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Re: [Amps] Using surface-mount devices

To: amps@contesting.com
Subject: Re: [Amps] Using surface-mount devices
From: "Dr. David Kirkby" <drkirkby@ntlworld.com>
Date: Sat, 13 Sep 2003 12:52:30 +0100
List-post: <mailto:amps@contesting.com>
Chris Bartram wrote:

> If you have the right tools, it's not so difficult to work with SM discrete
> components down to 0603. 0402 parts are a bit of a pain, but even they can
> be soldered by hand with care. Normal packages down to 0.25mm lead spacing
> don't represent a problem if the PCB is well designed. 

and professionally made. Perhaps you have better techniques than me
Chris, but I would only ever get a board professionally made for those
dimension. Gone are the days of laying out the board with tape, exposing
it to UV and etching it yourself. Perhaps parents of tomorrow won't get
so frustrated as mine did when the inevitable bit of ferric chloride
managed to stain somewhere!! 

It must be said though that for 2-sided boards, if you don't mind
waiting a week, getting them professionally made is not that expensive. 

The other point of mine was about solders. As you are probably aware,
lead is to be banned in solders - at least is Europe. My suspicion is
that this will make hand assembly more difficult. 

Children will have a harder time trying to build circuits than what I
did as a child, where it was relatively easy to find a circuit in
practical Wireless, buy the bits from Maplin, etch your own board with a
UV box and with a bit of luck it worked. (For what it is worth, I'm aged
39, so you can put that is some context). 

I still recall the day I bought my first GaAs FET as a 14-year old with
about 4-weeks money from my Saturday job. I directly earthed myself to
the kitchen sink (something I now know to be quite dangerous for me), so
as to not destroy the FET. It was I guess quite exiting at the time. So
when I left school there was only one thing I thought about - doing a
degree in electrical and electronic engineering. 

I may be being unduly pessimistic, but I can't help feeling the move to
smaller and smaller packages will mean less children build circuits, so
there will be fewer interested in becoming hams. Fewer of those hams
will be able to build anything without very considerable expense.....and
so on. 

I agree with Peter's points about it becoming more difficult
professionally, I agree with yours too, in that is is possible to do
in-house construction. I still maintain my original point that it will
be harder for hams to build their own kit - probably sufficiently harder
to make fewer try. 

I recall many years ago moaning to a ham in the USA about the content of
the RSGB's journal Radcom. I'd tried to get a couple of things
published, both of which were turned down for being too technical. One
was eventually published in QEX. 
http://www.medphys.ucl.ac.uk/~davek/ham/txline.pdf
He felt QST was even worst, saying a typical circuit was "Build yourself
a 12 V 1 A power supplying using a 7812 voltage regulator". It was a bit
tongue-in-cheek of him of course, but that does seem to be the way
amateur radio is going. 

-- 
The day Microsoft makes something that doesn't suck is probably the day
they start making vacuum cleaners." -Ernst Jan Plugge.

Dr. David Kirkby,
Senior Research Fellow,
Department of Medical Physics,
University College London,
11-20 Capper St, London, WC1E 6JA.
Website: http://www.medphys.ucl.ac.uk/~davek
Author of 'atlc' http://atlc.sourceforge.net/
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