Note
The HW-10 and its twin, the HW-20 “Pawnee," were designed and sold mostly as mobile rigs but have a built-in three-way vibrator power supply allowing them to be run from 120 VAC, 6 VDC, or 12 VDC. Maybe that’s what makes them so heavy.
The HW-10 is built around 15 tubes and covers from 49.8 to 54.0 MHz using separately tunable VFOs for transmit and receive (it is not a true transceiver). It will run both AM and CW and features illuminated slide-rule dials and a rather clever exciter stage design that tracks along with the VFO, thus permitting single-knob tuning. Interestingly, the HW-10 and 20 also include a public address function.
Other features include temperature stabilization of the VFO, selection of four crystal frequencies, CAP and MARS operation, a spotting switch, a tunable BFO, and a built-in low pass filter with a 54 MHz cut off.
Transmitter power output is about 8 watts CW and 10 watts AM from a 6360 final amp.
The front panel contains an illuminated S/relative power meter and controls for AM/CW, AVC on/off, AF and RF gain, BFO on/off/pitch, ANL on/off, squelch, final tune, spot on/off, receiver and transmitter tune, VFO/ crystal selector and a public address mode.
There are rear panel controls for modulation level (pull out for public address operation), and a modulation monitor on/off switch. Rear panel connections include jacks for key and headphones, a grounding post, a RCA jack for a public address speaker, a 15-pin Jones plug for power input, and an SO-239 RF connector. Crystals are accessible through a rear panel cover plate. The internal speaker is mounted on the right side of the cabinet, as view from the front.
The public address function will provide up to 15 watts of power to drive and external 8Ω speaker. Depressing the PTT button on the microphone allows PA operation. The receiver may also be monitored using the PA function.
Placing the rear panel modulation monitor switch in the on position and plugging in a set of headphones allows monitoring of the modulation on the RF carrier. This switch is normally in the off position. When off, receiver audio is routed to the headphones.
When Heath designed this rig, it pulled no punches. The bottom cover plate, for example, is held on with no fewer than 36 screws. Heath packed a lot of point-to-point wiring and parts into a small space, and the tuning mechanisms are a frightening collection of gears, pulleys, and cords. Bringing one of these back to life will challenge even the most experienced of restorers.
Supplied with a Turner 350C ceramic microphone, also sold separately as the GH-12. Refer to GH-12 for specifications.
The HW-10 is painted in the two-tone green color scheme. Early units had satin finish metal knobs, while later ones used polished metal TX-1 style knobs.
CRYSTAL FREQUENCY CALCULATION
operating frequency = crystal frequency x 6
References:
Brief description. Electronics World, Mar 1961, p. 120.
Increasing spotting signal. QST. Sep 1962, p. 62.
Alignment problems. CQ. Oct 1962, p. 98.
Squelch trouble (brief). CQ. Mar 1965, p. 67.
RF output indicator. CQ. Feb 1966, p. 76.
Receiver
Frequency coverage: 49.8 to 54.0 MHz
IF frequencies:
first IF: 22 to 26 MHz (tunable)
second: 2.0 MHz
Noise figure: 6 db or less
Sensitivity: 0.5 µV will provide a signal better than 10 db above the noise
Squelch threshold: less than 1 µV
Selectivity: 15 kHz at 6 db down
Image rejection: better than 70 db
IF rejection: 50 db
Input impedance: 50 to 72Ω, unbalanced
Audio output power:
receiver: 3 watts
public address: 15 watts
Headphone jack: low impedance
External speaker: 8Ω
Transmitter
Frequency coverage: 49.8 to 54.0 MHz (crystal or VFO)
Modulation: 0.01 volt minimum at 1000 Hz = 100%
RF output power (into 50Ω load):
AM: 8 watts nominal
CW: 10 watts nominal
Distortion: 10% or less with 100% modulation at 1000 Hz
Mic: high impedance ceramic
Output impedance: 50 to 72Ω, unbalanced
Low pass filter: 54 MHz cutoff
Crystals frequency range: 8.333 to 9.0 MHz
Crystal type: FT-243
General
Power requirements:
6 VDC at 14.5 amps transmit and 8.5 amps receive
12 VDC at 7.5 amps transmit and 4.5 amps receive
120 VAC at 1 amp transmit and 0.5 amps receive, 120 watts transmit, 60 watts receive
Tubes: (1) 0B2, (1) 6AK6, (1) 6AN8, (1) 6BH6, (1) 6BS8, (2) 6EA8, (1) 6DZ7, (3) 6BJ6, (2) 6AQ6, (1) 12AX7, (1) 6360
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
