The 'Rock-Mite '
A simple CW transceiver
The
'Rock-Mite' design grew out of my desire to offer a 'one-evening' CW
transceiver kit which would be both affordable and easy to construct. It first
appeared at 'Lobstercon' - a QRP gathering on the Maine coast- in early July,
2002, where it was provided to all attendees courtesy of Small Wonder Labs and
the NorCal QRP club. It appeared in QST magazine in 2003, and since then, it’s
been wildly successful. Approximately 8000 of these have been fielded so far!
The Rock-Mite is a crystal-controlled direct-conversion transceiver available
for 80M, 40M, 30M or 20M. It
features an on-board 8-pin PIC microcontroller which controls a T-R offset on
key-down. A brief tap of a pushbutton control switch reverses the offset to
yield a second operating frequency. Pushing and holding on the pushbutton
activates the speed adjustment routine for the built-in Iambic keyer. If you'd
rather use an external keyer or straight key, there's a 'drop-through' mode
which allows use of an external keying source.
You'll note
in the image above that the Rock-Mite uses two crystals. The first is used in
the local oscillator for transmitter and receiver. The second is used as a
receiver front-end filter. This crystal significantly reduces the SWBC energy
present at the receiver mixer; as a result, unwanted SWBC reception is
dramatically reduced.
The
Rock-mite uses one surface-mount part with fairly large spacing. There are no
toroids to wind, so assembly should be a snap! The Rock-Mite uses subminiature
epoxy-encapsulated RF chokes instead of toroids.
SPECIFICATIONS:
- Double-sided PCB 2.0" x 2.5", plated-thru-holes,
solder masked & silkscreened for easy assembly
- 0.5W power output at 12V supply.
- Supply voltage range 8-15V
AVAILABLE
FREQUENCIES:
3560 kHz
3579 kHz
7015 kHz
7030 kHz (QRP calling frequency)
7040 kHz
7122 kHz
10106 kHz
14060 kHz
-automatic T/R offset, reversible
-Built-in Iambic keyer, 5-40 WPM
-Built in sidetone, 700 Hz
- Includes assembly instructions and operating tips
- All on-board parts supplied in kit (as pictured above)
|
Check out
this offering! Dale
Botkin, N0XAS, offers an economical upgrade to the RockMite functionality. The'PicoKeyer'
provides memory-keyer functions, and with one added resistor, allows
pot-based speed control. For
further information, see: |
ENCLOSURE OPTIONS:
We do not offer an enclosure for the
Rock-Mite. It's 'Altoids-compatible', however, so a source of enclosures
is probably as close as your nearest market or pharmacy! For a beautiful
custom-made enclosure, check out the 'MityBox' available from http://www.americanmorse.com/
CONNECTORS
& CONTROLS
We now offer a complete set of
controls/connectors for the RockMite. Includes:
BNC bulkhead, (2) 3.5mm stereo jacks, gain
pot, knob, power jack & plug (2.1/5.5mm), power and interconnect wire,
subminiature switch, reverse polarity diode, instructions. This parts set is
'Mitybox'-compatible. If you’d prefer to gather these parts yourself, Mouser
Electronics’ part numbers are listed under the RockMite section of this
website’s ‘documents’ page.
Dave Benson, K1SWL
March 24, 2010