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Paper, Scissors, RockMite – the Small Wonder Labs QRP Kit Radio 26 - October - 2007

Posted by k9zw in K9ZW Built, K9ZW Recommends.
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The RockMite Exposed

The ‘Rock-Mite’ was designed by Dave Benson K1SWL, and as he puts the reasons so well, from his website:

The ‘Rock-Mite’ 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.

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
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

AVAILABLE FREQUENCIES:

3560 kHz, 3579 kHz, 7030 kHz (DX QRP calling frequency), 7040 kHz (N. America QRP calling frequency), 7122 kHz (US Novice/Tech+), 10106 kHz or 14060 kHz

ROCKMITE LINKS:

Small Wonder Labs

WY3A’s “The RockMite Rocks” pages

N0RC’s “The RockMite Files” pages

Yahoo Groups RockMite Group

eHam RockMite Reviews

Google Search on RockMite

Mity Box enclosure by American Morse

BUILD EXPERIENCE:

This kit is a blast to build. Though I took more than one evening to build mine, mostly due not being organized for the build. I put mine in a Mity Box by American Morse and the results are awesome! This is one fun build!

I am afraid I lost my in-process build pictures when the Macbook’s aftermarket large hard drive stopped driving, but the RockMite is well documented on the web.

Highly recommended!

73

Steve
K9ZW

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Comments»

1. B. Scott Andersen - 27 - February - 2008

There are lots of pictures in the step-by-step assembly manual I just published in the Yahoo! RockMite Files area. Enjoy!

— Scott (NE1RD)


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