Note
QST, Jul 1962, p. 125.
These units, which Sonar called "Mono-Band" transceivers, predate Heath's "Single-Bander" transceivers by about a year. Similar units made by Swan were introduced concurrently with Sonar's.
The model numbers are the bands:
Sonar 75
Sonar 40
Sonar 20
Sonar 15
Sonar 10