Note
This device is attributed to ITC, FDK, and KLM.
QST, Jun 1975, p. 112. (ITC)
QST, Oct 1975, p. 123 (KLM)
QST, Jan 1976, p. 117. (KLM)
2000A
QST, Jan 1977, p. 148.
Already on sale in this ad, so the "A" version may have been released earlier than this.