Note
260
QST, Feb 1969, p. 103.
270
QST, Oct 1969, p. 149.
270B
QST, Jul 1970, p. 4.
QST, Feb 1971, p. 105. (Specification)
QST, Oct 1972, p. 144.
QST, Jan 1973, p. 109.
The 260 and 270 were sold side by side through 1970. After 1970 the 260 appears to have been discontinued. (QST, Feb 1971, p.107.)