ZETRON 025-9581M, Installation And Maintenance Manual

Page: 185 / 196

185
Setting Levels in the Model 620x
Setting FFSK Levels in a Wire Line-based system
The following procedures are very similar to the ones used in radio-based system;
however, in some cases the specific pots used have changed. It also matters whether the
wire-line system is 2-wire or 4-wire. Pay close attention to ensure that you adjust the
correct controls.
♦
Setting the Model 6203 receive level:
1. At the Model 6203 location, connect an oscilloscope to measure the receive audio
signal at TP-1 on the Model 6203 motherboard. The expected signal will be
approximately 1.0 Vp-p (0.35 Vrms).
2. On the Model 6203 motherboard, set controls R107 and R135 according to
whether this is a 2-wire or 4-wire system.
• 2-wire = turn R107 fully counterclockwise and R135 fully clockwise
• 4-wire = turn R107 fully clockwise and R135 fully counterclockwise
3. Turn R62 (FFSK IN) fully counterclockwise. Set R86 ( VOX threshold) to the
middle of its range.
4. Call the Model 26 site and have the operator there initiate the FFSK Test signal
from the Model 26.
a. At the Model 26, connect the laptop (or PC) to the serial programming port of
the Model 26. Hit the SPACE bar three times to open the Model 26 Main
menu.
b. Enter a “ 7 ” to open the {7} FFSK Test Menu.
c. Enter a “ 1 ” to initiate the FFSK test mode. The Model 26 should key its radio
and transmit for 30 seconds and then unkey. If you finish making adjustments
before 30 seconds is up, you can cancel the test by hitting any character key on
the computer keyboard. If you require more time to make the adjustments,
enter the “
1 ” again to repeat the test tone.
5. If the voltage measured at TP-1, while the test signal is being received, is less than
1.0 Vp-p (0.35 Vrms), turn R62 clockwise until it reaches 1.0 Vp-p .
6. If the voltage measured at TP-1, while the test signal is being received, is greater
than 1.0 Vp-p (0.35 Vrms):
• 2-wire = turn R135 counterclockwise until it is reduced to 1.0 Vp-p (0.35
Vrms)
• 4-wire = turn R107 counterclockwise until it is reduced to 1.0 Vp-p (0.35
Vrms).
7. When finished making adjustments, let the test signal time-out or stop the test. If
this is the last transponder you are setting the receive level on, you may exit the test