Motorola Astro Digitalport Saber Basic 68p81076c05 Manual

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SECTION VII.  BASIC THEORY OF OPERATION
A. Introduction to This Section
The following theory will help isolate the problem
to a particular board. Using circuit board replacement
as the basic service approach will maximize working-
time of the radio.
B. General Overview
The ASTRO Digital SABER radio is a wideband,
synthesized, fixed-tuned radio available in the 
VHF, UHF, and 800MHz bands. All ASTRO Digital
SABER radios are capable of both analog operation 
and ASTRO mode (digital) in 12.5kHz or 25kHz...

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active mixer coupled by transformers. Injection is pro-
vided by the VCO through an injection filter. See Table
14 for local oscillator (LO) and first IF information.
The frequency generation function is performed by
three ICs and associated circuitry. The reference oscil-
lator provides a frequency standard to the
synthesizer/prescaler IC, which controls the VCO IC.
The VCO IC actually generates the first LO and trans-
mit-injection signals and buffers them to the required
power level. The...

A. Introduction to This Section
This section of the manual contains troubleshoot-
ing charts, error codes, a functional block diagram,
interconnect diagrams, and flexible circuit information.
This section will help you isolate a problem to the
board level. Board-level troubleshooting does not
attempt to isolate problems to the component level.
Component-level service information can be found in
the ÒASTRO Digital SABER Portable Radios Detailed
Service Manual.Ó (Refer to ÒRelated Publications Avail-
able...

D. Operational Error Codes
During radio operation, the radio performs dynam-
ic tests to determine if the radio is working properly.
Problems detected during these tests are presented
as error codes on the radioÕs display. The presence ofan error code should prompt a user that a problem
exists and that a service technician should be contact-
ed. Use Table 16 to aid in understanding  particular
operational error codes.
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Table 16.  Operational Error Code Displays
Error Code Description Corrective Action...

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Symptom Possible Cause Correction or Test (Measurements Taken at Room Temperature)
No RF Power 1.  TX Power Level Check TX power level and frequency programming (from RSS).
Out or Frequency
2.  No PTT From With the PTT switch depressed (radio transmitting/keyed), check for INT PTT 
Control Top at P901 pin 6 of the control top/PTT flex; 
if not there, replace the control top/PTT flex.
3.  No Injection To Check LOCK DETECT at pin 13 of the RF board connector; 
Power Amplifier if not between 1.0 and...

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NOTES