sided PCB pads) or hot-glued to the
ground plane.
Figure 5 shows a typical “ugly
construction” example. This is a
Hartley oscillator for the amateur 40-
meter band around 7 MHz. In fact, I
used a telegraph key to turn this
oscillator on and off, making a
couple of “QSOs” or contacts with
nearby hams using the few milliwatts
of power (also known as QRP power)
from this mighty peanut whistle!
If you are envisioning doing
some RF building yourself, an RF
prototyping board is a useful
workbench addition. You’ll need a
large piece of single- or double-sided
PCB (at least 8” x 8”) and a thick
piece of wood as big as or slightly
larger than the circuit board.
Drill mounting holes in the
corner of the PCB and attach it to
the wooden base with wood screws.
This gives you a large surface on
which to work, plus the base makes it
heavy enough to not be dragged
about by test leads and cables. I
attached rubber feet to the bottom of
my wooden base.
Once you’ve finished (and before
each use), scrub the board with a
Scotch-Brite™pad to remove
fingerprints and oxidation. A swab
with some rubbing alcohol will also
clean the board of oils or greases.
The goal is to have an easy-to-solder
surface.
Once you gain a little experience
with this type of construction for RF
circuits, you’ll find it’s a quick and
effective way to prototype even
complex RF circuits before
transferring them to an actual PCB or
building them into an equipment
enclosure. NV
March 2015 63
FIGURE 5. A typical RF prototype
using “ugly” construction in which
ground connections are made directly
to the copper PCB ground plane. This
is a Hartley oscillator for the amateur
40-meter band around 7 MHz.
©2015 Measurement Computing Corporation, 10 Commerce Way, Norton, MA 02766 • info@mccdaq.com
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