One of the new QRP kits that arrived at OzarkCon was the highly anticipated HillTopper 20, the first new design from Dave Benson, K1SWL since closing the door on his Small Wonder Labs.

It’s being kitted by the 4SQRP group with help from David Cripe, NM0S.

It hasn’t yet appeared on the group’s Web page, but I believe the regular price will be $80 when it becomes available again. I picked one up for the special show price of $70.

Here are a few details from the manual:

  • Frequency coverage: 14.000 to 14.350 MHz
  • Tuning: 100 Hz /20 Hz steps
  • TX power output: 5W nominal. Receive current draw: approx..60 mA
  • Size: 4.35” x 3.95” x 1.07”, weight 8 oz
  • ‘On-the-fly’ CW speed control. Iambic mode A, 8-35 wpm
  • Adjustments: BFO trim cap, one-time Frequency Calibration
  • Frequency readout: Audio Morse
  • SMT Parts (2): Pre-installed

The receiver is adapted from K1SWL’s ‘SW+’ Series with minor modifications. The front-end circuitry was revised to replace the now-vanished 10.7 MHz IF transformers. The output of 1st mixer U1 is transformed to a 220 ohm value by L3/C8. The following crystal filter has a -3dB bandwidth of approximately 400 Hz. L4 and C12 step the impedance back up into the 2nd mixer U2. Trimmer capacitor C53 provides adjustment of the BFO frequency during the alignment process. The two op-amp stages following provide approximately 60 dB of audio gain. The final audio stage is configured as a bandpass filter centered on 800 Hz with a Q of 2. The receiver output is suitable for headphone use. An 800 Hz sidetone is injected into this final stage.

The transmitter strip closely resembles Steve Weber’s – KD1JV- fine work. The frequency source for both transmitting and receiving is an Adafruit Si5351 board.

The controller IC is a 28-pin DIP- the Atmel ATmega328P used in the Arduino UNO. It relies on an external 16 MHz crystal for its timing. The application firmware was written in the Arduino environment. An on-board rotary encoder outputting 24 pulses-per-revolution provides a tuning function.

The variable DC voltage provided by Speed pot R16 is read by an A/D converter and scaled for Morse code timing. A pair of inputs are used for dot/dash paddles, and Straight-key mode is also available. The remainder of the I/O provides various control signals and sidetone for a variety of operations.

The Hilltopper firmware was written in Arduino’s (mostly) C language and supported by its own compiler. The firmware is open-source and can be downloaded.

In a letter to the 4SQRP mailing list, K1SWL said “I’ve built 3 of them so far, including a one-of-a-kind for another band. Mine put out 5-6 watts”.

Keep an eye on the 4SQRP Web site for availability.