Eico HM-90
The Eico HM-90 is a line-type RF wattmeter for ham and hobbyist use. It sits in the transmission line between a transmitter and its antenna. It reads power output in two ranges, 0-10 watts and 0-100 watts, and it also indicates standing wave ratio on a 52-ohm line. The circuit is vacuum-tube based, a VTVM type that senses the RF levels. It is calibrated at the factory, with a calibration control and range switch on the panel. It runs on 110-120 volts AC at 60 cycles and draws only 10 watts.
The instruction manual states that frequency coverage extends to 220 MHz, with response flat to ±0.5 dB. It plugs into the wall and has no power switch. It was sold as a self-contained, portable instrument. The HM-90 appears in the Eico catalog line of the mid-1960s. A period mention in High Fidelity (1964, p.122) lists it among precision hi-fi accessories, though without detail.
Surviving information on this model is thin. No production years, original price, dimensions or weight are documented, and no formal reviews have surfaced. What is known comes from the operating manual and a single eBay listing. The seller called it a "vintage Eico HM-90" RF wattmeter, noted it "lights up and meter responds to signals," and mentioned minor cosmetic wear - light rust on the back panel and scuffs consistent with age. The listing pitched it as "good for ham radio" use, which is the audience it was built for.
Known specs:
- Frequency coverage: extends to 220 MHz
- Frequency response: flat to ±0.5 dB
- Power ranges: 0-10 W and 0-100 W
- Input impedance: 52 ohms (calibrated line)
- SWR measurement: reads standing wave ratio on 52-ohm lines
- Power: 110-120 VAC, 60 cycles, 10 W consumption
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