TM 11-6625-2718-14&P
FUNCTIONING OF EQUIPMENT
2609A/U enables maintenance personnel to ef-
fectively troubleshoot a radio set by providing
a. When rf power is transmitted through a
readings that depict the amount of forward and
transmission line to a load, this power or energy is
reflected rf power in a transmission line.
termed as a forward traveling wave. If the load on
b. The TS-2609A/U contains a short trans-
this transmission line is of the correct ohmic value
mission line (uniform airtype line section) that
(matched), all the power that traveled to the load
acts as a very accurate 50-ohm load from which
is consumed by the load. If the ohmic value of the
correct measurements of the forward and reflected
load is of some other value (mismatched) than the
power are taken. This line section contains two
correct value, the load does not consume all the
separate sensing units (fig. 5-l). One unit senses
initial power. This unused power reflects and
the amount of forward power, and the other unit
travels back along the transmission line, and is
senses the amount of reflected power.
t e r m e d a reflected traveling wave. The TS-
used to determine the ratio between forward and
reflected powers. This ratio of forward power
a. In the traveling wave concept, the forward
divided by reflected power provides the voltage
and reflected waves traveling on a transmission
standing wave ratio (swr) which is an indication
line produce voltage and current maximum and
of the efficiency of the load or antenna (matched
minimum points along the transmission line
load or mismatched load). Graphs have been
(standing waves). These standing waves do not
provided (fig. 2-3 and 2-4) to eliminate the need
affect the readings of the TS-2609A/U since the
for computation to obtain the swr. A low swr
TS-2609A/U reads only forward and reflected
indicates an efficient load or antenna, whereas a
traveling waves.
high swr reveals either a defective antenna or an
b. After the forward and reflected power levels
open transmission line.
have been read in watts and recorded, they can be
