MFJ-259 Instruction Manual
HF/VHF SWR Analyzer
11
3.0 : 1
3.0 dB
2.5 : 1
3.6 dB
2.0 : 1
4.7 dB
1.7 : 1
5.8 dB
1.5 : 1
6.9 dB
1.2 : 1
10.3 dB
You can estimate the approximate loss at the operating frequency by remembering that the
feedline loss in dB is reduced by 70 % at half the frequency, and increased by 140 % at twice
the frequency you measured. This method is reasonably accurate if the loss is distributed
along the feedline and not confined to one bad area.
For example, assume an operating frequency of 28 MHz. You want to know what the feedline
loss is at 28 MHz. At that frequency the "SWR" meters needle is in the red uncalibrated
portion of the meter. Increase the measured frequency until the needle falls on a calibration
mark. At 60MHZ the meter reads 3:1 SWR. Using the chart you know that the loss is 3 dB.
Since 28MHz is about half of 60MHz, you can multiply 3dB by .7 which gives a loss of about
2dB at 28MHz.
ADJUSTING TUNERS
The MFJ-259 can be used to adjust tuners. Connect the MFJ-259 "ANTENNA" connector to
the tuner's 50 ohm input and the desired antenna to the normal tuner output. This connection
can be made with a manual RF switch to facilitate rapid changeover.
WARNING
: Always connect the common (rotary contact) of the switch to the tuner.The
switch must connect either the MFJ-259 or the station equipment to the tuner.
The Station Equipment Must Never Be Connected To The MFJ-259.
1.
Connect the MFJ-259 to the tuner input.
2.
Turn on the MFJ-259 and adjust it to the desired frequency.
3.
Adjust the tuner until the SWR becomes unity (1:1).
4.
Turn off the MFJ-259 and re-connect the transmitter.