MFJ-259 Instruction Manual
HF/VHF SWR Analyzer
2
POWERING THE MFJ-259
The MFJ-259 requires between 8 and 18 volts for proper operation. Any power supply used
with the MFJ-259 must be capable of supplying 200mA of current. An optional power
supply, the MFJ-1312B, is available from MFJ.
The MFJ-259 has a standard 2.1 mm coaxial type jack on the top right edge of the case. This
jack is labeled "12VDC" and has the word "POWER" near it. A pictorial polarity marking
appears on the case near the power jack. The outside conductor of the plug must connect to
the negative supply voltage and the center conductor of the plug must connect to the positive
voltage. The internal battery pack is automatically disconnected when an external power plug
is inserted in this jack.
SWR measurement will be inaccurate when the supply voltage falls below 7 volts. To avoid
false readings, the battery should be checked after storage to ensure the supply voltage does
not drop below acceptable levels.
WARNING:
Never apply unfiltered AC or incorrectly polarized DC to this jack. Peak
voltage must never exceed 18 volts.
BATTERY INSTALLATION
If batteries are used, they must be installed by removing the 8 Phillips head screws on each
side of the case. The eight batteries fit in two separate battery holders with the positive
terminal of the batteries positioned toward the round fixed connection, and the negative
terminals toward the springs of the battery holder.
The battery case has two external terminals that connect to a "pigtail" that has two terminals
on it. This connector looks like the type used for 9 volt transistor radio batteries and connects
in the same way.
Do not attempt to use 9 volt batteries with this unit
. After the batteries are
installed in the plastic holders and the connections are made to the battery packs, the battery
holders can be slid directly into the chrome retaining clips on the cover.
MFJ recommends the use of ALKALINE AA cells to reduce the risk of equipment damage
from battery leakage. Avoid leaving any batteries in this unit during periods of extended
storage.
REMOVE WEAK BATTERIES IMMEDIATELY!
Carefully check the following:
•
The battery packs are positioned so that they do not interfere with any internal parts of
the MFJ-259.
•
The leads are positioned to reach with the cover in the original position.
•
The wires are not pinched between the cover and the chassis.