Note
73, Dec 1981, p. 91.
The MFJ-812(B) is a low-loss VHF SWR/Wattmeter specifically designed for mobile or base station use The original model could be used only in the 2-meter band. The "B" version added coverage up to and 220 MHz, and changed the color of the cabinet and front panel. The 812 series serves as a diagnostic tool for monitoring transmitter power, measuring Standing Wave Ratio (SWR), and testing relative field strength. Utilizes 1N34 diodes and a 500k potentiometer for sensitivity adjustment.
Features
– Dual-Band Monitoring: Optimized for 144 MHz and 220 MHz operation.
– Triple Functionality: Measures Forward Power, SWR, and Field Strength.
– Built-in Field Strength Meter: Includes a dedicated circuit and rear binding post for a pickup antenna to monitor RF radiated signals.
– Flexible Power Ranges: Supports both 30-watt and 300-watt scales for power measurement.
Specifications
– Frequency Range: 144–220 MHz (primary); functional down to 21 MHz with reduced sensitivity.
– Power Scales: 30 Watts and 300 Watts.
– Impedance: 50 Ohm Stripline design.
… Meter Movement: 100 μA meter.
