Larcon FMT-24 Technical Manual

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FMT- 25 VHF FM TRANSLATOR

862-09725

FMT-25

VHF FM TRANSLATOR

TECHNICAL MANUAL

Issue 1A:

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Page 1 FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL Issue 1A:...
Page 2: Table Of Contents
FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL CONTENTS: Introduction General Description Technical Specifications Operating Information Installation Information Technical Information Maintenance information Issue 1A:...
Page 3: Introduction
FMT- 25 VHF FM TRANSLATOR 862-09725 INTRODUCTION This Manual contains the Operating, technical and installation information for the F M T- 25 VHF FM Translator. The FMT-25 forms part of a new range of Professional VHF FM Re-broadcasting equipment produced by Broadcast Solutions Electronics. Issue 1A:...
Page 4: General Description
FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL General Description Issue 1A:...
Page 5 FMT- 25 VHF FM TRANSLATOR 862-09725 GENERAL DESCRIPTION The F M T- 25 VHF FM Translator is a compact unit requiring only 1U Rack space. The unit is designed for use in VHF FM Stereo Broadcasting in the 87.5MHz to 108MHz, band.
Page 6 FMT- 25 VHF FM TRANSLATOR 862-09725 d) PSU Module (980808). Each module is Field replaceable, in line with BSE’s maintenance philosophy. This allows the customer to change a module, or to upgrade options easily. 4. FUNCTIONAL DESCRIPTION. Refer to the Front and Rear panel layout in figure 1. 1) RF monitor (BNC 50 ohms female).
Page 7 FMT- 25 VHF FM TRANSLATOR 862-09725 Figure 1: Front and Rear panel layout. Issue 1A:...
Page 8 FMT- 25 VHF FM TRANSLATOR 862-09725 Figure 2: Schematic Diagram of FMT-25 Issue 1A:...
Page 9: Technical Specifications
FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL Technical Specifications Issue 1A:...
Page 10 FMT- 25 VHF FM TRANSLATOR 862-09725 FMT- 25 SPECIFICATIONS Electrical characteristics Typical Rx Sensitivity: 75kHz-deviation reference with 75uS de-emphasis (Stereo) RF Input level Stereo S/N ratio 20uV 50dB 50uV 56dB 100uV 60dB 500uV 70dB 1000uV 75dB Rx Static selectivity: RF Filter, IF Filter and Rx baseband filter Frequency offset Selectivity ±...
Page 11 FMT- 25 VHF FM TRANSLATOR 862-09725 Rx baseband performance: Stereo with 75kHz deviation and de-emphasis off. Tested at 1mV, RF input. Frequency Distortion Separation Crosstalk ≤ 0.25% ≥ 50dB ≥ 50dB 30Hz ≤ 0.25% ≥ 50dB ≥ 50dB 1kHz ≤ 0.25% ≥...
Page 12 FMT- 25 VHF FM TRANSLATOR 862-09725 Environmental Specifications 115V ± 10% (230V Optional) A/C Input power A/C Frequency variation 50Hz to 60Hz DC Input power +24V Battery (+24V to +28V) Power consumption Approximately 70W Storage temperature -40°C to +60°C Operating temperature -10°C to +45°C Relative Humidity 20% to 90% non condensing...
Page 13 FMT- 25 VHF FM TRANSLATOR 862-09725 Telemetry controls and alarms (via 15-pin D type female connector). Pin number on SK17 Description Pin 1 Ground Pin 2 Rx Mute (Contact s/c to ground when muted) Pins 3 and 4 RF PA Temperature Fault (Voltage free contact, s/c when fault) Pins 5 and 6 RF PA VSWR Fault...
Page 14: Operating Information
FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL Operating Information Issue 1A:...
Page 15 FMT- 25 VHF FM TRANSLATOR 862-09725 OPERATING INFORMATION Translator Applications: • Stand alone Translator: When used with VHF receive and Transmit antennas. • High power Translator: When used with VHF receive and Transmit antennas and Wideband VHF RF Amplifier. • Translator with Space Diversity: When used with VHF receive and Transmit antennas with a Reserve Receiver connected in Diversity mode.
Page 16 FMT- 25 VHF FM TRANSLATOR 862-09725 Indicating LED’s: • A/C Supply: Green led indicates A/C power is On. • EXT DC: Green led indicates +24V ext. DC power is On. • Rx PLL Lock: Green led indicates PLL lock is achieved. •...
Page 17: Installation Information
FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL Installatio n Information Issue 1A:...
Page 18 FMT- 25 VHF FM TRANSLATOR 862-09725 INSTALLATION INSTALLATION STAND ALONE CONFIGURATION (FM Translator) The following information sets out the general requirements for installation and operation of the above equipment in a "stand alone" configuration. Note: The operating frequency will normally be set at factory configuration, but if a different operating ( receive or transit) frequency is necessary then the unit top cover has to be removed and a new frequency selected on the Translator main PCB .
Page 19 FMT- 25 VHF FM TRANSLATOR 862-09725 TX PLL LOCK (green led) RF FAULT (red led) VSWR FAULT (red led) TEMP FAULT (red led) TL ID (yellow Led) AC SUPPLY (green led) EXT DC (green led) RX PLL LOCK (green led) MUTE (red led) PROGRAM LOSS (red led) PSU FAULT (red led)
Page 20 FMT- 25 VHF FM TRANSLATOR 862-09725 The external cables and connectors are not normally supplied as standard kit, and due to the various customer configurations the cable and connector requirements must be requested by the customer . Issue 1A:...
Page 21: Technical Information
FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL Technical Information Issue 1A:...
Page 22 FMT- 25 VHF FM TRANSLATOR 862-09725 TECHNICAL INFORMATION CIRCUIT DESCRIPTIONS MAIN PCB ASSEMBLY (378-Z0027) ♦ Receiver Circuits operation. Synthesizer and Local Oscillator (76.8MHz-97.3MHz) The synthesizer consists of a single modulus loop with a divide by 64 pre-scaler (IC6). A 12.8MHz TCXO (IC7) provides an accurate and stable reference for the synthesizer. The reference is then, divided by two by IC30/A to 6.4MHz.
Page 23 FMT- 25 VHF FM TRANSLATOR 862-09725 10.7MHz IF Filter section. The 10.7MHz IF output from the Mixer MX1, is routed via Links LK1 and LK2 which are usefully configured to allow testing of the Rx Front-end or IF Filter. With LK1 ‘in’ and LK2 ‘out’ the Front-end IF output can be monitored at SK3. With LK1 ‘out’...
Page 24 FMT- 25 VHF FM TRANSLATOR 862-09725 100kHz (IC13/B). The total filter is flat (± 0.25dB) to 95kHz and gives ≥20dB attenuation at 150kHz. No adjustment of the filter is necessary. The baseband output from buffer IC15 pin 6 is routed via R112 to SK5 (Rx baseband output) this output, whose level is adjustable via R111, is used for external use.
Page 25 FMT- 25 VHF FM TRANSLATOR 862-09725 R182 provides the adjustment for the Tx baseband input, and R183 provides the Auxiliary input (SCA or SST). The RF output at SK10 and the RF Buffer amplifier (IC23) is switched via TR12 to ensure the output is switched off when the synthesizer is out of lock.
Page 26 FMT- 25 VHF FM TRANSLATOR 862-09725 from the Display module. The output of this IC is routed via R243 to SK14 (PA ALC) and is used to control the RF output on the RF Power amplifier module. The output of the Temperature alarm circuit IC27/B is also routed to the ALC circuit via R237 such that when the Temperature alarm is activated it reduces the RF output power.
Page 27 FMT- 25 VHF FM TRANSLATOR 862-09725 RF Enabled is indicated by Led D5 and is on when Tx is enabled. Temp fault is indicated by Led D9 and is on when temperature is high. PSU fault is indicated by Led D36 and is on when power supply is faulty. RF fault is indicated by Led D7 and is on when RF power is low.
Page 28 FMT- 25 VHF FM TRANSLATOR 862-09725 Power supply and regulation: The power supply input to the RF PA Module is routed to a Switch-mode regulator, IC2. This is a 3Amp device with built-in current limiting and requires +24V minimum and +45V maximum. The output is set to +22.5V via R24/R25 .
Page 29: Maintenance Information
FMT- 25 VHF FM TRANSLATOR 862-09725 FMT-25 VHF FM TRANSLATOR TECHNICAL MANUAL Maintenance Information Issue 1A:...
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