On Tue, 15 Feb 2005 08:18:47 -0000, "Airy R.Bean"
wrote:

But what of the "liebebstraum" (sp?) for future experimentation
with the circuitry?


Hate top posting, you always loose the question.

Since I do experiment and modify I allow for it. I enjoy building
small. Since many of my designs are elaborate I've gotten used to
working in small spaces and laying out circuits for accessability and
considerations for possible future changes.

Sometimes I will work around an existing package. I have a number of
of old computer serial A/B switches. They are aluminum with a rounded
side top and bottom shell. The front and rear plate form a simple
frame to screw the case into one unit. It's a trivial task to make
replacement front and rear as the original have too many holes. I got
these for free when a local merchant decided they were of
insufficient value to store for sale.

My latest project is a 5Wpep SSB tranceiver for 6M band in a package
thats only 2x5x7 inches with PLL tuning and digital display. The pll
module is only 1.5"x1.5"x1" constructed dead bug on pcb material
which also forms the case/shield. It could be made smaller but,
that was adaquately small for this project. The power amp is three
transistors of VHF types and fits in a strip of 1.25"Wx 2.5"L x1.5H
excluding heatsink(case is aluminum). For 10mW in I get 5W pep
with good IMD. The front end (rf amp, mixer and mixer amp ) is
complete [1x1x1..25"] and is both compact and very low noise.
The bandpass filter assembly and the crystal filter IF amp sections
are done too. The rest will easily fit in that box obviously.

When doing this I have to consider mechanical things like connectors,
controls and other parts that may be physically large compared to the
circuits they control. For example the froont pannel has to to have
a volume control, RF gain, tuning , microphone jack, headphone jack,
frequency display and meter for RX signal and tx power all in 2x5
inches. The RF gain and volume will have to be a dual (coaxial)
control to fit it all. As you can see getting all the knobs in place
can be more difficult than the electronics behind it.

The only components that will not be in the box will be microphone
dattery and antenna. I exclude the antenna (portable 3 element beam)
and battery power as this is an excusion radio. A 10AH battery of the
gell electrolyte type will be adaquate for a 24 hour field use.

Small is not hard and doesn't contradict high perfomance.

Allison
KB1GMX