52 October 2017
watt with a 12 volt supply.
This was an easy kit to build and the manual was
straightforward. The kit worked right away. I certainly
recommend this one if you can find one. Other models are
available for the 80, 40, and 20 meter bands.
One of the most unusual units I discovered is the QRP
Pixie. This is a 40 meter transceiver that uses two transistors
and one IC (refer again to Figure 2). I got my unit from
NightFire Electronics for around $10 ( www.vakits.com).
It’s a bit primitive, but unique in design. The schematic is
shown in Figure 3. It starts with a crystal oscillator driving a
final transistor stage and a Pi network that connects to the
antenna. It puts out about 100 m W with a nine volt battery
supply. You can get more with a 12 volt supply.
This circuit also works as a receiver. When not
transmitting, the S8050 final transistor power amplifier
serves as a mixer. It mixes the input signal from the
antenna with the always-on crystal oscillator signal down
to an audio signal that is amplified by a 386 audio power
amp IC. As crazy as it sounds, it does work, although the
bandwidth is too wide and there is little selectivity. Tuning
is done by a pot you have to adjust with a screwdriver.
Cheap but not ideal.
Just so you know, there is no manual or instructions
with the kit, just a schematic. You have to match the
component numbers on the schematic to those on the
PCB. Some of the parts were not marked. I ended up
measuring most of the capacitors with my DMM. I got the
inductor color code from an Internet search. Connecting
the speaker, antenna, key, and power are a nuisance with
the screw-type connectors. Nevertheless, I like this little kit
because of its uniqueness.
If you want a cheap and dirty transmitter, try the one
shown in Figure 4. It uses a single 2N3904, 2N2222, or
equivalent transistor, and a nine volt battery or 12 volt
supply. I used a 7.040 MHz crystal.
The only hard part to find is probably the 365 pF
variable capacitor. I had one in my junk box left over from
a crystal radio project. The
antenna was just a long wire,
but it works. I’m not sure how
much power output is, but my
guess is only a few milliwatts —
One thing I would like
to try is a vacuum tube kit. I
used a one tube 11 watter as
a novice on 80 meters and
worked all states. I also had a
6V6 10 watter later during my
poor college days. It worked
great too. I did not realize that
I was a QRPer at the time. It
would be fun to try that again.
There are lots of QRP kits
out there. Just do an Internet
search on QRP kits and spend
some time digging through
the pile. There are plenty of
for you at low cost. Check
out the many kit reviews at
products/22 to see what
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Figure 2. Two kit transmitters: the Ramsey QRP- 30 on the
left and QRP Pixie on the right.
Figure 3. Schematic of the QRP Pixie from NightFire Electronics that is both a
transmitter and receiver. (Courtesy Night Fire Electronics; www.viakits.com).