Note
QST, Jul 1962, p. 125.
Allied Radio catalog 1963 (copyright 1962), p. 291.
These units, which Sonar called "Monoband" transceivers, predate Heath's "Single-Bander" transceivers by about a year, and are similar units made by Swan, were introduced concurrently with Sonar's.
Sonar Radio Company released a line of mono-band SSB transceivers in 1962. The transceivers ran 180 watts PEP input on sideband and 160 watts on CW. They used 2.1 kHz Collins mechanical filters and offered sideband selection, as well as VOX or PTT operation. Thise Model 20 mono-bander is shown with the optional "piggy-back" AC supply.
The model numbers are the bands:
Sonar 75
Sonar 40
Sonar 20
Sonar 15
Sonar 10