Icom IC-78 Instruction Manual - Page 40

7 INSTALLATION AND CONNECTIONS s CR-338 HIGH STABILITY CRYSTAL UNIT By installing the CR-338, the total frequency stability of the transceiver will be improved. r Remove the supplied internal crystal and replace with the CR-338. q Remove the bottom cover as shown in the previous diagram. w Disconnect W2 from J4401 (MAIN unit) and W3 from J4201 (MAIN unit). e Remove 9 screws from the PLL unit, disconnect P4 from J201 (MAIN unit) and P2 from J401 (MAIN unit), then remove the PLL unit. CR-338 Internal crystal PLL unit PLL unit C 16 W 2 W 3 J 4201 J 4401 P 4 J 201 J 401 MAIN unit P 2; Frequency check point (Connect a frequency counter and adjust the frequency to 64.00000 MHz with C 16.) Solder the 4 leads t Return the PLL unit, plugs and flat cables to their original positions. y Adjust the reference frequency at C16 using a frequency counter if desired. • Connect the frequency counter to P 2 (PLL unit). u Return the bottom cover to its original position. s Optional IF filters Several IF filters are available for the IC-78. You can install 1 filter for 455 KHz IF. Choose the appropriate filter for your operating needs. (pgs, 21, 22) D Installation q Remove the bottom cover as shown on the p. 48. w Remove 7 screws, connection cable p1 from J1, p5 from J701, W4 from J4101 and W5 from J4001 and 2 Tr-clampers as shown in the diagram below. e Install the desired 455 KHz filter as shown in the diagram at right. r Mount the filter with the supplied washers and nuts. Optional IF filter P5 P1 J1 W5 J 701 J4101 MAIN unit Tr-clamper W4 Tr-clamper t Solder the 4 leads. y Return the MAIN unit and bottom cover to their original po- sitions. Solder 4 leads After filter installation, specify the installed filter using initial set mode. (p. 33) Otherwise, the installed filter will not function properly. 38