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Small Wonder labs SW+ Monoband Transceiver

The 'SW+' series is Small Wonder Labs' current offering in the CW monoband kit market. This CW transceiver board kit is an updated version of the classic '40-40' transceiver first fielded by the New England QRP club. This design was subsequently published in the November '94 issue of QST and serves as a centerpiece in the ARRL's recent anthology, 'QRP Power".

Here's the overview of this family's design features:

  • Single-board transceiver, 2.8 x 4.0" (7 x 10.1 cm)
  • Commercial-quality board, masked and silkscreened
  • True VFO: 35-40 khz coverage
  • Superheterodyne design, with crystal filtering
  • Quiet solid-state T-R switching (QSK)
  • Output Power Adjustable- 2.5W max.

The SW+ series retains much of the original receiver design, while augmenting the transmitter design for improved stability and output power. The following design changes went into making a classic even better:

  • Added power supply reverse-polarity diode
  • The number of toroids to wind drops from 8 (in the orginal) to 5. This pays off in faster and simpler assembly.
  • The diode bridge T-R switch is replaced by a series L-C type. This drops receiver current draw from 22 to 16 mA and improves image rejection.
  • The crystal filter is changed from 2 to 3 crystals for improved skirt selectivity. A grounding point for the crystal cases is also provided to reduce filter 'blow-by'. For the 30M version, the IF has been changed. This relocates the image response to virtually eliminate SWBC pickup.
  • Replaced a number of local oscillator components for improved reliability and stability.
  • The PA is a T0-220 device, capable of more output power than the original. Should you wish to modify the design slightly for more power, there's now space for a TO-220 heatsink.
  • The interconnects have been functionally-grouped. The board kit-only builder may wire directly to the board in convenient wiring groups. The companion enclosure kit provides locking .100" headers, with pre-assembled harnesses. The new board is 'drop-in compatible' with prior versions of the SW-series enclosure kit.
  • The printed-circuit board is now double-sided and solder-masked both sides. Component silkscreening is improved, and all parts are identified on the silkscreen by both outlines and reference designators.

Enclosure Kit:

An enclosure kit is available for the SW+ series. This resembles the earlier SW-series enclosure with a number of improvements.

The kit includes a customized Ten-Tec TG-24 enclosure, which measures 4.1"(W) x 4.0"(D) x 2.0"(H). It's a handsome two-tone (black/grey) finish, and is now silkscreened on both front and rear panels.

As add ons QRPproject offers the Freq-Mite keyer/counter and the RIT-KIT for the SW+ Series 

German or English manual

Orders can be placed in our WEB shop:


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