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Date Posted by Category User IP

2013-11-23 (UTC)


HF Radios

Small Wonder Labs SW20+ Excellent Condition $120

$120 shipped

The SW+ series of single band CW transceivers are designed by Dave Benson K1SWL who sells these little kits under the Small Wonder Labs product name. Originally designed for the New England QRP club as the NE40-40, Dave has updated the circuit and sells SW+ series kits for 80, 40, 30 and 20 meters. They are available as a board kit where the builder provides the case, controls and connectors.

SW+ series transceivers use a single conversion superhet receiver based on the NE602 mixer chip. There is no IF amplifier stage however a second NE602 is used as a product detector. The 20 meter version uses a 9.0 MHz intermediate frequency and has a three pole fixed bandwidth crystal filter. The NE5532 audio amplifier chip is configured as an audio filter centered around 800 Hz to add additional selectivity. The audio output is designed for headphone operation.

The VFO uses varactor tuning and the builder sets the desired tuning range using fixed capacitors provided with the kit. The SW20+ in the photograph tunes from 14.009 to 14.045 MHz. A standard single turn potentiometer is used as the tuning control.

The SW20+ transmitter puts out about 2 watts of power but it can be reduced by adjusting the internal drive control. QSK and keying is very nice. The sidetone uses the transmitted signal as heard by the receiver but there is no provision for sidetone level adjustment.

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