Appendix A- 7
with the additional tuning for secure TX deviation and secure RX
discriminator level tuning.
Transmit Deviation Balance
(Compensation)
When tuning with a secure board installed, the coupling capacitor
inside the RKN4035A Test Cable will cause rolloff of the low port
modulation. To fix this, the cable should be dc coupled (“VOL”
position) and an external coupling capacitor (1.3µF or larger) must be
placed in series with the signal source input to the AC/DC MTR.
Follow the
“Transmit Deviation Balance (Compensation)”
procedure outlined in Section 5, except change step 3 as follows:
3. Set the RTX4005B Test Box meter selector switch to the “VOL”
position, and connect the signal source to the AC/DC MTR port
thru a 1.3µF capacitor. Inject an 80 Hz tone at 100mVrms thru this
capacitor. Keep the ac voltmeter in parallel to the AC/DC MTR
input to ensure the proper input signal level.
Secure TX Deviation
Transmit deviation balance (compensation) and transmit deviation
limit adjustments should be completed before secure deviation is
adjusted. Remember to use the new transmit deviation balance
procedure outlined in the previous paragraphs before performing the
following steps.
1. From the SERVICE menu, press F2 to select TRANSMITTER
alignment.
2. Press F8 to select the SECURE TX DEV softpot.
3. Press F6 to key the radio on the test frequency. The screen will
indicate that the radio is transmitting.
4. Measure the secure deviation on your service monitor.
5. Use the up/down arrow keys to adjust the secure deviation per
Appendix Table 3.
6. Press F6 to dekey the radio. Press F8 to program the softpot value.
7. Press F10 to return to the TRANSMITTER menu.
Secure RX Discriminator
Level
8. Set the RTX4005B Test Box meter selector switch to the “MX
DISC” position, and connect an ac volt-meter (capable of 1mV
resolution on a 2V scale) to the test box AC/DC meter port.
9. From the SERVICE menu, press F3 to select RECEIVER alignment.
10.Press F8 to select the SECURE DISCRIMINATOR LEVEL softpot.
The screen will indicate the receive test frequency to be used.
11.Set the RF test generator to the receive test frequency. Set the RF
Appendix A Table 3. Secure Deviation
Channel Spacing (kHz)
Secure Deviation (kHz)
25 / 30
2.91 - 3.06
20 (VHF / UHF)
1.69 - 1.84
20 (821 - 824, 866 - 969)
1.69 - 1.84
12.5
N / A
Summary of Contents for SYMBOL MT2000 Series
Page 1: ...HT 1000 JT 1000 MT 2000 MTS 2000 and MTX Series Handie Talkie Portable Radios Service Manual ...
Page 2: ......
Page 24: ...2 Notes ...
Page 78: ...56 Notes ...
Page 147: ...Appendix A 9 Appendix Figure 2 Secure Module Location Detail ...
Page 169: ......
