Note
The HM-2103 is a wattmeter and a dry dummy load in one package. It was (and still is) a very useful product. Designed for HF use, its operating range is from 1.8 to 30 MHz. It will provide a 50Ω non-reactive load with 1.2:1 SWR over the full range.
The load resistor (Heath part number 1-3-10) will handle 175 watts continuously, 500 watts for 5 minutes, and 1000 watts for 2.5 minutes. Heath suggested that a fan could be installed to help cool the resistive element. A HI TEMP indicator light warns of high temperature conditions. This circuit is activated by a thermal switch and requires a 9 volt battery. Caution: do not use the load without the perforated RF shielding in place. Without the shield the load will radiate RF energy.
A front panel switch selects two power ranges (0-200 watts and 0-2000 watts) and a high-temp indicator lamp/battery test. The HM-2103 cabinet is light green and the front panel is wrinkle green. These are still highly sought-after units.
References:
Brief description. Popular Electronics, Jun 1973, p. 108.
Review. QST. Sep 1973, p. 46.
Frequency range: 1.8 to 30 MHz
Wattmeter range: 0 to 200 and 0 to 1000 watts
Wattmeter accuracy: ±10% of full range
Power rating: 175 watts continuous, 1000 watts maximum; see derating curve
Overload indication: red light activated by thermal switch (requires 9 volt battery, NEDA 1604)
SWR: less than 1.2:1
Load type: non-inductive, solid carbon element
Load impedance: 50Ω nominal
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.