MFJ-259B Instruction Manual
HF/VHF SWR Analyzer
4
1.3 Frequency
Range
The
FREQUENCY
switch selects the following internal oscillator frequency ranges. (A small overlap outside
each range is provided):
1.8 - 4 MHz
4 - 10 MHz
10 - 27 MHz
27 - 70 MHz
70 - 114 MHz
114- 170 MHz
2.0 POWER
SOURCES
+
Read this section before connecting this device to any power source. Improper connections or incorrect
voltages may cause damage to this product!
2.1
External Power Supply
MFJ has an optional power supply, the MFJ-1315, that satisfies all external supply requirements. We
recommend only using this supply.
Voltage must be more than 11 volts, and preferably less than 16 volts, when the unit is on and operating.
Maximum “sleep mode” and “OFF” voltage (when the power supply is lightly loaded by this unit) is 18 volts.
The supply must be reasonably well filtered. The supply must
not
have a grounded positive lead!
The MFJ-259B can be used with an external low voltage dc supply’s (MFJ-1315 AC adapter recommended).
The ideal supply voltage is 14.5 volts dc, but the unit will function with voltages between 11 and 18 volts. The
current demand is 150 mA maximum. (Be sure you read the battery instructions if you use also install batteries!)
The MFJ-259B has a recessed 2.1 mm power-type receptacle near the RF connectors. This receptacle is labeled
“POWER 12VDC”
.
The outside conductor of the
POWER
receptacle is negative, the center conductor positive.
Inserting a power plug in the “
POWER 12VDC”
receptacle disables internal batteries as a power source.
Internal batteries, although disabled for operating power by inserting a power supply plug, can still be trickle
charged.
WARNING: REVERSE POLARITY OR EXCESSIVE VOLTAGE CAN DAMAGE OR DESTROY
THE MFJ-259B. NEVER APPLY MORE THAN 18 VOLTS, NEVER USE AC
OR POSITIVE GROUND SUPPLIES!
2.2
Using Internal Batteries
When batteries are initially installed, a small black-plastic internal jumper must be re-positioned or checked for
proper position. The battery setting jumper is located inside the unit at the top of the printed circuit board near
the area of the OFF-ON switch and power connector. This jumper is accessed by removing eight screws along the
both sides of the MFJ-259B. After the cover mounting screws are removed, remove the entire back cover. The
black plastic jumper fits over two of three adjacent pins. It must be properly positioned for the type of battery
used (either rechargeable or non-rechargeable).
