"Joe" wrote in message link.net...
"Reg Edwards" wrote in message
...
An 18 nano-henry inductor seems, to me, to be an impractical inductor
value.

;-) You just aren't working with small enough, high enough frequency
circuits, Reg.

3 turns of 28AWG on a 4-40 (USA) screw (remove the screw, of course)
will give you about 18 nH. Unloaded Q at 440MHz will be around 200.

The link to the schematic is:
http://www.radiotronix.com/downloads/433_pair.pdf

Easy enough to use SMT components soldered to a piece of copper-clad
for a ground plane. Just put down the two caps and the shunt resistor
"tombstone" style, one end soldered to the ground plane and the other
up in the air, separated by enough distance to put the series coil and
resistor between them. You can keep the parasitic L and C very low
indeed this way. You can also use tiny squares of copper-clad glued
down to the ground plane as tie points.

It's also possible to mechanically make a simple circuit like this on
copper-clad using surface mount parts, by scribing lines with
something like an X-Acto knife and removing strips of copper. In this
case, I could see scribing four lines across the board, separated by
about 1/16 inch, and removing two copper strips, one from between the
first and second scribe, and one from between the thrid and fourth
scribe. That leaves a trace about 1/16 inch wide. Cut gaps in the
trace, about 1/16 inch long, where you want to solder down series
components. Solder shunt components across from the trace to the
copper ground plane. Bridge across the trace with a copper strap to
connect the two gound plane sides, with the bridge up in the air over
the trace. Nice to have a ground plane on the opposite side, with
some holes and wires to connect to the top-side ground planes, but not
necessary. I'm thinking 0805 parts with the sizes I mentioned...make
things slightly larger for 1206. You can make the trace be a 50 ohm
transmission line if you want, by sizing things right.

Cheers,
Tom