The Heath company from Benton Harbor, Michigan produced a series of three QRP transceiver kits, starting in the 1970's. The first was the HW-7 which sported a direct conversion receiver and a 2 watt transmitter. Band coverage was the CW portion of 40, 20 and 15 meters. It suffered from poor receiver sensitivity and probably was not an effective rig. The HW-7 was manufactured between 1972 and 1975.
The second QRP transceiver kit was the HW-8, produced from 1976 to 1983. It had an improved direct conversion receiver and covered 80, 40 , 20 and 15 meters .
The final QRP kit was the HW-9, offered between 1984 and 1991. It had a very good superhet receiver and with the optional WARC band kit, covered all bands from 80 to 10 meters.
I built the HW-8 in the photograph above in 1977. The direct conversion receiver was pretty good on the three lower bands and not so hot on 15 meters. I got 1.5 watts of output power on the lower bands and less than 1 watt on 15 meters. The direct conversion receiver does suffer from common mode hum when operated from an AC power supply. There is an adjustable time delay on the T/R switching circuit (a relay), not quite QSK, but the rig does has have pretty good CW keying characteristics.
Back in 1977, Heath sold these rigs by mail order for $129. Anyone else remember drooling over the latest Heathkit catalogs? Heathkit was famous for the quality of their instruction manuals. Even today, Heath manuals are the standard by which all other kit manuals are measured.
The HW-8 orginally used a RCA jack as the antenna connector, however many builders changed them to a SO-239 coaxial connector. High impedance headphones must be used with this transceiver. There is a built-in audio filter with a front panel wide / narrow selectivity switch.
Lots of HW-8's were sold by Heath and they appear often at hamfests. They are still very usable on the air once
you learn the peculiarities of the DC receiver.
Updated June 15, 2016