Sea Air and Land Communications 1178 Manual De Usuario
11-78-0000 SYNTHESIZED NRZ DATA TRANSMITTER PRODUCT INFO
Issue 11787TA
11-78-0000 SYNTHESIZED NRZ DATA TRANSMITTER PRODUCT INFO
Issue 11787TA
Sea Air and Land Communications Ltd
Page 4
Sea Air and Land Communications Ltd
Page 5
9.0
TUNING AND TEST
Equipment required.
!
PC running PROCOMM or BGTERM.
!
11-46 programmer between 1178 and PC comm port.
!
Power supply. 13.8v 2A.
Frequency and Loop Voltage adjustment.
!
Connect the transmitter to a test set with coax.
!
Check +5v and +12v and check green light is blinking.
!
Send “SALTREE” then “TD”, then “C”, (TX on, low speed mod)
check voltage on “loop” test pad.
check voltage on “loop” test pad.
!
Tune L2 for a nominal loop voltage of 2.5v If above 2.5v, adjust L2
core inwards, if below 2.5v, adjust L2 core outwards.
core inwards, if below 2.5v, adjust L2 core outwards.
!
Check red light is on.
!
Test voltages on the test point +8v.
!
Send command “A”, (data = 1) then hold down “1" until the read
back number is 040. (This sets modulator to mid point).
back number is 040. (This sets modulator to mid point).
!
Adjust CV1 for transmitter centre frequency error of 0.0kHz
±200Hz.
±200Hz.
Carrier deviation adjustment.
!
With conditions as per end of previous section above:
!
Send command “1" or “2" until transmitter frequency is +4.5kHz
±100Hz. (High DAC value), or +2.25kHz (for 12.5kHz channeling)
±100Hz. (High DAC value), or +2.25kHz (for 12.5kHz channeling)
!
Send command “B” (data = 0)
!
Send command “3" or “4" until transmitter frequency is -4.5kHz
±100Hz. (Low DAC value) or -2.25kHz.
±100Hz. (Low DAC value) or -2.25kHz.
!
Send command “C” (slow modulation)
!
View modulation on test set scope and adjust RV2 until edges and
corners of waveform are clean, with minimum overshoot.
corners of waveform are clean, with minimum overshoot.
Output Power tuning and adjustment.
!
Conditions as per end of previous section:
!
Adjust Q13 quiescent current with no RF present. With a metal
screwdriver crowbar L7 to the side of the frame and rotate RV3 for
an increase in total supply current of 100-150mA. Check this when
hot. The quiescent current should be 150mA maximum
screwdriver crowbar L7 to the side of the frame and rotate RV3 for
an increase in total supply current of 100-150mA. Check this when
hot. The quiescent current should be 150mA maximum
!
Send command “8" or “7" until value of 001 to 010 is obtained
1178 Topside Components