User's Manual Part 2
Table Of Contents
- Maintenance
- Introduction
- Scheduled Maintenance
- Unscheduled Maintenance
- Introduction
- Tools, Materials and Test Equipment Required
- T6T VHF Amplifier Procedures
- Top and Bottom Covers
- Removing and Refitting the Interface Module
- Removing and Refitting the PSU Regulation Module
- Removing and Refitting the Power Supply Modules
- Removing and Refitting the Combiner BIT Module
- Removing and Refitting the PA Modules
- Removing and Refitting the Front Panel PCB
- Removing and Refitting the Cooling Fans
- T6T VHF Drive Assembly Procedures
- Removing the Top Cover
- Removing and Refitting the Processor Module
- Removing and Refitting the PSU Regulation Module
- Removing and Refitting the Drive Module
- Removing the Bottom Cover
- Removing and Refitting the PA Control Module
- Removing and Refitting the Power Supply
- Removing and Refitting the Front Panel PCB
- Virtual Front Panel (VFP)
T6T 300 Watt VHF Transmitter Page 90 Installation
Fig 26 Remote Keying
Fig 27 Phantom Keying
T6T Transmitter
MARC Audio Connector
Audio is pins 1 and 2.
Audio line 1
Audio line 2
PTT
Reference Voltage
(0 V, +14 V or -14 V)
Set from front panel
PTT
Switch
V
PTT
The transmitter reference voltage (0 V, +14 V or -14 V) is selected from the Polarities screen:
❑ PTT is active when V
PTT
differs from the transmitter reference voltage by more than 10 V.
❑ PTT is inactive when V
PTT
differs from the transmitter reference voltage by less than 1 V.
❑ Maximum value of V
PTT
is ±60 V with respect to transmitter reference voltage.
Example:
To use 0 V as the keying potential, V
PTT
= 0 V; set transmitter reference voltage to +14 V; set PTT In to STD.
Cross-Site Lines
Audio
Circuit
PTT input requires at least 1 mA to operate.
Input will draw no more than 6 mA.
PTT is pin 6
MARC Connector
Audio is pins 2 and 3.
PTT is pin 4
MARC or
MARC Audio
Connector
Control
Equipment
Ground is pin 7.
Ground is pin 1.
T6T Transmitter
PTT
Switch
Reference Voltage
(0 V, +14 V or -14 V)
Set from front panel
V
PTT
To reduce the number of cross-site lines between the control site and the transmitter, phantom keying may be employed.
This method has the keying potential (V
PTT
) superimposed on the audio lines instead of using a separate line.
The transmitter reference voltage (0 V, +14 V or -14 V) is selected from the Polarities screen:
❑ PTT is active when V
PTT
differs from the transmitter reference voltage by more than 10 V.
❑ PTT is inactive when V
PTT
differs from the transmitter reference voltage by less than 1 V.
❑ Maximum value of V
PTT
is ±60 V with respect to transmitter reference voltage.
Example:
To use 0 V as the keying potential, V
PTT
= 0 V; set transmitter reference voltage to +14 V; set PTT In to STD.
Audio lines with phantom keying
signal superimposed
PTT input requires at least 1 mA to operate.
Input will draw no more than 6 mA.
MARC Audio Connector
Audio is pins 1 and 2.
MARC Connector
Audio is pins 2 and 3.
MARC or
MARC Audio
Connector
Audio
Circuit
Control
Equipment