JRC JLR-7700MKII Instruction Manual page 72

(3) Correction to the Loran C time difference
The Loran C time difference to be displayed can be corrected.
Press the key provided on the right hand side of the TD CORR, then, enter the correction value.
Example) In case it is necessary to correct the TD1 by +0.5
Press the 0 , 5 , and ENT keys.
Then, press the +/- , 1 , 1 , and ENT keys.
JLR-7700 MK 2 GPS Navigator
s and TD2 by -1.1 s.
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