With so few radio/tv makers in this country practically no distributors
stock "radio" parts, only computer parts.
A couple sunspot minimums ago (at the approach of that minimum), I took
on the design of a pocket radio for Ditto Heads that wanted to listen to
15.420, WRNO afternoons. I looked at Plessey parts, they had some
interesting ones in their catalog, quoted me only 50 weeks delivery of
samples. I took that as a hint that they needed 50 weeks to see if they
really could make what was in the catalog. I found a pocket AM radio at
RS with an interesting Toshiba chip. Called Toshiba US, asked about the
part number, they said, "That's not a valid part number." To which I
reminded them I had one in my hand with that year's date code. Toshiba
didn't sell linear chips in the US, only digital. It was such a good
chip that I experimented with it after getting some data from the
nearest Toshiba rep and then designed it in, going through a broker to
import chips from Japan going around their distributors. I probably
learned more about the chip than everyone at Toshiba other than the
designer. The following sunspot minimum killed the radio and that
shortwave station. But I took my cut as a fixed price design project and
it worked decently when there was any propagation at all, but the fellow
that packaged it took several months of the few remaining working on a
custom case when he should have bought and machined a stock case to save
months on the mold making process. "But with the mold in hand, cases are
almost free!" he said. Yah, after $50K for the molds and the electronic
design only cost $8K. 'Twasn't my money once I got paid.
SMT is the wave and tiny SMT the future. The working parts of
transistors have been tiny for half a century. I was visiting a
transistor line supervisor from TI for supper once, and he noticed a
black thing under his finger nail about the size of a pepper grinding,
but he looked closer and announced it was a transistor die. The packages
even then were just for human handling. Now a chip that size may include
a thousand transistors and be barely visible and with machine assemble
its practical to mount it on a board with others like it so the device
(the radio or thumb drive or ipod) package is empty, but just big enough
to be handled by ordinary hands.
I have used a few SMT parts in the past, but just acquired three SMT
projects. One, a Softrock Lite II for practice, and then a 10 GHz preamp
and an 10 GHz power amp to put on the air. First I have to finish moving
and set up a SMT work station with good magnification and a tiny
soldering iron and in a quiet spot no where near a carpet. I suspect the
classic design of a jeweler's or watch makers bench with side and back
boards to catch flying parts, and a catch rail under the front edge with
a drape to connect that to the pants to catch those parts trying to
escape behind the user could be a handy design, especially for 0402 SMT
parts. The magnification is a Cambridge (copy of Bausch and Lomb)
Stereozoom 7.
Mouser and Digi-Key have been good for some styles of prototyping, I get
parts from the faster than I used to get quotes from Newark, before
Newark and I had a tiff. Some vendors are pretty good about engineering
samples for prototypes and some aren't. The USPS and the brown trucks
are my replacement for the local distributor that dried up, not keeping
parts on hand but saying, "I can order them." To which I said, "I can
order them too, but I would have liked to have had them TODAY, not next
week."
73, Jerry, K0CQ
On 8/9/2010 4:28 PM, Stuart Rohre wrote:
Amen to the supply issues!
That is a moving target on some once common items today. Through hole
parts vs. SMT parts in common and specialized functions for example.
We lost one of our few stocking local distributors a couple months back.
A real pain for small quantity prototyping now.
Stuart
K5KVH
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