Pll Section; Receiver Section - Standard Horizon HX751 Service Manual

Alignment

PLL Section

PLL Reference Frequency
 Connect the wattmeter, dummy load, and frequency
counter to the antenna jack.
 Set the transceiver to CH16 (156.800 MHz) then turn
the transceiver off.
 Press and hold in the PTT, [ SQL ] , [  ] , and [  ] keys
while turn the transceiver on to enter the alignment
mode.
 Press the [  ] or [  ] key to select
the display to "rEF xx rEF xx rEF xx rEF xx". rEF xx
 Press the [ CLR/WX ] key to enable
adjustment of the PLL Reference
Frequency.
 Press the PTT key to transmit the transceiver, if nec-
essary, press the [  ] or [  ] key to adjust the frequency
so the counter frequency is 156.800 MHz (±100 Hz).
 Press the [ CLR/WX ] key to save the new setting.
 Press and hold the [ POWER ( )] key for 2 seconds to
turn the transceiver off.
NOTICE!
Do not touch the "AtFSk xx AtFSk xx", "FSk0 xx AtFSk xx AtFSk xx AtFSk xx
xx xx xx xx xx", "FSk2 xx FSk2 xx FSk2 xx FSk2 xx FSk2 xx", and "oFSt xx oFSt xx oFSt xx" parameters. oFSt xx oFSt xx
Wattmeter
Dummy Load
Frequency
Power Supply
10
FSk0 xx FSk0 xx FSk0 xx", "FSk1 FSk0 xx FSk1 FSk1 FSk1 FSk1
RF Signal
Generator
RF Sampling
Inline
Coupler

50
Counter
7.4 V DC
( ) :
RED
Regulated
( ) :
BLACK

Receiver Section

RF Squelch Hysteresis Adjustment
 Press and hold in the PTT, [ SQL ] , [  ] , and [  ] keys
while turn the transceiver on to enter the alignment
mode.
 Press the [  ] or [  ] key to select
HS rF xx HS rF xx
the display to "HS rF xx HS rF xx". HS rF xx
 Press the [ CLR/WX ] key to enable
adjustment of the RF Squelch Hys-
teresis level.
 Press the [  ] or [  ] key to set the display to "HS rF 02
 Press the [ CLR/WX ] key again to save the new set-
ting.
RF Squelch Threshold Adjustment
 Adjust the RF Signal Generator output level –10 dBμV
(with a standard FM modulation: ±3.0 kHz deviation
@ 1 kHz) at 156.800 MHz.
 Press the [  ] or [  ] key to select
the display to "tH rF xx tH rF xx tH rF xx tH rF xx". tH rF xx
 Press the [ CLR/WX ] key to read the
RF Squelch Threshold data.
 Press the [ CLR/WX ] key again to save the new set-
ting.
RF Squelch Tight Adjustment
 Adjust the RF Signal Generator output level 0 dBμV
(with a standard FM modulation: ±3.0 kHz deviation
@ 1 kHz) at 156.800 MHz.
 Press the [  ] or [  ] key to select
ti rF xx ti rF xx
the display to "ti rF xx ti rF xx ti rF xx".
 Press the [ CLR/WX ] key to read the
RF Squelch Tight data.
 Press the [ CLR/WX ] key again to save the new set-
ting.
AF Signal
Generator
MIC
HX751
CLR
WX
HS rF 02". HS rF 02 HS rF 02 HS rF 02
GND