MFJ-836H SWR/Wattmeter and RF Ammeter
Instruction Manual
3
needles cross. The SWR is indicated by the red curve closest to the needle
crossing point.
8.
The RF Ammeter measures RF current in three calibrated ranges: 3 Amperes, 10
Amperes, and 30 Amperes. Simply turn the Current Range knob to the desired
range.
9.
The
meter is scaled from 0 to 100. On the 10A range, move the decimal point 1
place to the left (100 = 10 A). To convert meter readings made on the 3A and
30A ranges, multiply accordingly. For example, a reading of 85 on the 30A range
equals 30 x .85, or 25.5 A. See Table 1 below to estimate readings quickly.
10.
To prevent meter pegging, begin checks on a high range and work down. To
estimate unknown current levels, use the formula below (I = Unknown Current in
Amps, P = Applied Power in Watts, and R = Load Resistance in Ohms).
I
P
R
=
Range
3A
10A
30A
Meter
Reading
Actual Value (Amps)
10
0.3
1.0
3
20
0.6
2.0
6
30
0.9
3.0
9
40
1.2
4.0
12
50
1.5
5.0
15
60
1.8
6.0
18
70
2.1
7.0
21
80
2.4
8.0
24
90
2.7
9.0
27
100
3.0
10.0
30
Table 1: Actual Current Value
RF Hazard--Important Warnings:
1.
RF-current measurements must be conducted with extreme caution. Physical contact with
conductors carrying even moderate RF-energy levels can result in severe RF burns, or injury.
2. Avoid measuring RF currents on conductors where high RF voltages may be present (>500
Volts). Damage to your meter may result.
Using the MFJ-836H continuously for more than 1 minute
on the 30 A range may present these high RF voltages. When operating on the 30 A range, we
recommend operating at 10% duty cycle to prevent damage