Ian White GM3SEK wrote:
Jim Barber wrote:
I've been working on a high-power HF autotuner design that I'd just
about shelved because of the necessity of soldering the DDS chip. (it
uses an internal RF source to power the phase detector)

This thread has helped a lot. When time permits I may order up some
parts and give it a try. I have a good-quality magnifier lamp and a
fine-point temp-controlled pencil, what I don't have is OEM eye lenses
and flexible finger joints... ;-)

Most of my SMD work is done using half-moon reading glasses - the
strongest and cheapest available from the drugstore - in front of my
normal glasses. When not in use, they hang from a neck cord.

After publishing this suggestion, a very generous person *gave* me a
professional-quality binocular microscope. This is wonderful for big
jobs like assembling a whole new board... but to be honest, I still tend
to use the double glasses more, because the "setup process" is much
quicker.

You will find that the tip of the soldering iron becomes much steadier
when seen under the magnifier. This feedback loop is a wonderful thing,
especially if you give it the best possible chance to work:

* "Use the scope, Luke!" - learn to concentrate exclusively on what
you're SEEING. This is harder than it seems, because for normal
soldering we also rely a lot on our sense of touch, and automatically
tend to press the tip of the iron against the parts being soldered. With
SMD this is a disaster - it simply pushes the parts out of position - so
you need to break that habit and concentrate on using ONLY your eyes.

The problem with a 10x microscope is first FINDING the soldering iron
tip in the field of view. If I am looking into the microscope and
trying to place the iron on the work often the iron ends up way in left
field (or I push it into my other hand OUCH!) TOO much magnification
can be TOO much of a good thing. I wish I had another set of eye piece
lenses (or an other objective) so I could go down to 5X sometimes.

My microscope is a true binocular with poro prisms and dual objective
and eyepiece lenses. It was a 'gift' from a former employer (they were
cleaning up the lab and threw it out). I did have to jury rig a stand
since only the optic head was found in the trash, the unit originally
mounted on a long spring loaded 'gooseneek', like those circleline
magnifier lamps. (One of the focus knobs is cracked in half, but I can
live with that).

* Steady your arm against the edge of the bench, so you're not trying to
stabilize your whole body.

* Stay off the caffeine - it creates a fine tremor that the brain cannot
stabilize (too much "noise" in the feedback loop).



Damn Cuban Coffee (Well, I work in Miami!)