The 'Rock-Mite '
A simple CW transceiver

Rockmite.jpg

 

    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:

http://www.hamgadgets.com

 

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.

 

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Dave Benson, K1SWL

March 24, 2010