MFJ-269D Instruction Manual LF/HF/VHF/UHF SWR Analyzer
25
5.
Pressing
Mode
again takes the display to section 5.5.3.2. Pressing
Gate
takes the display to a
Line
Length
adjustment function.
Line length ?
l = 100.0 ft
6.
To
increase
line length, press the
Gate
. To
decrease
line length, press
Mode
. When the desired length
appears, simultaneously press and hold
Gate
and
Mode
to lock it in. The display will now change to:
Line length ?
l = 67.2. ft
7.
Pressing
Mode
switches the display to
Length in Feet
for the degrees programmed in at the selected
Vf
.
5.5.3.2
Line Length in Feet
This mode displays the length in feet required to obtain a certain number of electrical degrees for the
velocity factor (
Vf
) and
Frequency
selected. It is useful for determining the
Physical Length
required
for matching sections, phasing lines, or antennas if the velocity of propagation, electrical length required,
and frequency are known.
This mode is useful for calculating the required length in feet of matching sections and phasing lines if
you know the required variables, velocity factor and electrical degrees. The analyzer can also directly
measure and display length using the distance to fault mode (see section 5.5.1 for HF/VHF).
If this mode is entered after using distance to fault (see section 5.5.1), VF and length will be programmed
automatically using distance to fault data. The physical or electrical length of the line can also be
programmed manually. If a length is not programmed, a default length of 360 degrees is selected
automatically.
1.
Simultaneously press and hold
Gate
and
Mode
buttons until
Advanced-2
appears. The display will
show the default
Vf
(0.66):
2.
Set
Vf
to the desired value (
Gate
to increases,
Mode
to decrease). Then, simultaneously press and
hold
Gate
and
Mode
to lock it in. The
Distance to Fault
screen will appear.
Note:
If you know the true electrical length in degrees, set velocity factor to VF=1.0 and enter the
electrical length in degrees as indicated in step 5.
3.
Press and release the
Mode
button. The display will flash
Line Length in Degrees
.
After a moment, the display changes to (sample screen):