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SBS PA250 Technical Manual

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PA250
POWER AMPLIFIER
TECHNICAL MANUAL

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Summary of Contents for SBS PA250

  • Page 1 PA250 POWER AMPLIFIER TECHNICAL MANUAL...

  • Page 2: Table Of Contents

    Information in this document is subject to change without notice and does not represent a commitment on the part of sbs. sbs shall not be liable for any direct, indirect, consequential or incidental damages as a result of the use or misuse of this equipment, handbook or any related materials.

  • Page 3: Introduction

    It is built to exceed the requirements of ETS 300 384: January 1995, Radio broadcasting systems standard for VHF FM sound broadcasting transmitters, specifying equipment for radio transmission. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 3...

  • Page 4: Safety, Electrical Hazard

    To ensure safety, it is the responsibility of the user to install and operate this equipment in a manner that is within the manufacturers specifications. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 4...

  • Page 5: Safety, Toxic Hazard

    UK your local council will have a toxic waste disposal department who will be able to advise you. Elsewhere you should contact the responsible authorities. NEVER DISPOSE OF A DEVICE CONTAINING BERYLLIUM OXIDE WITH GENERAL WASTE. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 5...

  • Page 6: Safety, Rf Hazard

    The permitted limits vary from country to country. Expert advice should be sought about the safe installation of any antenna system. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 6...

  • Page 7: Unpacking

    If any items are missing or damaged please inform your supplier immediately. Initial Checks Ensure that the PA250 has been set to the correct line voltage for your country. The standard version is set to 230V. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001...

  • Page 8: Controls And Connectors

    A small flat bladed trimmer tool is required to make this adjustment. The amplifier output power is not affected by this adjustment. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 8...
  • Page 9 100mA max. with an absolute maximum switched voltage of 30V. The interlock pins must be connected together for the PA250 power supply to operate. They should not be connected to any other point. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001...

  • Page 10: Installation

    If this air flow is restricted in any way the PA250 will have to operate at a higher internal temperature which may have a detrimental effect on its service life.

  • Page 11: Specifications

    -20°C to 45°C Humidity: 90% RH, non condensing Dimensions: 88 mm high (2U) x 443 mm wide x 420 mm deep, including handles and connectors, 12.5 kg weight PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 11...

  • Page 12: How To Contact Sbs

    Or fax 01424 443388 within the UK, +44 1424 443388 from outside the UK. Or email sales@sbs.uk.com for sales enquiries or support@sbsfm.com for technical support. Alternatively visit our web site: http://www.sbsfm.com/ PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 12...

  • Page 13: Technical Section Contents

    Technical Section Contents )))))))))))))))))))))))))))))))))) 10.1 Introduction 10.2 Circuit diagrams 10.3 Circuit description 10.4 Alignment 10.5 Fan replacement PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 13...

  • Page 14: Introduction

    10.1 Introduction )))))))))))))))))))))))))))))))))) The PA250 is internally divided into two sections. All RF circuitry is housed in a screened enclosure and is contained on two PTFE based PCBs, PAIN and PAOUT. The PAMASTER PCB is mounted outside of the RF section. It provides the power supply and all control and monitoring for the RF amplifier section.

  • Page 15: Circuit Diagrams

    10.2 Circuit diagrams )))))))))))))))))))))))))))))))))) PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 15...
  • Page 16 PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 16...
  • Page 17 PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 17...
  • Page 18 PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 18...
  • Page 19 PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 19...
  • Page 20 PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 20...

  • Page 21: Circuit Description

    A variable supply of 16 to 50V DC at up to 10A is generated by a buck or forward type converter. The RF output power of the PA250 is controlled through the adjustment of this supply to the RF amplifier. FET TR5 is the switching device.
  • Page 22 IC9 will command the P.FWD LED to turn red, driving through TR22 and TR23, and remove the P.FWD PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 22...
  • Page 23 RF power. The operation of the cutback is signalled by TR16 and TR17 driving the P. REF LED red and through TR18 flagging the failure on the P. REF OK line. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 23...

  • Page 24: Alignment

    6 amps. Use VR6 to calibrate the PA A range of the PA250'2 meter. Check temp sense Disconnect the temperature sensor from the sub PCB in the PA section. The fan speed should increase to PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 24...
  • Page 25 Check controls Verify that the external mute operates (link pin 19 to ground) and that the alarm signals are correct. PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 25...

  • Page 26: Fan Replacement

    Any replacement should be of the same type to ensure continued reliability. Replacing the fan is a simple process. If the equipment rack where the PA250 is installed has chassis supports (recommended) then it can be done without removing the amplifier from the rack.

  • Page 27: Declaration Of Conformity

    ETS 300 384:1995 Radio broadcasting systems; Very High Frequency (VHF), frequency modulated, sound broadcasting transmitters Signed: Date of Issue: On file 16 . 05. 2001 for and on behalf Pyers Easton of sbs, UK PA250 Pow er Amplifier Technical Manual © sbs. Release 31 May 2001 Page 27...

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