RKR Designs LLC Alpha 8410 User Manual
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RKR Designs LLC Alpha 8410 User Manual

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Alpha 8410 Linear Amplifier

User Manual

RKR Designs LLC
Document Issue 1.1
August 2015

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Summary of Contents for RKR Designs LLC Alpha 8410

  • Page 1: User Manual

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Document Issue 1.1 August 2015...

  • Page 2: Docnumber 8410 Document Issue

    632 S Sunset St Longmont CO 80501 303-473-9232 To reach technical support or obtain copies of this document, go to www.rksdesignsllc.com. Copyright © 2014 RKR Designs LLC. All rights reserved. Specifications subject to change without notice. DOCNUMBER 8410 Document Issue 1.1 Page ii...

  • Page 3: Table Of Contents

    Contents RKR Designs LLC Product Release 1 Contents 1. Introduction ........1-1 1.1 Product Description 1-1...
  • Page 4 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Contents Product Release 1 DOCNUMBER 8410 Document Issue 1.1 Page iv August 2015...
  • Page 5 List of Procedures List of Procedures Procedure 3-1, “Prepare your station,” page 3–1 Procedure 4-1, “Unpack the amplifier and transformer,” page 4–1 Procedure 4-2, “Connect the transformer,” page 4–2 Procedure 4-3, “Check the tubes and the exhaust chimney,” page 4–3 Procedure 4-4, “Connect the voltage tap,”...
  • Page 6 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC List of Procedures DOCNUMBER 8410 Document Issue 1.1 Page vi August 2015...

  • Page 7: Introduction

    1.1 Product Description 1–1 1.2 Product Capabilities 1–2 1.3 Safety Considerations 1–2 1.4 Related Products 1–3 1.5 Assistance 1–4 Congratulations on your purchase of a professional-quality Alpha 8410 linear amplifier. 1.1 Product Description The Alpha 8410 (see Figure 1-1) is a self-contained manual-tune HF linear power amplifier.

  • Page 8: Product Capabilities

    1.3 Safety Considerations • Locate the Alpha 8410 where there is good air circulation all around and on top of the cabinet. The unit may become hot during operation. • When moving the Alpha 8410, use proper lifting techniques and two people.

  • Page 9: Related Products

    This operating manual contains information, cautions, and warnings that you must follow to ensure safe installation and operation. Read Chapter 1 before attempting to unpack or operate the Alpha 8410. Failure to perform procedures properly may result in amplifier damage, fire hazard, or electric shock.

  • Page 10: Assistance

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Introduction 1.5 Assistance Technical assistance from RKR Designs is available from several sources. • Go to our website at www.rksdesignsllc.com and click Support. On this site you can get the following assistance: •...

  • Page 11: Amplifier Components And Specifications

    Amplifier components as photographed for this manual may differ from those in your amplifier, depending on your amplifier vintage. Remember The Alpha 8410 uses ceramic-and-metal forced-air-cooled tetrode vacuum tubes for amplification. The main power supply is an unregulated transformer/rectifier/capacitor power supply for the high-voltage (HV) and heater circuits.
  • Page 12 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Amplifier Components and Specifications The amplifier front, back, and interior are shown below (see Figure 2-1, Figure 2-2, and Figure 2-3). Amplifier components are listed alphabetically and described below. Figure 2-1...

  • Page 13: Boards

    RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Amplifier Components and Specifications Figure 2-3 Amplifier interior (components may differ from those in your amplifier, depending on its vintage) 2.1 Boards The following amplifier boards are described below in alphabetical order: •...

  • Page 14: Control Board

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Amplifier Components and Specifications IMPORTANT Do not defeat this safety circuit. It is placed there for your protection. Control Board The control board is the heart of the amplifier. It is based on a PIC microcontroller.
  • Page 15 RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Amplifier Components and Specifications Mains Board Power-supply functions are split between the mains board and the HV board. The mains board deals mostly with the primary side of the transformer. The various taps for the transformer primary are routed through this board and so is the AC line input.

  • Page 16: Controls And Display

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Amplifier Components and Specifications 2.2 Controls and Display The Alpha 8410 controls enable you to adjust and monitor the amplifier as needed (see Table 2-1). Table 2-1 Amplifier controls Control Purpose...

  • Page 17: Specifications

    The tube sockets contain the integral screen grid (grid 2) RF bypass capacitors as well as contacts for the screen, heater, and filament of the tubes. 2.5 Specifications The Alpha 8410 linear amplifier specifications are as follows. Table 2-2 Alpha 8410 linear amplifier specifications Parameter...
  • Page 18 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Amplifier Components and Specifications (Continued) Table 2-2 Alpha 8410 linear amplifier specifications Parameter Value Intermodulation level 30 dB minimum, two exciter Harmonics –50 dBc Mode of operation CW, SSB, FM Input AC voltage...

  • Page 19: Preparing Your Station

    3.2 Limitations of Operation at Nonstandard Voltage 3–4 3.1 Prepare Your Station The Alpha 8410 is capable of dramatically improving the performance of your amateur station. It is important that you observe good engineering practices to achieve all the benefits of such a station in a safe and reliable manner.
  • Page 20 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Preparing Your Station It is critical that airflow around the amplifier remain unimpeded at all times and that the top of the amplifier remain clear of any restrictions. Maintain at least 3 in. of clearance around the amplifier and at least 4 in.
  • Page 21 RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Preparing Your Station Support the coax frequently using noncompressive clips so that it does not hang or stretch under its own weight. Avoid sharp or kinked bends (most manufacturers specify a minimum bend radius for their product).

  • Page 22: Limitations Of Operation At Nonstandard Voltage

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Preparing Your Station 3.2 Limitations of Operation at Nonstandard Voltage Electrical-power equipment draws twice as much primary current from 120-V mains as from 240-V mains. Therefore, if you operate the Alpha 8410 on typical 120-V/20-A household circuit without exceeding the 20- A circuit rating, you limit maximum peak power output to ~600–1000 W.

  • Page 23: Setting Up The Amplifier

    4.7 Connect the Transceiver Keying Line 4–7 IMPORTANT The Alpha 8410 is easy to set up, tune, operate, and maintain. However, failure to carry out each procedure exactly as described in this manual is likely to lead to amplifier damage, which is not covered under warranty.

  • Page 24: Connect The Transformer

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Setting Up the Amplifier 4.2 Connect the Transformer • NOTE The transformer is very heavy. When moving it, use due caution and handle only by the lifting handle. • Do not over-tighten the screws that hold the transformer in place, as doing so may cause excessive vibrations or noise.

  • Page 25: Check The Tubes And Exhaust Chimney

    RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Setting Up the Amplifier CAUTION CAUTION! Do not use the transformer’s shipping bolts. They are too long and will damage the transformer! 4.3 Check the Tubes and Exhaust Chimney With the amplifier cover removed, check and, if necessary, adjust the tubes and the exhaust chimney.

  • Page 26: Connect The Cables

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Setting Up the Amplifier Figure 4-1 Amplifier power settings Procedure 4-4 Connect the voltage tap Step 1 Ensure that the amplifier is unplugged. Step 2 Move the flying lead to the AC spade post marked with the appropriate voltage.
  • Page 27 RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Setting Up the Amplifier WARNING WARNING! To avoid the hazard of a potentially fatal electric shock and/or severe damage to the amplifier and other equipment: • NEVER operate the amplifier with the cover removed.

  • Page 28: Set The Input-Drive Power

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Setting Up the Amplifier The amplifier’s relay jack has ~12 V on it. When pulled all the way to ground, a current of 10 mA flows. For information on how to connect to an external amplifier, see your transceiver manual.

  • Page 29: Connect The Transceiver Keying Line

    RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Setting Up the Amplifier Some transceivers may produce RF spikes upon keying during SSB operations. Do not operate the amplifier with transceiver power controls set at full power output. Do not rely on the mic gain control to set power.
  • Page 30 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Setting Up the Amplifier DOCNUMBER 8410 Document Issue 1.1 Page 4–8 August 2015...

  • Page 31: Operating The Amplifier

    5.4 Operate the Amplifier 5–7 5.1 Principles of Operation Once your Alpha 8410 linear amplifier is set up as described in the previous chapters, before first use you must tune it for peak RF output and lowest current for the selected antenna port over the range of band segment frequencies to be used.

  • Page 32: Start Up The Amplifier

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Operating the Amplifier Table 5-1 Operational states (Continued) State Description Standby Tubes are ready and amplifier is in bypass mode (exciter only). To enter this state: Wait for the amplifier to complete its 3-minute warmup.

  • Page 33: Tune The Amplifier

    5–3. 5.3 Tune the Amplifier Each Alpha 8410 shipped from the factory includes a table showing the tune and load settings that we used to achieve full output power on that particular amplifier into an AP 2100 50-ohm dummy load. These settings usually vary slightly from those in this guide.
  • Page 34 SWR; in fact, you lose power this way. The Alpha 8410 senses the beginning of any RF arc in, for example, a TUNE or LOAD variable capacitor and automatically switches the amplifier to standby within a few milliseconds.This system has virtually...
  • Page 35 RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Operating the Amplifier 4. Turn the OPR/STBY switch to OPR. Proceed with the tuning procedure Tuning by the This is our recommended way to tune the amplifier. Recommended Dip- and-Load Method...
  • Page 36 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Operating the Amplifier Step 2 Set the BAND, TUNE, and LOAD controls to the values given in your amplifier’s specific tuneup table. Note that final TUNE and LOAD settings will vary with operating frequency, antenna characteristics, and power level.

  • Page 37: Operate The Amplifier

    RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Operating the Amplifier 5.4 Operate the Amplifier Procedure 5-4 Operate the amplifier Step 1 Start up and tune the amplifier as described in “Start Up the Amplifier,” page 5–2 “Tune the Amplifier,” page 5–3.
  • Page 38 Idling plate current for the Alpha 8410 is ~350–400 mA during full-power transmission. A detector senses RF drive, and, during pauses in speech and key-up intervals, reduces plate current to 30–50 mA, substantially...

  • Page 39: Maintaining The Amplifier

    6.3 Retune the Amplifier 6–3 IMPORTANT • The Alpha 8410 is extremely easy to set up, operate, and maintain. However, failure to carry out each procedure exactly as described in this manual is likely to lead to amplifier damage, which is not covered under warranty. Damage to other station equipment may also result.

  • Page 40: Replace Tubes And/Or Fuses

    Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Maintaining the Amplifier WARNING WARNING! Do not allow any liquids to enter the cover’s tube- exhaust holes. Step 3 Disconnect the AC line cord from the power source and lift the cover.

  • Page 41: Step 5

    RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Maintaining the Amplifier use of a fuse of incorrect size or type is not covered under and may void the warranty. Blowing of one or both primary-line fuses indicates that the maximum safe average power capability of the amplifier has been substantially exceeded or that an equipment failure has occurred.
  • Page 42 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Maintaining the Amplifier DOCNUMBER 8410 Document Issue 1.1 Page 6–4 August 2015...

  • Page 43: Diagnosing Faults And Troubleshooting

    Diagnosing Faults and Troubleshooting 7.1 Diagnose Faults 7–1 7.2 Troubleshoot Problems 7–4 7.1 Diagnose Faults If the amplifier encounters unsafe operating conditions, it enters a protective fault mode and faults into STBY or OFF. The OPR LED goes off and the FAULT and STBY LEDs go on. When this happens, the tubes are biased off and the relays are placed in bypass mode, causing RF from the radio to go directly to the antenna.
  • Page 44 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Diagnosing Faults and Troubleshooting Fault type 1 Both Ip and HV LEDs are blinking. LED behavior Amplifier gain has fallen to <10 dB. Cause This is an important safety feature of the amplifier, as many different problems can be detected as a drop in gain.
  • Page 45 RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Diagnosing Faults and Troubleshooting 1. Check the output coaxial cable and connectors; replace or reconnect Resolution as needed. 2. Check the antenna SWR using an external wattmeter or by putting the amplifier in standby mode and using the SWR meter on your transceiver.
  • Page 46 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Diagnosing Faults and Troubleshooting the amplifier back on. Doing so is likely to result in severe damage to amplifier components. 2. If the plate current again starts to rise while the amplifier is warming up, investigate and resolve the problem before attempting to turn the amplifier on again.
  • Page 47 RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Diagnosing Faults and Troubleshooting The plate voltage to the power supply may be too low. Check the line Amplifier turns on but HV reading is low as indicated on voltage and confirm that the tap is set correctly.
  • Page 48 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Diagnosing Faults and Troubleshooting 2. The transceiver may be locked in transmit. Ensure that the transceiver is properly switching between TRANSMIT and RECEIVE modes. For assistance, see the transceiver manual. The tube bias supply or T/R bias switch may be faulty. Contact RKR...

  • Page 49: Docnumber 8410 Document Issue

    Terminology Terminology NOTE: For detailed explanations of the following terms, see various publications including the latest American Radio Relay League (ARRL) Handbook. AB1 — ampere — Modulation class AB1. Class that provides Unit of electric current. good linearity in a push-pull configuration. ARRL —...
  • Page 50 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Page Terminology EBS — exciter — Electronic bias switching. A form of Radio that provides RF drive for the switching that increases negative grid 1 voltage amplifier to operate. The transmitter portion of in pauses in speech or between Morse code the transceiver.
  • Page 51 RKR Designs LLC Alpha 8410 Linear Amplifier User Manual Terminology LED — LV — Light-emitting diode. Semiconductor Low voltage. Electrical circuit in which the diode that emits incoherent narrow-spectrum voltage used presents risk of electric shock but light, providing a form of electroluminescence.
  • Page 52 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Page Terminology SSB — STBY — Single sideband. Modulation scheme that Standby. Mode in which an electronic refines upon amplitude modulation. appliance is turned off but under power and ready to activate on command.
  • Page 53 Schematics Schematics NOTE: The following pages contain detailed schematics for the Alpha 8410 linear amplifier. DOCNUMBER 8410 Document Issue 1.1 August 2015 Page Schem–1...
  • Page 54 Alpha 8410 Linear Amplifier User Manual RKR Designs LLC Page Schematics DOCNUMBER 8410 Document Issue 1.1 Page Schem–2 August 2015...

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