Post by: W1RKW on November 17, 2011, 04:06:04 PM
Double check this info - A lot of parts being obsoleted are the non-RoHS parts with lead-solder tinned leads.  They are being replaced by otherwise-identical 'unleaded' equivalents.  

73 Dave

A rumor about tin/lead solder being phased out for lead free solder made me buy a life time supply of 60/40.  I wonder how RoHS parts work with non-RoHS solder and vice-versa.


Title: Re: Oh No!
Post by: Ed/KB1HYS on November 17, 2011, 04:16:21 PM
We have that problem at work. We need Lead based solder for reliability, but can only get RoHS non-lead tinned parts.  We just tin them with leaded solder.  It doesn't take much lead to prevent Tin wiskers so the tinning process work fine.  I imagine it would be the same with any components used, not just SMT.


Title: Re: Oh No!
Post by: WA1GFZ on November 17, 2011, 04:43:36 PM
Mil stuff still doing lead


Title: Re: Oh No!
Post by: W1RKW on November 17, 2011, 05:09:08 PM
Yeah, we're still using lead here at the boat, thankfully.  The defense secretary was here today giving an ambiguous speech to the ship yard.  We'll see where all the lead ends up.
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