MFJ-269D Instruction Manual LF/HF/VHF/UHF SWR Analyzer
19
Resonance Mode
functions like other SWR and impedance modes, with the exception the
Impedance
meter measures only reactance. This allows the operator to easily locate frequencies where system
reactance crosses zero.
5.4.1.6
Match Efficiency
Match Efficiency
is the final measurement mode in Advanced-1. To access it, enter
Advance-1
and
press
Mode
three times -- or step to it from any other location in Advanced-1.
The entry screen is shown
below:
Match Efficiency
is yet another way of describing SWR. It is similar to
Mismatch Loss
, but the SWR data
is expressed as a “percentage of forward power” as compared to “reactive” or “circulating power” within
the system.
Important Note:
The term
Match Efficiency
may mislead those unfamiliar with SWR and energy transfer
in a RF system. Power “transmitted” or transferred to a load can be nearly 100% even when a match
efficiency calculation or display indicates a system has
nearly zero percent match efficiency
. Conversely,
match efficiency can measure nearly 100%, and the actual power at the load might be very low due to
system losses.
Match efficiency
only
applies to the
loss in power transfer
from a perfect 50-ohm fixed tuned source to
the input of the feedline or system where the measurement is made. It is mostly useful in laboratory
situations. It does not describe antenna system or feedline efficiency. Even with nearly zero-percent
match efficiency, an antenna system can radiate the applied power with good efficiency. In fact, for any
given amount of "match efficiency", your antenna system could be near 100% or near zero percent
efficient!
Sample Match Efficiency screens are shown below. Note that the bottom screen displays a condition that
is beyond the measurement range of the analyzer.
5.4.2
UHF Advanced-1
To access the Advanced-1 UHF menus, first set up the MFJ-269D for UHF operation:
1.
Rotate
Frequency
to
155-230 / UHF
.
2.
Press in the
UHF
band switch located above the LCD display.
3.
Rotate
Tune
until the screen displays a valid operating frequency and SWR data.
To enter
UHF Advanced-1
, press and hold
Gate
and
Mode
simultaneously for several seconds. As in
LF/HF/VHF operation, you may return to the
Main
(basic) mode by continuing to hold both
Gate
and
Main
buttons -- or by tapping through the Advanced menu sequence (doing so cycles the analyzer
through all available menus).