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The Red Hot 40 is a high performance QRP CW transceiver kit for the 40m band. It has been designed to operate well in the presence of large out-of-band (shortwave broadcast) and in-band (contest station just down the road) unwanted signals. It should easily meet the requirements of most QRP'ers, from the most competitive contester to the casual operator.
The kit contains all the parts needed to build a complete working radio. The only things the user will have to supply are a power source, loudspeaker or headphones, a set of paddles or straight key (suitably wired) and a matched 40m antenna system.
The kit is designed so that no wiring-up is required - all the components are mounted on a single double-sided with plated through holes, solder masked and silk screened printed circuit board that measures 4.5" by 5". Pre-drilled front and rear panels with U shaped top and bottom panels are provided that form a clamshell type case that is smart, strong and functional. The case is red anodized aluminum with an engraved legend.
The Red Hot 40 is a single band QRP CW transceiver optimized for good RF performance rather than for low current drain. As such, it is suited mainly for operation from home-based stations or portable operations with fairly large battery capability (e.g. field day). On receive the current drain can be as much as 150mA. It can produce any output power from 0 to over 5 Watts. The output power is set with a small trimpot inside the rig.
The Red Hot 40 uses fully electronic RX/TX switching (no relays) that gives very smooth, thump-free, semi-break-in operation. The transmit output waveform is edge rate controlled to minimize bandwidth usage. As a bonus, this makes for very nice sounding Morse code on the air. The Red Hot 40 offers many advanced features that make it easy to use.
The Red Hot 40 has a single conversion superheterodyne receiver and an equivalent single stage down-conversion transmitter. The I.F. is 9MHz with the VFO at 2MHz. The Red Hot 40 was originally designed to utilize either a 1 turn or a 10 turn TUNE pot. The Red Hot 40 kit is supplied with a 10 turn pot as standard. The Red Hot 40 also has an RIT pot with center detent.
No frequency calibration or scale is needed because the rig has a built in frequency counter, known as the Audible Frequency Annunciator (AFA). This plays the KHz digits of the frequency to you in Morse code over the speaker/headphones. The AFA has two modes of operation. Manual mode, where the frequency is announced only when you press the front panel pushbutton, and automatic mode, where the AFA "pips" at every KHz as you tune up or down the band, then, recognizes when you stop tuning, and announces the frequency automatically.
The Red Hot 40 has a built in Morse code keyer chip from the Embedded Research TiCK line. This keyer allows you to swap the paddles over, set the speed, tune-up, run straight key mode and run in either iambic A or B modes.
Red Hot 40m Assembly Manual
Red Hot 40 Schematic part 1
Red Hot 40 Schematic part 2
Red Hot 40 Schematic part 3
Red Hot 40 Schematic part 4
Red Hot 40 Schematic part 5