Note
This is a just a restyling of the famous HD-19 phone patch and was done to bring the unit into line cosmetically with the SB series. Electronically the HD-19 and the HD-15 are virtually the same device. Other than the cabinet change to Heath’s “low boy” style, the most obvious change is that the station mic does not connect to the phone patch, as in the HD-19. Instead, the mic is connected to the transceiver in the normal way, and the patch connects to jacks provided on the back of the SB series transmitters and transceivers. The HD-15 is a simple device and works very well. There is very little to go wrong. It is easy to install, adjust, and use. The HD-15 was a very successful product and was on the market for 17 years. It was replaced by the HD-1515—becoming part of Heath’s “little brown box” series. Two-tone green wrinkle.
Telephone line input impedance: about 600Ω
Null depth: at least 30 db isolation between transmit and receive circuits
Receiver impedance: effective match from 3 to 16Ω
Transmitter impedance: 600Ω or high impedance
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
