Note
QST, Sep 1951, p. 115. (referred to as the "S-9")
QST, Oct 1951, p. 106.
QST, Jun 1953, p. 85.
QST, Oct 1956, p. 98. (NOS??)
Along with the 2 meter model pictured, the Sonar SR-9 was also made in 6 and 10 meter versions for either AM or FM. The 9-tube receiver was compact enough for mobile use and had 3 watts of audio. An external power supply was required.