Wilderness Radio Sierra
The Sierra is one of the all-time classic QRP radios. Originally developed by Wayne Burdick, N6KR for the NorCal QRP Club, it is currently a commercial product of Wilderness Radio. It was designed in 1994 as a club project and became an instant hit among QRP operators nationwide.
It features a very sensitive superhet receiver with a variable bandwidth crystal filter. The 4.915 MHz crystal filter is adjustable using a front panel ABX control and works really well in crowded band conditions to reduce QRM. The transmitter produces about 3 watts of output power on 80 meters and progressively lower power on the higher bands. Typical power on 15 meters is around 1 to 1.5 watts.
The Sierra is a multiband CW transceiver. Band switching is accomplished by snapping off the cover and swapping band modules. The modules plug into a large edge connector on the main board and band changes can be made in just a few seconds.
The photo shows two band modules. The lower module (15 meters) is shown with the protective cover removed, revealing the 8 toroid inductors and the crystal. Band modules are available from Wilderness Radio for all nine bands between 160 and 10 meters.
Kit builders can customize their Sierra by ordering only the band modules for the bands they are interested in. Additionally, the open construction makes modifications easy to perform.
The VFO is in the 3 MHz region and allows transceive operation over the first 150 kHz of each band. The receive mixer and product detector uses NE602 Gilbert cell mixer chips plus there is one stage of IF amplification using a MC1350 IC.
This rig is a favorite of backpack and portable operators because of it's light weight and very low current consumption. Receive current drain is around 30 mA. Transmit drain is 200 to 450 mA, depending on power output settings. A small gell cell battery will last for many days of casual operation.
Under the hood of the Sierra, the band module occupies the center of the main board. The VFO tuning capacitor is in the lower right corner while the transmitter PA transistor (with heat sink) is visible in the upper left. The KC2 digital readout accessory module is mounted on the front panel.
The basic Sierra is available as a kit from Wilderness Radio with an analog frequency readout dial. The optional KC2 module adds digital frequency readout, power meter, S Meter and iambic CW memory keyer functions to the rig. Additionally, the optional BuzzNot noise blanker can be added to reduce impulse noise problems.
Recent editions of the ARRL Handbook has featured the Sierra transceiver as a construction project for several years.