Note
HDP-121 1976-1977 $39.95
HDP-121A 1978-1980 $44.95
Introduced a couple of years before the SB-104.These mics can be assembled so that the PTT switch is on the stem (as in left photo), or the base (right). The PTT switch on the HDP-121 is black. A less expensive red switch is used 121A. Both models are “non-reflecting” gray.
Element: dynamic
Frequency response: 70 to 10000 Hz
Impedance: Hi-Z
Output level: –57db
Case: die-cast zinc and cycolac (plastic)
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.