Note
The MFJ-962D is a "T" network roller inductor tuner with built-in antenna switching, RF power and SWR metering and a 1:1 balun. The largest amplifiers that can safely be used include the Heathkit SB-200 and 201, Collins 30L1, and Ameritron's AL-600 and AL-811 series of amplifiers. This tuner is designed for maximum RF output power levels of 800 watts carrier or PEP on 80-10 meters, and 500 watts carrier or PEP on 160 meters. It is designed to match 50 ohm output amplifiers, transmitters or transceivers to virtually any antenna.
Peak and average forward power, reflected power, and SWR are displayed on the wattmeter's illuminated cross-needle meter.
The MFJ-962D uses a roller inductor "T" matching network. It continuously tunes all frequencies from 1.8 through 30 MHz. It will match dipoles, inverted vee's, verticals, mobile whips, beams, random wires, and many other antennas. The built-in balun will work with balanced open wire, twinlead, or twin-axial feedlines.
An internal six position antenna-selector switch selects two separate coaxial line outputs either in tuned (with tuner's matching network in line) or direct (no matching circuit) configurations, a balanced line output, and a coax bypass position for accessories such as an external dummy load. Long wire antennas can be connected to the center connector of the coax connector.
Understanding Power Ratings
There are no standardized power rating systems for tuners. The names used (i.e. 3 kW Tuner) carry over from the time when amplifiers were rated by peak power input, and not the true RF power output.
For example, the one thousand watt Johnson Matchbox was rated to handle a 1000 watt plate modulated AM transmitter (four kilowatts PEP transmitter input and 3000 watts PEP RF output). The Heathkit SB-220 was called a two kilowatt amplifier, and the rated CW output was approximately 600 watts.
Matching tuners were called 2 kilowatt tuners, and these tuners safely handled 600 watts of CW power and 1200 watts PEP SSB.
The FCC changed the power rating system of amplifiers, and tuners no longer follow amplifier power ratings. Most typical 1500 watt tuners remain able to safely handle 400-600 watts CW, and 600-900 watts PEP SSB.
Load conditions and control settings also greatly affect the power handling capability of the tuner. T-networks typically handle more power on higher frequency bands into higher load impedances. The worst operating condition for T-network tuners are low impedance capacitive reactance loads. T-network
tuners always handle the least power when operated on 160 meters into low impedance capacitive reactive loads.
