On 02/17/2017 03:55 PM, Benderthe.evilrobot wrote:

"Phil Hobbs" wrote in message
...
On 02/16/2017 12:46 PM, Clifford Heath wrote:
On 17/02/17 09:03, Dave Platt wrote:
I was repairing a piece of old equipment, and needed a replacement RF
transistor. Checking at Digi-Key, I found very thin pickings, so i
checked
a few other distributors, and found the same situation. They seemed
to have
a modest choice of SMT transistors, but REALLY thin variety in
T0-92 and
similar plastic packages. Not a good sign, as we have a lot of 30 -
40 year
old nuclear instrumentation here.

Yup. The last five years or so have been dire times for through-hole
semiconductors. A lot of the popular parts are now gone, past the
end of the "lifetime buy" cycle from their original manufacturers.

I've been trying to stock up my own (hobbyist-level) supplies of
useful TO-92 transistors...

Why? You're not doing production if 100 is lifetime. If it's for
prototyping, why not just learn to prototype in SMT? It's not that
hard. A lot of RF things are easier because stuff is physically
smaller.

SMT prototyping is about a factor of 10 slower than dead bug using
through-hole parts. Every DIP package gets you a bunch of nice strong
standoffs.

I regularly include SMD parts in dead-bug prototypes. With a bit of
thought and planning they can reduce wire links instead of increasing
them, they also tend toward adding rigidity to the assembly.

Sure, me too. I disagree about rigidity though. RN60C resistors are
pretty rigid.

I've recently done a mid-air proto using 0402s--like five in a row in
mid air--but that was a 100-ps sampler, so it was worth the trouble.
Ordinary dead bug is good to 1 GHz or so, and it's a lot easier.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.neth