The Novice Rig Roundup Boosted Pierce Transmitter

Figure 0—The Novice Rig Roundup Boosted Pierce transmitter currently covers only the 40-meter (7-MHz) amateur radio band. The enclosure is a Toy Story lunchbox; the tubes are a 6AB4 triode (Pierce oscillator) and 6JQ6 beam power tube (power amplifier), for both of which a 6JZ8 Compactron can be substituted. Plugging a tube-base-and-crystal-socket adapter into the 5-pin socket allows FT-243 crystals to be used. Power output is 7 watts with 246 V (key down) on the amplifier plate and 150 V regulated on the oscillator plate and amplifier screen. Amplifier-only keying is used to ensure a good-sounding signal; with the 6AB4 and 6JQ6 in use, the backwave (signal leakage through the final amplifier with the key up) is 34 dB down. The toggle switch (KEYING MODE/SPOT) turns on the oscillator for spotting and allows a choice of oscillator-amplifier or amplifier-only keying. (What's the Novice Rig Roundup? Glad you asked!)

Figure 1—Schematic of the Novice Rig Roundup Boosted Pierce transmitter. All wiring of the KEYING MODE/SPOT switch is not shown. Keying waveshaping is done by means of a power MOSFET (IRF840 with 560 pF from drain to gate) in an external keying/control box.

Figure 2—Wiring of the Novice Rig Roundup Boosted Pierce transmitter. Plenty of room is available for the later addition of switching and matching-network components for coverage of 80 and 160 meters.