MFJ-266 HF/VHF/UHF Antenna Analyzer
Instruction Manual
©
2011 MFJ Enterprises, Inc.
2
2.0 Power Sources
The MFJ-266 may be powered with internal AA batteries
or with an external DC supply. To
avoid needless damage and ensure top performance, please follow the guidelines below when
choosing a voltage source:
2.1 Internal Batteries
Battery power requires
eight (8) AA-size 1.5-volt alkaline cells
. Rechargeable 1.2-volt cells
should not be used because the combined voltage will be too low to meet the unit's 10.8-volt
minimum threshold. Batteries are installed in two fully encased 4-cell plastic trays mounted
inside the analyzer enclosure. To access these, remove all four screws securing the analyzer's
back cover and carefully open the case. Slide the battery box covers sideways to unlatch, then lift
vertically to expose the cells.
Slide and
Lift
Never change batteries with an external power supply connected or when the power switch is
turned on.
Doing so could damage the unit. Note that
alkaline cells are not rechargeable
and the
analyzer has no built-in charging circuitry. When replacing old batteries, be sure to follow the
manufacturer's environmental guidelines for safe disposal. For longest battery life, always
replace with a matched set of factory-fresh cells.
2.2 External Power Supply
Powering the MFJ-266 externally requires a well-filtered DC supply capable of delivering
10.8
to
12.5 VDC
under varying load conditions. Current drain ranges from 30 mA to 180 mA,
depending on operating mode, frequency range, and whether or not the display backlight is on.
Many low-cost 12-volt "wall-wart" adapters are very poorly regulated and may deliver damaging
voltages under variable load conditions. If in doubt, check your supply with a voltmeter before
connecting to confirm it delivers no more than
13 volts or less with no load connected
. The unit's
external power jack is located on the front panel and accepts a standard 2.1-mm power plug.
Positive voltage (+) must be applied to the connector's center pin.
