User's Manual
Table Of Contents
- 1. General Description
- 2. Installation and Operation
- 3. Options
- 3.1 T01 Programmable Channel Spacing
- 3.2 T02 Programmable CTCSS encoder/decoder
- 3.3 T03 Programmable DCS/CTCSS encoder/decoder
- 3.4 T05 Balanced and Isolated VF plus E&M
- 3.5 T06 Simplex Changeover Relay
- 3.6 T08 VF Delay
- 3.7 T09 300Hz Upgrade HPF Filter
- 3.8 T10 Power Save Mode
- 3.9 T11 Combined Options
- 3.10 T12 External Reference Oscillator Input
- 3.11 T13 Local Speaker, Mic Socket and Front Panel Mute
- 3.12 T14 Local Channel Change
- 3.13 T16 1PPM Frequency Stability
- 3.14 U69 Extended Temperature Range Verification
- 3.15 T19/26 Line Interface Board.
- 3.16 T29 Balanced and Isolated VF plus E&M
- 3.17 T31 Network Adapter
- 3.18 T34 Ethernet option
- 3.19 T36 Option - TX Ref Oscillator input and Modulator
- 6. MX800 Base Station Fault Finding Procedure
- 7. Appendices
- 7.1 MX800 Interface Connections
- 7.2 CN2 DB9 Female Monitor Connector
- 7.3 CN3 DB25 Female Digital I/O Connector
- 7.4 MX800 Specifications
- 7.5 Channel Select DIP Switch Settings
- 7.6 MX800 Model Number Configuration Guide
- 7.7 MX800 System Applications
- 7.7.1 Conventional base station/repeater
- 7.7.2 Link transceiver
- 7.7.3 Data transceiver
- 7.7.4 Paging transmitter
- 7.7.5 Trunking Base Station
- 7.7.6 Systems base
- 7.7.7 Repeater with Morse ID
- 7.7.8 Simplex base station
- 7.7.9 Duplicated base station
- 7.7.10 Power Save base station
- 7.7.11 Tone key base station
- 7.7.12 Voting base station
- 7.7.13 Simulcast base station
- 8. Superseded Technical Information
- 9. Drawings
MX800 Transceiver Fault Finding
6.4 IF Section
If the Receiver has low sensitivity past this point then increase the RF level to
–60 dBm and check the RX DISC voltage is set to 2.50V. Adjust L14 if
necessary.
Connect a coax lead with a pickup loop around the end from the antenna
input on the HP8920A to the case of X1. Set the HP8920 to TX test, change
the Tune Mode to Manual and change the centre frequency of the comms test
set to 44.545MHz for A to B Band and 89.545MHz for C Band and above.
If CT1 cannot be adjusted to match the above frequencies then X1 may be
faulty.
Set the centre frequency of the HP8920A to the RX freq. + 45MHz for A to B
band or RX freq. + 90MHz for C to M Band or RX freq. – 90MHz for N band
and above.
Adjust the TCXO to within +/- 20Hz.
If the RX centre frequency cannot be adjusted the TCXO may be faulty.
Adjust T1 and T2 for minimum distortion, less than 1%.
If the distortion is high then FL3A, FL3B or FL4 may be faulty.
If the sensitivity is still poor then return the Module to your Service Centre.
6.5 Exciter Module
6.5.1 VCO Locking.
Check the reference frequency of X3 (13 MHz or 14.4 MHz) is the same as
the TX Reference Freq. in the ‘Hardware Settings’ in MXTOOLS’
configuration menu.
Connect a DVM to the ‘TX VCO’ TP on the Microcontroller PCB and check
the TX locking voltage is between 2 – 18 V.
Check that +12V (SKD-2) and 28V (SKD-13) supply lines are present.
If the TX locking voltage is out of spec then slowly adjust CT1 on the TX
VCO a full 360°, and check for a change in the locking voltage.
If there is a change in locking voltage, then realign the VCO voltage to 9V at
centre frequency of the VCO frequency band.
If there is no change in the TX VCO locking voltage then check the VCO
supply voltage at SKU-3 is approx. 7V and with a CRO check the TCXO is
oscillating on pin 8 of IC 10.
If all the above tests pass then the VCO or IC10 may be faulty. Return the
Exciter Module to your nearest Customer Service Centre
.
© SPECTRA ENGINEERING 2008 Revision 4.3.1B
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