click to enlarge
(click image to enlarge)


by William Eric McFadden

From the manual:

The Heathkit Model HW-8 Transceiver is a solid-state, four-band QRP (low power) unit covering the CW portion of the eighty, forty, twenty, and fifteen meter amateur bands. The direct-conversion receiver features an RF stage, a balanced product detector, and an active audio filter wide or narrow selectivity.
Other features include diode band switching which is controlled by pushbuttons and a method of premixing the variable and heterodyne oscillator signals to provide the same dial read-out on all bands. This also provides excellent stability and a fixed frequency offset on all bands while you are transmitting.
In addition to indicating Relative Power, the panel meter is used during alignment to assure proper adjustment of the transmitter tuned circuits.
The HW-8 Transceiver may be operated from the Heathkit Accessory Power Supply Model HWA-7-1, an equivalent low impedence power supply, or from batteries.
Specifications:

General



Frequency Coverage 80 meters, 3.5 to 3.75 MHz



40 meters, 7.0 to 7.25 MHz



20 meters, 14.0 to 14.25 MHz



15 meters, 21.0 to 21.25 MHz


Frequency Stability less than 150Hz/hour drift after 60 minute warm-up


Frequency Generation premixed VFO and HFO


Power Requirements 13.4 volts DC, nominal. 90mA receive mode and 430 mA transmit mode


Dimensions 9-¼" wide x 8-½" deep x 4-¼" high, including knobs and feet



(23.5cm wide x 21.6 cm deep x 10.8cm high)


Weight 4 lbs. (1.8kg)

Transmitter



DC Power Input 80 meters -- 3.5 watts



40 meters -- 3.0 watts



20 meters -- 3.0 watts



15 meters -- 2.5 watts


Frequency Control built-in VFO


Output Impedence 50 ohms unbalanced


Sidetone built-in, adustable volume


Spurious and
Harmonic Levels
at least 35dB down


Transmit Frequency Offset approximately 750 Hz lower, fixed on all bands

Receiver



Receiver Type direct conversion with RF amplifier, balanced product detector, and active audio filter


Sensitivity 1 microvolt or less for 10dB (S+N)/N 0.2 microvolt provides readable signal


Selectivity Wide -- 750 Hz at 6dB down



Narrow -- 375 Hz at 6dB down


Passband Center Frequency 750 Hz


Type of Reception CW


Audio Output Impedance 1000 ohms nominal

scan of HW-8 Manual Cover from Technology Systems

The HW-8 was the second QRP transceiver offered by Heathkit. It replaced the HW-7 and was offered between 1976 and 1983. While it looked similar to and was the same size as the HW-7, the HW-8 featured a much more sophisticated direct-conversion receiver design and included 80 meters. In all respects, the HW-8 is a rig far superior to the HW-7. The original price of the HW-8 was $139.95.

I have owned two HW-8 transceivers. An unmodified HW-8 was the first rig I purchased following the 1989 fire. This was my only HF rig for some time and many contacts were made with it. I implemented several simple mods within this HW-8, including a fix for transmitter offset and the installation of an internal 100kHz crystal calibrator.

I sold this rig to help pay for the QRP Plus but soon regretted having let it go. After I purchased an HW-7, seeing it on the shelf only served to make my longing for another HW-8 stronger and I finally purchased another HW-8, the one I currently own.

The HW-8 is designed for use with high-impedence mono headphones. Before I found a proper set of vintage Trimm Featherweight headphones, I used modern low-impedence stereo headphones with an impedence adapter (image) built around a Radio Shack #273-1380 audio transformer.

from 1978 Heathkit catalog -- click to enlarge

I have installed a Small Wonder Labs Freq-Mite (link) in my HW-8; this clever frequency counter announces the VFO frequency in morse code in the headphones at the press of a rear-panel button, allowing me to know my precise frequency no matter where on the dial I am. Because several hams have asked about this installation, I've written up instructions.

An extremely useful reference on the HW-8 is Michael Bryce's HW-8 Handbook, Second Edition. This book provides circuit descriptions, schematics, board layouts, alignment instructions, Heathkit service bulletins, and modifications for the HW-7, HW-8, and HW-9. It is available at Michael Bryce's The Heathkit Shop, at Kanga, USA, and at QRP ARCI. The older, First Edition, HW-8 Handbook has modifications for the HW-7, HW-8, and HW-9 but lacks the other valuable content.

The articles written by Adrian Weiss, W0RSP, for CQ Magazine (May, 1977; August, 1977; October 1977; January 1981; and October 1982) are also valuable resources worth looking for.

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HW-8 Links


Attributions:

HW-8 Instruction Manual cover found at Technology Systems.
Heathkit 1978 catalog page found at Technology Systems.