printed circuit board burns.
The code keyer must be connected, even if you don’t
plan to use the Ubitx for Morse Code.
I used an on/off toggle switch for my PTT (push to talk)
switch, but a standard microphone can be added if desired.
There are plenty of schematics online which show how a
hand microphone can be connected to a Ubitx.
The microphone, CW keyer, and speaker are
connected to the Ubitx through three 3. 5 mm sockets
which are included with the kit.
Building My Enclosure
As I’ve done with past projects, I fabricated my
enclosure from a thin metal box which was once used as
a cookie tin. I like using this type of enclosure because
they’re inexpensive and plentiful, and can be found in
many different shapes and sizes.
Perhaps the best feature of using this type of material
is that a nice enclosure can be fabricated by using
common hand tools. Learning how to build an enclosure
from thin gauge metal has at times been tricky business,
but over the years, I’ve acquired a few techniques that
The most difficult task in fabricating an enclosure from
a thin metal box is cutting the opening for the 16x2 mm
LCD. I like to begin by carefully marking the spot for the
LCD opening and then scoring it with a sharp edge. Once
the opening is marked
and scored, I drill four
relief holes; one on the
inside of each corner.
The relief holes will
stop me from cutting
beyond the mark. I use
a rotary tool with a
cutting disc to cut the
the encoder, volume
control, and other parts
are relatively easy to
cut. I prefer to cut these
types of openings with
a hand drill, but some
builders have been
successful using a metal
When laying out
the enclosure, it’s best
to place the openings
for the power and
antenna connector in
the rear panel of the
box. The openings for
the keyer, speaker, PTT, microphone, and volume control
should be placed on the front panel of the box.
Once cutting and drilling are completed, I lightly sand
the box and follow that by applying a coat of automotive
primer. Any primer will likely work, but I’ve found that
paint will adhere to automotive primer quite well. Once
the primer has dried, I paint my enclosure with a lightly
textured paint which is very good at covering scratches on
The Moment of Truth
I’d built a nice enclosure and completed the Ubitx
assembly. The time had now come to test my unit (Figure
10). Like many hobbyists, I’ve often used the term “smoke
test” in a joking manner, but with the Ubitx audio chips
overheating and exploding, that phrase didn’t seem quite
as funny as it once did. It was now time to find out if the
audio chip on my Ubitx was going to work.
I made one more scan of the wiring to ensure each
part was correctly connected and switched on 13. 8 volts of
To my satisfaction and relief, my Ubitx powered up
without blowing the audio chip. As I listened, however,
the audio began to degrade and show signs of distortion.
After operating for a few minutes, the audio became too
distorted to be understood.
I performed the tuning procedure described on Hfsigs.
10. Microbitx transceiver ready for testing.
66 September/October 2018