The mechanical filters Collins has supplied for amateur radio equipment
are very poor in static. I'm going to gaussian or bessel in my next home
built radio.
The mechanical and lattice crystal filters use a Tchebychev response
curve that does more than a little convolution of pulses to ringing. The
Tchebychev time response converts a click to a craaaaash. Its still a
click in my TT filter even with extra poles of cascaded filters.
Rosin based fluxes often are not cleaned, but I've found that with CMOS
circuitry they do need to be cleaned to prevent circuit failures in high
humidity conditions from excess leakage. A fault that can't be found in
the air conditioned factory service shop.
With anti lead biases around the world, soon it will be international
law that one must use only lead free solder for all electronics. Parts
of the EC and some Asian factories have already converted.
It is often useful to use copper or silver bearing solder with surface
mount components when hand soldering so that the solder doesn't dissolve
the termination from the part.
73, Jerry, K0CQ
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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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