The tuning procedure should be performed after initial installation or startup of a system or when
an operational check is required. All the steps in the procedure should be performed in the
sequence they are listed.
b. Transmitter Tuning Procedure. The procedure used for tuning the transmitter is listed
in steps. Along with each procedural step is a normal indication which tells you what should
happen when the step is performed. Use the Fold-Outs in the rear of the booklet to aid you in
visualizing what happens during the tuning operation. A brief outline of the transmitter tuning
procedures can be found on your job aid card.
STEP 1.
With all AC POWER switches off, check to see that the equipment is
connected correctly for the assigned type of operation. The types of
connections were covered earlier under cable connections.
STEP 2.
Check that the antenna is in the assigned azimuth position. This operation
was covered in a previous lesson. Review if necessary.
STEP 3.
Refer to Fold-Out 11 while reading this step. Set the transmitter XMTR
CHANNEL indicator (Item 11) to the assigned channel number by turning the
XMTR CHANNEL control (Item 10) until the desired channel number
appears in the indicator window.
Set the transmitter XMTR TUNE indicator (Item 13) to the same channel
number by turning the XMTR TUNE control (Item 12) until the channel
number appears in the indicator window.
It may be necessary at some time for you to convert an AN/GRC-103 channel
number into a frequency. The formula to accomplish this is as follows.
If you know the frequency in MHz and want to convert it to an AN/GRC-103
channel number, you would use this formula.
Channel Number = 2 X Frequency in MHz - 400
STEP 4.
Close Fold-Out 11 and open Fold-Out 12. Refer to Fold-Out 12 while reading
this step.
On the Receiver RF Head set the XMTR CHANNEL indicator (Item 15) to
the same channel number as used for the Transmitter RF Head. Do this by
turning the XMTR DUPL control (Item 14) until the channel number appears
in the indicator window.
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