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by William Eric McFadden

From the manual:

The Model HW-7 Heathkit Transceiver is a three-band QRP (low power) CW Transceiver with both built-in VFO and crystal transmit provisions. Band coverage is the CW portion of forty, twenty, and fifteen meters. The Transceiver can be operated from the Heathkit Accessory Power Supply Model HWA-7-1, an equivalent low impedence power supply, or batteries. The experienced amateur, QRP man, and novice alike will appreciate the dependability and versatility of this Transceiver.
Whether you use it for standby, camping, emergency operation, or your primary rig, the Transceiver will prove its worth. Band changing and tune-up are easily accomplished with pushbutton band selection and single-control Tuning. The light-weight and compact Transceiver has pushbutton crystal transmit provisions for the novice or QRP roundtables. Main tuning is accomplished through a 6-to-1 vernier that is virtually backlash free. A Relative Powermeter, built-in sidetone, and carry-along size make the Transceiver a pleasure to operate.
Specifications:

 General



Frequency Coverage 40 meters, 7.0 to 7.2 MHz



20 meters, 14.0 to 14.2 MHz



15 meters, 21.0 to 21.3 MHz


Frequency Stability less than 100 Hz drift after 10 minutes warmup


Power Requirements 13 volts DC, nominal. 35 mA receive mode and 450 mA transmit mode


Active Devices synchrodyne detector, 40673 dual-gate MOSFET



audio amplifier, CA3035V1 integrated circuit



VFO and buffer, MPF105 JFET



doubler/tripler, MPS6521 silicon transistor



driver, MPS6521 silicon transistor



final amplifier, two MPSU05 silicon transistors



sidetone oscillator, 2N3393 silicon transistor and X29A829 silicon transistor



break-in keying, 2N3393 silicon transistor and X29A829 silicon transistor



transmitter keying, S2091 silicon transistor


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


Weight 4 lbs. 8 oz.

Transmitter



DC Power Input 40 meters -- 3 watts



20 meters -- 2.5 watts



15 meters -- 2 watts


Frequency Control 40 meter crystal or built-in VFO on 40 meters



20 meter crystal or built-in VFO on 20 meters



15 meter crystal or built-in VFO on 15 meters


Output Impedence 50 ohms unbalanced


Sidetone built-in


Spurious and
Harmonic Levels		 at least 25dB down

Receiver



Sensitivity less than 1 microvolt provides readable signal


Selectivity 2 kHz at 6dB down


Type of Reception CW or SSB


Audio Output Impedance 1000 ohms nominal

The HW-7 was the first QRP transceiver offered by Heathkit. It was available from 1972 through 1975. The HW-7 provided coverage of 40, 20, 15 meter bands. The transceiver featured a very simple direct-conversion receiver design and this simple design led to performance problems including sometimes-severe broadcast-band interference, microphonics, and AC hum. According to the January, ARRL review (January, 1973), the original price of the HW-7 was about $70.

scan of HW-7 manual from the Boat Anchor Manual Archive I built an HW-7 in the late seventies when I held a Novice license. The kit was purchased on close-out from Heathkit after the introduction of the HW-8. (If memory serves, the close-out price was $40, and my parents paid half.) This rig was a miserable performer and very few contacts were made with it. I had installed a choke to reduce common-mode hum and an MFJ CWF-2 four-stage active audio filter. This HW-7 was lost in the 1989 fire.

My current HW-7 was purchased from NS8O who had significantly improved the receiver's front-end. This rig is a much better performer than my original one was and is pleasant to operate.

The HW-7 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.

I plan to install a Small Wonder Labs Freg-Mite audible frequency counter (link) in my HW-7 at some point. This clever device announces the VFO frequency in morse code at the press of a button and will allow me to know my precise frequency no matter where on the dial I am.

An extremely useful reference on the HW-7 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.

HW-7 Links

Attribution: scan of HW-7 manual cover from the Boat Anchor Manual Archive.