p. As the transmitter frequency is moved about
m. If it is still impossible to obtain a unity swr,
in normal operating procedures, watch the swr, and
connect the antenna to the terminal marked SHUNT,
if it becomes excessive, begin the tuning procedures
and connect a jumper from the terminal marked
SERIES to ground. Then repeat h, i, and k above at
q. A combination of ANT OUTPUT C and
the same tune adjusting ANTENNA OUTPUT C
SERIES COIL settings may optimize the minimum
along with the controls in h and i above.
reflected power indication.
A number of
n. If a unity swr cannot be obtained with any of
combinations of settings of the above controls may
produce resonance. In general, the highest dial
probably beyond the range of the antenna coupler.
setting for ANT OUTPUT C producing resonance
However, the coupler should handle almost any
will produce the best results.
reasonable antenna with the exception of very short
r. Make a log of the settings for each frequency.
antennas at low frequencies (less than 1/8
If there are no changes in the antenna system, it
wavelength below 7 MHz). Where unity swr cannot
should be possible to return to a given frequency by
be obtained, use the minimum Swr that can be
setting up the dial numbers without having to go
obtained. If the swr cannot be made less than 2.5 to
through the entire tuning procedure.
1, the antenna length should be either increased or
decreased until a better match can be made.
12-5. Operator's Maintenance
o. Note that on the higher frequencies (20 to 30
MHz), the setting of the various controls becomes
quite critical. When tuning adjustments are made,
Operator's maintenance instructions are covered in
adjust the controls slowly so that the proper setting
paragraphs 3-19 through 3-22. Cleaning is covered
will not be passed over too quickly to be noticed.
12-6. Operator's Preventive Maintenance Checks and Services Chart for Coupler,
Item to be inspected
Equipment is not
Check for damage or corrosion.
Connectors cause SWR to be
unable to be corrected.
12-7. Organizational Maintenance Instructions
Organizational preventive maintenance instructions are covered in paragraphs 3-26, 3-26, and 3-27. Touchup painting is
covered in paragraph 3-29.
12-8. Organizational Preventive Maintenance Checks and Services Chart for Coupler,
Item to be inspected
Terminate tuning unit in dummy load. While
changing control settings observe VSWR. SWR
will remain constant. If not, check tuning unit
Change 6 12-3