Alpha 8410 User Manual
Contents
1. 2 6 0 2 a a 5 1 5 1 Principles of Operation 5 1 5 2 Start Up the Amplifier 5 2 5 3 Tune the Amplifier 5 3 5 4 Operate the Amplifier 5 7 6 Maintaining the Amplifier 1 2 ee ee 6 1 6 1 Clean the Amplifier Chassis 6 1 6 2 Replace Tubes and or Fuses 6 2 6 3 Retune the Amplifier 6 3 7 Diagnosing Faults and Troubleshooting 7 1 7 1 Diagnose Faults 7 1 7 2 Troubleshoot Problems 7 4 Terminology Term 1 Schematics Schem 1 DOCNUMBER 8410 T ___ _rr Document Issue 1 0 March 2014 Page ili Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Contents Product Release 1 DOCNUMBER 8410 Document Issue 1 0 Page iv March 2014 List of Procedures List of Procedures DOCNUMBER 8410 Document Issue 1 0 March 2014 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 44 Procedure 4 5 Connect the cables page 4 4 Procedure 4 6 Connect the transceiver keying line page 4 7 Procedure 5 1 Start up the amplifier page 5 2 Procedure 5 2 Tune by the recommended dip and load method page 5 5 Procedure 5 3 Tune by the alternate nominal gain method page 5 5 Procedure 5 4 Operate the amplifier page 5 72. Do the following Ta Adjust the TUNE control to deflect the GAIN LED maximum rightward 7b Adjust the LOAD control to place the illuminated GAIN LED between the white lines above and below the LED bargraph Repeat this step at least twice Increase the excitation power until the amplifier output is 1500 W Do the following 9a Adjust the TUNE control to deflect the GAIN LED maximum rightward 9b Adjust the LOAD control to place the illuminated GAIN LED between the white lines above and below the LED bargraph Touch up the TUNE control for maximum power output The amplifier is now correctly tuned to deliver 1500 W RF output on SSB CW FSK SSTV and FM The GAIN LED normally fluctuates during modulation or keying If the first red LED on the RF OUTPUT bargraph lights output exceeds 1500 W It is normal for the GAIN LED to vary during standard operation especially for SSB Proceed to Operate the Amplifier page 5 7 DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC Alpha 8410 Linear Amplifier User Manual Operating the Amplifier 5 4 Operate the Amplifier Step 1 Step 2 Step 3 Step 4 Step 5 DOCNUMBER 8410 Document Issue 1 0 March 2014 Procedure 5 4 Operate the amplifier Start up and tune the amplifier as described in Start Up the Amplifier page 5 2 and Tune the Amplifier page 5 3 Apply RF The amplifier requires only 50 W for full output Ensure that
3. Page 4 6 You must set the transceiver output power properly Virtually all damage to date has resulted directly from severe overdrive The amplifier requires 50 W drive for full rated output Damage caused by applying several times rated drive power to the amplifier is not covered under warranty Fortunately most modern transceivers maintain quite consistent output from band to band and mode to mode when set up properly DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts 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 Rather set up the transceiver with proper mic gain and processor levels at normal power level to drive the amplifier typically 50 W CAUTION It is not sufficient to set only the transceiver POWER or RF PWR control Several popular transceivers can generate RF spikes of 200 300 W Control these spikes with a knob labeled DRIVE IC 781 FT 1000 or PROCESSOR OUT TS 940 T5 950 On SSB when you are not using speech processing adjust the MIC or MIKE controls For more information see the manual for your particular transceiver 4 7 Connect the Transceiver Keying Line DOCNUMBER 8410 Document Issue 1 0 March 2014 Step 1 Procedure 4 6 Connect the transceiver keyi
4. A 4 AS j di 7 Input AC safety switch A Transformer relay HV AC transformer amp AC tap board The following amplifier boards are described below in alphabetical order e Center partition board e Control board e Display board e HV board e Mains board e Transmit receive T R board e Tube deck board Center Partition Board The center partition board contains the RF decoupling circuit on the B line as well as the crowbar safety circuit When you remove the top cover of the amplifier the spring metal of this safety device shorts out the B line Do not defeat this safety circuit It is placed there for your protection Page 2 3 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Amplifier Components and Specifications Control Board The control board is the heart of the amplifier It is based on a PIC microcontroller This microcontroller has a built in multichannel analog to digital converter that monitors all critical voltages and currents in the amplifier as well as the input power and output forward and reflected power It uses these converted values to control the amplifier s operation and to drive the display board on the front panel A USB port on the back of the amplifier is provided for remote monitoring The USB driver for the amplifier is provided on the CD that ships with the amplifier or is available at www rfconcepts com Display Board The display board uses a MAX7219 LED d
5. Page 5 7 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Operating the Amplifier Page 5 8 NOTE In the event of grossly excessive plate current or fault in the high voltage circuitry the plate current relay quickly turns the amplifier off However the relay does not prevent tube or other damage due to either short term or long term overdrive or improper tuning It is your responsibility to ensure safe tuning drive and general operating conditions If the overcurrent relay trips remove AC power from the amplifier then determine and correct the cause of the trip before turning the amplifier back on This hard fault trip circuit does not rely on the microcontroller for its operation and protects the amplifier under all conditions even if the processor is damaged or malfunctioning 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 reducing average power supply loading heat generation and wasted energy If the amplifier faults it usually resets itself after 4 seconds For information about faults see Chapter 7 Diagnosing Faults and Troubleshooting DOCNUMBER 8410 Document Issue 1 0 March 2014 6 Maintaining the Amplifier 6 1 6 2 6 3 IMPORTANT Clean the Amplifier Chassis 6 1 Replace Tubes and or Fuses 6 2 Retune the Ampl
6. Step 5 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 Ensure that the connection from feed line to antenna is waterproof Provide for disconnection of the feed line when it is not in use This protects against damage caused by wind static and lightning strikes which are not covered under the amplifier warranty The importance of a well constructed feed line system cannot be overstated The purpose of the amplifier is to provide approximately 2 S units 12 dB of improvement in your radiated signal Cheap poor or underrated coax and connectors can degrade performance by at least one S unit This means that you could have bought a 375 W amplifier and achieved the same radiated signal by buying good quality feed line components Never use old coax which may have had moisture penetrate under the jacket NOTE The FCC requires users to check their installations for compliance with published values for allowable exposure to RF fields This information is available in ARRL publications FCC printed rules and on the web We strongly recommend that you do this for any installation both fixed and at an expedition or contest site If you have any questions regarding engineering your amplifier into your amateur radi
7. Never replace a fuse with one of a different type or greater current rating Damage resulting from DOCNUMBER 8410 Document Issue 1 0 Page 6 2 March 2014 RF Concepts LLC Step 5 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 The slow blow fuse F3 located below the primary line fuses may prevent damage to the step start resistors and HV rectifiers in the event of abnormal turn on conditions or HV faults If the AC interlock is defeated and primary power is applied while the HV crowbar is closed the step start fuse normally blows Replace the cover and reconnect the AC line cord to the power source 6 3 Retune the Amplifier DOCNUMBER 8410 Document Issue 1 0 March 2014 Normally you need to retune the amplifier only if you change radios antennas or some other aspect of your shack Your objective in tuning the amplifier and the drive applied to it is to obtain optimum efficiency and linearity at the desired output power You must adjust the amplifier for optimum efficiency and linearity at each specific power level If you attempt to operate at higher or lower power levels than those for which you have adjusted the following
8. Procedure 6 1 Clean the amplifier chassis page 6 1 Procedure 6 2 Replace tubes and or fuses page 6 2 Page v Alpha 8410 Linear Amplifier User Manual RF Concepts LLC List of Procedures DOCNUMBER 8410 Document Issue 1 0 Page vi March 2014 1 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 DOCNUMBER 8410 Document Issue 1 0 March 2014 The Alpha 8410 see Figure 1 1 is a self contained manual tune HF linear power amplifier It is capable of continuous operation at 1500 W peak power output on single sideband SSB keyed continuous wave CW slow scan television SSTV radioteletype RTTY digital modes or FM with no time limit CAUTION Study this manual carefully before operating your amplifier for the first time In particular it is extremely important that you thoroughly review the installation and operation sections Failure to do so could result in serious damage not covered under warranty Page 1 1 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Introduction Figure 1 1 Alpha 8410 ALPHA 8410 HF UNERA AMPUFIER 1 2 Product Capabilities Product capabilities include e Continuous RF output The Alpha 8410 is capable of 1 5 kW continuous RF output on all comm
9. voltage used presents risk of electric shock but only minor risk of electrical arcing MHz Megahertz 10 Hz PCB Printed circuit board Board that mechanically supports and electrically connects electronic components changes or modulations in the phase of a reference signal Switches to receive between each dot or dash allowing the operator to hear any signal being sent RMS Root mean square Statistical measure of the magnitude of a varying quantity such as a wave RTTY Radio teletype Telecommunications system consisting of two or more teleprinters using radio as the transmission medium Page Term 3 Alpha 8410 Linear Amplifier User Manual Page Terminology S SSB Single sideband Modulation scheme that refines upon amplitude modulation SSTV Slow scan television Picture transmission method for transmitting and receiving static pictures via radio T T R Transmit receive U UHF Ultra high frequency Radio frequency within the range 300 3000 MHz 3 GHz V VAC Volts of alternating current VDC Volts of direct current Page Term 4 RF Concepts LLC STBY Standby Mode in which an electronic appliance is turned off but under power and ready to activate on command SWR Standing wave ratio Ratio of the amplitude of a partial standing wave at an antinode maximum to the amplitude at an adjacent node minimum Measure of antenna and feedline
10. 1 5 Assistance Technical assistance from RF Concepts is available from several sources e Go to our website at www rfconcepts com and click Support On this site you can get the following assistance e Alpha Forum e FAQs e Legacy equipment information e Manuals e Repair information e Software downloads e Tech tips e Technical support e E mail us by completing a support request at rfconcepts com e Fax us at 303 473 9660 e Phone us at 303 473 9232 DOCNUMBER 8410 Document Issue 1 0 Page 1 4 March 2014 2 Amplifier Components and Specifications DOCNUMBER 8410 Document Issue 1 0 March 2014 2 1 Boards 2 3 2 2 Controls and Display 2 6 2 3 Output Tank Circuit 2 6 2 4 Tubes and Tube Deck 2 6 2 5 Specifications 2 7 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 All other power supplies are regulated The control circuit uses a microprocessor in the loop to monitor and control amplifier operation There are seven circuit boards in the amplifier e Center partition board e Control board e Display board e HV board e Mains board e Transmit receive T R board e Tube deck board In addition to these the tubes tank circuit assembly and transformer complete the main sections of the amplifier These major blocks are described belo
11. all antennas are rated for 1500 W and that they are carefully tuned and installed for minimum voltage SWR Many antennas that are suitable for general use are unsuited for operation at full 1500 W power At this power level in a 50 ohm circuit the RMS current is 5 5 A and the peak RF voltage is 387 V For SWR 2 1 these values double to 11 A and 775 V The actual voltage and current at various points in or on your antenna may actually be many times these values On a simple dipole with sharp wire ends corona localized ionization can easily occur Corona can and has led to fire in nearby objects Traps in beams and verticals can heat up significantly during high power operation Melting or flashover of traps have occurred in many installations where insufficient thought has been given to their ratings If an antenna has been deployed for a long period of time take it down for inspection before full power operation If any insulators are cracked or show signs of tracking replace them Provide adequate RF cabling Use good quality low loss coaxial cable Use new clean connectors and install them according to manufacturer recommendations Clean the connectors after soldering them and before mating them with the amplifier Remove any excess solder from the connector likewise remove any fragments of braid and the like DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC DOCNUMBER 8410 Document Issue 1 0 March 2014
12. efficiency transceiver Device that has both a transmitter and a receiver within the same circuitry or chassis US United States VSWR Voltage standing wave ratio Example If VSWR 1 2 1 the maximum standing wave amplitude is 1 2 times greater than the minimum standing wave amplitude DOCNUMBER 8410 Document Issue 1 0 March 2014 Schematics Schematics NOTE The following pages contain detailed schematics for the Alpha 8410 linear amplifier DOCNUMBER 8410 Document Issue 1 0 March 2014 Page Schem 1 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Page Schematics DOCNUMBER 8410 Document Issue 1 0 Page Schem 2 March 2014
13. exhaust air is detectable from the exit vent holes above the tube If exhaust air is not detectable 3a TURN OFF the amplifier immediately 3b Ensure that the exhaust chimneys are properly positioned over the tubes 3C Power up the amplifier again 3d When the WAIT LED goes out and the OPR or STBY lights stop blinking indicating that warmup is complete move the OPR STBY switch to OPR Monitor grid current The amplifier operates in Class ABI when delivering maximum output power consistent with excellent linearity A small amount of grid current flows which you can monitor as follows e The GRID MIN LED lights up green as drive approaches the optimum level e The GRID LED flickers green on SSB voice peaks and lights up under CW SSTV RTTY carrier conditions e The GRID MAX LED does the following e Lights dim red at maximum output and efficiency e Lights full red as overdrive approaches For SSB operation optimum output consistent with good linearity occurs when the GRID LED lights up green on most voice peaks and the GRID MAX LED flickers dim red on only the highest peaks Excessive grid current results from overdrive and or inadequate loading The solution is to restrict drive and or increase amplifier loading The amplifier s VTX X118 tubes are well protected and these adjustments tend to be less critical than in many other amplifiers Grid bias is stabilized against grid current fluctuations Monitor plate current
14. happens e At higher power the amplifier flattops splatters and usually produces excessive amplifier grid current e At lower power the amplifier decreases efficiency considerably For instructions on retuning the amplifier see Section 5 3 Tune the Amplifier page 5 3 Page 6 3 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Maintaining the Amplifier DOCNUMBER 8410 Document Issue 1 0 Page 6 4 March 2014 r Diagnosing Faults and Troubleshooting 7 1 Diagnose Faults DOCNUMBER 8410 Document Issue 1 0 March 2014 7 1 Diagnose Faults 7 1 7 2 Troubleshoot Problems 7 4 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 The FAULT LED on the front panel flashes on and off for 4 seconds After this period unless the OPER STBY switch has been placed in the STBY position the amplifier attempts to return to OPERATE mode You can shorten this 4 s period by toggling the OPER STBY switch While the FAULT LED 1s flashing the Ip and HV LEDs indicate which fault type caused the amplifier to enter fault mode Fault type codes are also reported in the amplifier telemetry data via the USB port on the rear of the amplifier These fault types are s
15. midrange voltage for each tap is printed on the mains board circuit board The acceptable line voltage for each tap is the center voltage plus or minus 10 V Never use a tap other than the proper voltage or damage to the tube and amplifier will result 4 5 Connect the Cables Procedure 4 5 Connect the cables Step 1 The amplifier ships from the factory with a power cord and plug If you ever need to change them perform this step DOCNUMBER 8410 Document Issue 1 0 Page 4 4 March 2014 RF Concepts LLC Step 2 Step 3 Step 4 DOCNUMBER 8410 Document Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual Setting Up the Amplifier WARNING To avoid the hazard of a potentially fatal electric shock and or severe damage to the amplifier and other equipment e NEVER operate the amplifier with the cover removed e ALWAYS use an AC plug that is appropriate for the primary mains voltage current rating and configuration e ALWAYS use grounding type AC connectors that conform to local codes e NEVER use 120 VAC plugs to connect to power receptacles for 190 250 V circuits e ALWAYS connect ALL station equipment to a good common ground Failure to do so may allow RF feedback to leak into the transceiver and cause severe signal distortion 1a Connect the green wire in the amplifier power cable only to the AC mains safety ground or to neutral as may be necessary with a 240 V circuit configured 120V N 120V w
16. slightly increase LOAD for a peak in RF out then peak RF out with TUNE control When the amplifier is tuned correctly on 160 through 40 m the following should be the case e The Ip should range between 0 9A and 1 1 A read on the 0 1 5 A scale for 1500 W output e The input drive power should not be more than 60 W e On 20 m the Ip is usually 1 0 A for 1500 W output Plate current Ip is the most useful parameter to monitor on the multimeter bargraph during normal operation Proceed to Operate the Amplifier page 5 7 This is an alternative way to tune the amplifier Procedure 5 3 Tune by the alternate nominal gain method Start up the amplifier as described in Start Up the Amplifier page 5 2 Page 5 5 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Operating the Amplifier Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10 Step 11 Page 5 6 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 Reduce the transceiver carrier output control to 0 Move the OPR STBY switch to OPR operate The OPR LED lights up On the multimeter selector switch bargraph select the GAIN function Switch the transceiver to CW and increase its carrier output to 15 W the amplifier output will be 300 500 W
17. the back of the amplifier 2 Confirm that the key line is connected to the correct port on the transceiver and that amplifier keying is enabled 3 If the tube current has exceeded 2 5 A follow the resolution instructions for Fault type 2 page 7 2 and Fault type 5 page 7 3 4 Confirm that the cable is good 5 Confirm with the multimeter switch in the Ip position and the amplifier keyed with no RF that plate current is drawn The tube current may exceed 2 5 A See the resolution instructions for Fault type 4 page 7 3 The amplifier may be overdriven or incorrectly tuned most likely the load control is set too low Reduce the transceiver output and adjust the tune and load controls to maximize efficiency with minimum grid lights 1 The RELAY T R control cable from the transceiver may be shorted Check the cable to ensure that it is switching properly Replace it if needed Page 7 5 Alpha 8410 Linear Amplifier User Manual RF Concepts 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 When amplifier isin STBY or The tube bias supply or T R bias switch may be faulty Contact RF RECEIVE mode plate current Concepts technical support is indicated Distorted SSB signal grid 1 The RF drive from the transceiver may be excessive and or a
18. 8410 can be in one of seven operational states listed in Table 5 1 Table 5 1 Operational states State Description Off Plugged in but OFF To enter this state Plug the amplifier into the AC line supply In this state The front panel is dark The internal auxiliary 5 V power supply is on The microprocessor is powered up and communicates via the USB port On warmup Tube is warming up and HV is present To enter this state Press the ON OFF switch to ON In this state The AC line is connected to the primary of the transformer and all amplifier voltages are present including the high voltage for the tubes A 3 minute warmup countdown begins with LEDs lighting up sequentially along the RF OUTPUT bargraph The amplifier cannot be switched to Operate until the countdown timer reaches 0 The number of seconds remaining is displayed in the serial data During warmup we recommend that you check the plate voltage by rotating the multimeter selector switch to HV The LED bargraph should show 3 kV DOCNUMBER 8410 Document Issue 1 0 March 2014 Page 5 1 Alpha 8410 Linear Amplifier User Manual RF Concepts 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 In this state The exciter can use the antenna but the amplifier does not amplify the sig
19. RF Concepts Alpha 8410 Linear Amplifier User Manual www rfconcepts com Documen t Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Alpha 8410 Linear Amplifier User Manual RF Concepts LLC 632 S Sunset St Longmont CO 80501 303 473 9232 Prepared for RF Concepts by MH GP LW To reach technical support or obtain copies of this document go to www riconcepts com Copyright 2014 RF Concepts LLC All rights reserved Specifications subject to change without notice DOCNUMBER 8410 Document Issue 1 0 Page ii March 2014 RFC ts LLC product FIESRE 1 Co nie n ts Contents RIMORSO TETI E 1 1 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 2 Amplifier Components and Specifications 2 1 2 1 Boards 2 3 2 2 Controls and Display 2 6 2 3 Output Tank Circuit 2 6 2 4 Tubes and Tube Deck 2 6 2 5 Specifications 2 7 3 Preparing Your Station 1 ee 3 1 3 1 Prepare Your Station 3 1 3 2 Limitations of Operation at Nonstandard Voltage 3 4 4 Setting Up the Amplifier 2 0 2 0 0 002 ee ene 4 1 4 1 Unpack the Amplifier and Transformer 4 1 4 2 Connect the Transformer 4 2 4 3 Check the Tubes and Exhaust Chimney 4 3 4 4 Connect the Voltage Tap 4 3 4 5 Connect the Cables 4 4 4 6 Set the Input Drive Power 4 6 4 7 Connect the Transceiver Keying Line 4 7 5 Operating the Amplifier
20. STBY switch to STBY 3 Verify all connections and cables DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC Tuning by the Recommended Dip and Load Method Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Tuning by the Alternate Nominal Gain Method Step 1 DOCNUMBER 8410 Document Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual Operating the Amplifier 4 Turn the OPR STBY switch to OPR 5 Proceed with the tuning procedure This is our recommended way to tune the amplifier Procedure 5 2 Tune by the recommended dip and load method Start up the amplifier as described in Start Up the Amplifier page 5 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 Please limit the transceiver drive to 65 W for tuning and operating the amplifier Move the multimeter selector switch to Ip plate current Set the TUNE and LOAD controls to the values given in your amplifier s specific tuneup table Key the amplifier with 20 W drive and adjust the TUNE control for a peak in RF out that should be at the same point as a dip in Ip Increase the drive to get 1000 W output going back and forth between TUNE and LOAD to peak the RF output If more output is desired increase drive from the amplifier
21. 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 WARNING Disconnect the AC line cord from the power source before lifting the cover for any reason Step 4 Clean the interior particularly high voltage areas with a vacuum cleaner and a soft bristle brush frequently enough to prevent visible accumulation of dust Optimally remove the plate under the tube deck attached with 4 screws and use compressed air to blow out the cooling fins in the tubes Step 5 If conditions are extremely dusty secure a thin air filter of the type used for window air conditioners across the air intake on the rear panel Step 6 Replace the cover and reconnect the AC line cord to the power source 6 2 Replace Tubes and or Fuses Perform this procedure only as needed Procedure 6 2 Replace tubes and or fuses Step1 Power down the amplifier Step 2 Disconnect the AC line cord from the power source and lift the cover WARNING Before lifting the cover for any reason disconnect the AC line cord from the power source Step 3 Replace tubes as needed Ensure that cooling airflow to the tubes is sufficient Use a matched pair of high quality VT X X118 tubes Step 4 Replace fuses as needed For 190 220 V AC service use only 20 A 250 V rated fuses For 90 130 VAC service you may optionally use 25 A fuses with caution IMPORTANT
22. antenna tuner The SWR can be tuned via the antenna or an external tuner connected to the amplifier output Nevertheless at SWR of lt 2 1 the additional RF power loss of an antenna tuner can be avoided by tuning the amplifier into the slight mismatch There is no advantage to using a tuner to tweak the last bit of 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 eliminated RF arc damage in current Alpha amplifiers The system similarly detects severe mistuning and if drive exceeds 25 W switches the amplifier to standby The 25 W input trip threshold permits safe tuning at low power levels without aggravating and unnecessary trip outs A properly tuned amplifier has the following properties e Full legal power output For voltage SWR lt 2 0 1 normal value is 1500 W with 40 60 W drive For SWR gt 2 0 1 full output may not be possible but the other tuning indications are the same e Grid current green LED either lit or unlit e Gain indication in right half of bargraph e Plate current normal value of 1 A at 1500 W The system alarms at values exceeding 1 2 A CAUTION If at any time in the following procedure the amplifier fails to respond as described do the following 1 Remove drive immediately 2 Turn the OPR
23. as and provides negative feedback which improves linearity and hence intermodulation distortion IMD performance Electronic bias switching EBS increases the negative grid 1 voltage in pauses in speech or between Morse code elements This reduces the standing bias on the tubes resulting in less waste heat longer tube life and higher overall amplifier efficiency The artifacts of EBS are not noticeable under normal communications conditions The tubes are operated as a swamped grid tetrode design The tube grids are tied at RF to a 50 ohm swamping resistor that absorbs most of the input drive power The RF voltage across this resistor is added to the grid 1 DC bias to provide the net low impedance tube grid bias The RF impedance represented by grid 1 and its capacitance is compensated for by a series inductance to provide SWR lt 2 1 on each band at the amplifier s input At higher frequencies a relay switches in a separate matching network This relay is under microprocessor control and is actuated according to the band To prolong tube life refrain from cycling AC power on off on off repeatedly It is less stressful to leave equipment in standby for several hours than to cycle it on and off repeatedly The tube deck is a mechanical assembly enclosing the tube sockets and the tube deck board The tube sockets contain the integral screen grid grid 2 RF bypass capacitors as well as contacts for the screen heater and filament o
24. c topology is pi L which provides harmonic attenuation adequate to meet the requirements of all countries globally that permit power outputs of 1500 W Band switching is under manual control accomplished by a 4 wafer band switch These wafers are used as multifunction tap selectors which simultaneously select band taps on the inductors and include varying amounts of capacitance to provide band spread on the tune and load capacitors The wafers are in the RF tank area A variable resistor inside the front subchassis is used by the control board to determine which band you have selected 2 4 Tubes and Tube Deck The amplifier uses two 4CX1000A Alpha part number VTX X118 tetrode tubes operating well within their ratings and in parallel The tubes are very rugged and normally operate with a large margin of safety They should provide outstanding service for many years if they are not damaged by abuse such as overdrive or blockage of cooling airflow DOCNUMBER 8410 Document Issue 1 0 Page 2 6 March 2014 RF Concepts LLC NOTE 2 5 Specifications Alpha 8410 Linear Amplifier User Manual Amplifier Components and Specifications The tubes are operated in Class AB1 with a plate voltage of 2800 V nominal full output key down a grid 1 voltage of 50 to 60 minus 50 to minus 60 V and a grid 2 voltage of 200 V They have a low inductance resistor in series with their cathodes This resistor stabilizes the tube bi
25. ed behavior For a line voltage of lt 120 V do not expect to be able to get 1500 W output For maximum efficiency tune the amplifier for no more than 1000 W output For a line voltage of 110 130 V 1500 W PEP operation CW or SSB may be possible 1f your AC line service has sufficient current capacity 30 A circuit recommended However 1500 W continuous should not be expected Tube lifetimes may be reduced Ask your utility company 1f they can reduce your line voltage If this is not possible consider placing your own step down transformer in line between the AC outlet and the amplifier A transformer with at least 4 kVA rating is required due to the nature of the current waveform in the primary Another choice for voltage control a ferroresonant voltage regulator is an expensive solution but is a good way to stabilize primary voltage If you intend to operate the amplifier at 120 V or if other equipment D draws current from the same circuit as the amplifier the following 1 Ensure that the AC cord is not coiled too tightly or placed where normal air flow is restricted causing it to overheat 2 Change the lower 2 A fuse on the rear panel to a 5 A fuse to allow for the increased in rush current Page 3 4 DOCNUMBER 8410 Document Issue 1 0 March 2014 4 Setting Up the Amplifier IMPORTANT 4 1 Unpack the Amplifier and Transformer 4 1 4 2 Connect the Transformer 4 2 4 3 Check the Tubes and Exhaust Chimn
26. ents as needed Neither Ip nor HV LED is blinking both are dark Input drive power is too high The amplifier behaves as follows at various input drive power levels e When power is below 75 W the amplifier operates normally e When power spikes above 75 W a 500 ms timer starts during which time the power threshold is reduced from 75 to 65 W If you do not reduce the power to below the threshold at the end of 500 ms Fault 4 results e When power exceeds 100 W the absolute maximum value at which the amplifier can operate an immediate Fault 4 results Decrease the input drive power The amplifier shuts off and goes to State 0 A hard fault has occurred because input drive power exceeded 125 W causing plate current to exceed 2 5 A Ip gt 2 5 A Decrease the input drive power or retune the amplifier The amplifier shuts off and goes to State 0 A hard fault has occurred because significant plate current was detected when the amplifier was warming up or was unkeyed States 1 3 The threshold for this fault is one third of the value for a soft Ip trip or 533 mA 1 After the amplifier shuts off wait at least 20 seconds then use the ON OFF switch to turn the amplifier back on IMPORTANT When the amplifier trips out DO NOT repeatedly press the ON OFF switch to attempt to turn Page 7 3 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Diagnosing Faults and Troubleshooting the amplifier back on D
27. eration when connected to a 110 VAC outlet see Section 3 2 Limitations of Operation at Nonstandard Voltage page 3 4 Provide proper airflow Page 3 1 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Preparing Your Station Page 3 2 Step 3 Step 4 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 of clearance around the air intake and exhaust areas to allow for unobstructed airflow Ensure that exhausted air cannot recirculate back into the amplifier air intake We recommend that you do not stack equipment on top of the amplifier If you are mounting the amplifier in a console ensure that the exhaust air is properly and fully removed from the console If outlet air is drawn back into the amplifier air intake and recirculated the amplifier gets hotter and hotter resulting in degraded performance or even failure If you are designing your own console consider putting in additional fans and or ducting to deal with waste heat Minimize the possibility of dust or other contamination getting drawn into or falling on the amplifier Periodically at least annually clean the dust out of the amplifier paying particular attention to the tube fins We recommend the use of compressed air for dust removal Ready your antenna for 1500 W Ensure that
28. ey 4 3 4 4 Connect the Voltage Tap 4 3 4 5 Connect the Cables 4 4 4 6 Set the Input Drive Power 4 6 4 7 Connect the Transceiver Keying Line 4 7 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 Damage to other station equipment may also result Proceed slowly throughout these procedures to avoid bumping and damaging adjacent wires connectors and components 4 1 Unpack the Amplifier and Transformer DOCNUMBER 8410 Document Issue 1 0 March 2014 Step 1 Step 2 Step 3 Procedure 4 1 Unpack the amplifier and transformer Prepare your station as described in Chapter 3 Preparing Your Station Remove the amplifier and transformer from their cartons The Alpha 8410 ships in two heavy duty double wall cardboard boxes The carton containing the amplifier weighs 50 Ib 23 kg the carton containing the transformer weighs 43 Ib 20 kg 2a Inspect the boxes for shipping damage 2b Unpack the boxes and place the contents on a workbench or table 2c Retain the boxes and all packing material in case you need to ship the unit later Inspect the amplifier and transformer for shipping damage If you find damage call RF Concepts technical support Page 4 1 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Setting Up the Amplifier 4 2 Connect
29. f the tubes The Alpha 8410 linear amplifier specifications are as follows Table 2 2 Alpha 8410 linear amplifier specifications Parameter Frequency coverage Input drive level Power output SWR tolerance Duty cycle Tubes DOCNUMBER 8410 Document Issue 1 0 March 2014 Value 1 8 29 7 KHz 50 W nominal 1500 W 3 1 100 2x VTX X118 Alpha 4CX1000A Page 2 7 Alpha 8410 Linear Amplifier User Manual Amplifier Components and Specifications RF Concepts LLC Table 2 2 Alpha 8410 linear amplifier specifications Continued Parameter Intermodulation level Harmonics Mode of operation Input AC voltage AC current Input impedance Output impedance RF connectors Cooling Size Weight T R relay Tuning band switching Display Interface Protection RF bypass level Page 2 8 Value 30 dB minimum two exciter 50 dBc CW SSB FM 100 120 200 220 240 selectable lt 15 amps 240 VAC 1500 W 50 ohms 50 ohms SO 239 Forced air 17 3 W x 7 H x 21 0 D including fan space 70 lb 31 8 kg Vacuum QSK Manual Bar graph LED USB Against all common faults lt 500 W DOCNUMBER 8410 Document Issue 1 0 March 2014 3 Preparing Your Station 3 1 Prepare Your Station 3 1 3 2 Limitations of Operation at Nonstandard Voltage 3 4 3 1 Prepare Your Station Step 1 Step 2 DOCNUMBER 8410 Document Issue 1 0 March 2014 The Alpha 8410 is capable of dramatically improving the performance of yo
30. he WAIT LED goes out and the OPR or STBY lights stop blinking indicating that warmup is complete move the OPR STBY switch to OPR Step 7 Proceed to Section 5 3 Tune the Amplifier page 5 3 5 3 Tune the Amplifier DOCNUMBER 8410 Document Issue 1 0 March 2014 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 Your goal in tuning the amplifier is to maximize output power for a given input power Any linear amplifier must be adjusted for optimum efficiency and linearity at each specific power level Operation at higher or lower power results in the following Page 5 3 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Operating the Amplifier REMEMBER Page 5 4 e Operation at higher power without appropriate readjustment results in flat topping also known as splatter and usually excessive amplifier grid current e Operation at lower power results in decreased amplifier efficiency Recommended practice is to tune first into a dummy load or artificial antenna then connect the antenna and make any slight final adjustments that may be needed For any frequency where antenna VSWR is gt 1 5 1 it is important to carefully tune the amplifier for a proper match The Alpha 8410 does not contain an
31. he two boards 4c Connect the transformer s 6 pin yellow connector to the matching pins on the amplifier s HV board the lower of the two boards 4d Ensure that all connector pins on these three connectors engage fully and correctly Secure the transformer into place from the bottom of the amplifier by inserting the supplied bolts 1 4 20 12 inch hex bolts with 4 inch washers through the four clearance holes in the chassis and into the nuts in the transformer base DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC Alpha 8410 Linear Amplifier User Manual Setting Up the Amplifier 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 Procedure 4 3 Check the tubes and the exhaust chimney Step 1 Ensure that the tubes are firmly seated in their sockets The 4CX1000A tubes have bayonet style bases Each tube is installed onto a central pin in the tube socket and then rotated clockwise into place so that the flanges on the tube line up with the connectors in the socket To remove a tube rotate it counter clockwise and then pull it up out of the socket Step 2 Ensure that the anode connector is tightly clamped to the tube Step 3 Ensure that the silicon rubber exhaust chimney is straight and that the bottom is firm
32. he wrong position example Ip Set the switch to the correct position The transformer may be plugged into the power supply incorrectly Check the power supply wiring and connectors to ensure that the input and output connectors and the voltage taps are set properly An HV circuit fault may exist Check the line voltage The HV sampling resistor in the power supply may be damaged Contact RF Concepts technical support DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC Amplifier turns on but HV reading is low as indicated on the multimeter bargraph Amplifier turns on but time delay does not complete and WAIT LED does not turn off Amplifier turns on and time delay completes but amplifier does not transmit Amplifier operates properly then turns off completely Amplifier transmits but red GRID LED lights often When switching from STBY to OPR mode receive signals disappear or are severely attenuated DOCNUMBER 8410 Document Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual Diagnosing Faults and Troubleshooting The plate voltage to the power supply may be too low Check the line voltage and confirm that the tap is set correctly The timing circuitry on the control board may be damaged or defective Contact RF Concepts technical support The T R control line key line connection to the amplifier may be faulty 1 Confirm that the key line is inserted into the correct jack on
33. hm dummy load This capacitor should be adjusted only at the factory The board also has an 800 V protection device on the RF output Tube Deck Board The tube deck board is located in the tube deck below the tube sockets It contains critical circuit elements that need to be in close proximity to the tubes The tube heater bias and screen connections are all located on this board The tube deck temperature sensor and the input match for the tubes complete this board For more information on the tube deck see Section 2 4 Tubes and Tube Deck page 2 6 Page 2 5 Alpha 8410 Linear Amplifier User Manual RF Concepts 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 BAND Selects an amateur band designated in megahertz MHz LOAD Controls the load capacitor Sets the amplifier plate loading and determines the power level at which best efficiency and linearity are achieved In general loading is heavier at higher output power TUNE Controls the tune capacitor Sets the output tank circuit to resonance within each band Higher frequencies tend to tune toward the 0 end and lower frequencies toward the 100 end of the dial scale 2 3 Output Tank Circuit The output tank circuit provides reliable high efficiency low distortion performance in a very compact volume The basi
34. ifier 6 3 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 Do not apply oil or grease to any amplifier components There are no user accessible lubrication points in the amplifier The amplifier is equipped with a cover interlock switch that removes primary power from the amplifier and a crowbar that short circuits high voltage to the chassis when the cover is lifted These interlocks protect against electric shock resulting from accidental contact with the lethal voltages inside the amplifier The cover interlock is intended only as backup protection against accidents Never depend on it Always disconnect the power cord from the AC mains before removing the cover IMPORTANT Do not disable the interlock switch for any reason 6 1 Clean the Amplifier Chassis Perform this procedure at least once a year Procedure 6 1 Clean the amplifier chassis Step 1 Power down the amplifier Step 2 Clean the exterior with a mild liquid detergent Do not use chemical solvents as these may severely damage the front panel or cabinet finish Never use an abrasive cleaner DOCNUMBER 8410 Document Issue 1 0 March 2014 Page 6 1 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Maintaining the Amplifier
35. ithout a separate ground commonly found in the US 1b Connect the black and white power cord wires to the two hot wires of the AC source Either wire may be connected to either side of the line For best results use a dedicated 200 240 V branch circuit of 10 AWG copper wire or equivalent rated at 20 A to feed the amplifier Replace the amplifier cover and all attachment screws Use only the 6 32 screws supplied with the amplifier and do not tighten any of the screws until all are started WARNING Do not attempt to operate the amplifier with the cover removed or placed on the unit without the attachment screws Doing so damages the amplifier and may also cause injury or death to the operator Place the amplifier in its operating position on a stable surface with sufficient space to the rear sides and top to allow good air flow and safe placement of cables Connect the amplifier RF INPUT to the transceiver RF OUTPUT Use 50 ohm coaxial cable RG 58C U or equivalent Page 4 5 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Setting Up the Amplifier Step 5 Step 6 The amplifier s relay jack has 12 V onit 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 Connect the amplifier RF OUTPUT to the antenna Be certain to use coax cable that is rated for at least 1500 W Connect the transceiver T R con
36. letely Retune the amplifier Ensure that the amplifier is not overdriven E px 3 Fix any problems in the bias control circuitry 4 If the amplifier has shut off wait at least 20 seconds then use the ON OFF switch to turn the amplifier back on 5 If the amplifier trips again immediately investigate and resolve the problem before attempting to turn the amplifier on again DO NOT repeatedly hit the ON switch when the amplifier trips out Doing so is likely to result in severe damage to amplifier components When you are certain that you have taken care of the problem that caused the fault you may turn the amplifier back on HV LED 1s blinking Reflected power is too high The amplifier trips when reflected power exceeds 250 W At 1500 W output this represents a voltage standing wave ratio VSWR fault exceeding 3 1 DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC Resolution Fault type 4 LED behavior Cause Resolution Fault type 5 LED behavior Cause Resolution Fault type 6 LED behavior Cause Resolution DOCNUMBER 8410 Document Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual Diagnosing Faults and Troubleshooting 1 Check the output coaxial cable and connectors replace or reconnect 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 Make adjustm
37. ly against the tube deck and completely covers the airflow opening in the deck The chimney should be flush with the top cover when it is placed back on the amplifier Tube cooling exhaust must exit only through the tube anode fins it must not be allowed to escape outside them IMPORTANT Damage caused by insufficient cooling airflow is not covered under warranty 4 4 Connect the Voltage Tap Selecting the appropriate tap for your situation optimizes amplifier performance safety and lifetime IMPORTANT We strongly recommend that you operate the amplifier on 240 VAC If you choose to do otherwise see Section 3 2 Limitations of o Operation at Nonstandard Voltage page 3 4 The primary voltage taps are located on the top of the mains board between the transformer and the front panel There is a row of five fast on connectors J22 to J26 and a flying jumper connector that mates with them see Figure 4 1 DOCNUMBER 8410 Document Issue 1 0 March 2014 Page 4 3 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Setting Up the Amplifier J 240V 220V 200V ibe LN ax la 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 These five nominal primary voltages 100 120 200 220 and 240 V cover all the line voltages normally encountered around the world The nominal
38. mplifier bias is unexpectedly loading may be insufficient Decrease drive from the transceiver decreasing Recheck the amplifier tuning 2 The coaxial connector coax feed line antenna feed point balun tuner or antenna trap may be arcing on voice peaks Replace the faulty components 3 RF feedback may exist from the antenna into the transceiver via the transceiver power cord microphone or key cable or other unshielded station patch cables Ensure that all power cords microphone and key cables and other cables are properly shielded and grounded 4 The station RF ground may be poor Ensure that the amplifier and transceiver have a proper RF ground Required drive to maintain The tubes may be aging Contact RF Concepts technical support to 1500 W is steadily increasing determine whether the tubes need to be replaced DOCNUMBER 8410 Document Issue 1 0 Page 7 6 March 2014 Terminology Terminology NOTE For detailed explanations of the following terms see various publications including the latest American Radio Relay League ARRL Handbook A AB1 Modulation class AB1 Class that provides good linearity in a push pull configuration AC Alternating current Electric current whose magnitude and direction vary with time ALC Automatic Level Control Technology that automatically controls output power B B1 Modulation class AB1 Amplifier circuit class that provides good linearity in push pull c
39. n State 5 Page Term 2 RF Concepts LLC exciter Radio that provides RF drive for the amplifier to operate The transmitter portion of the transceiver FSK Frequency shift keying Type of frequency modulation in which information is conveyed by shifts in the output frequency between predetermined values HV High voltage Electrical circuit in which the voltage used presents risk of both electric shock and electrical arcing Hz Hertz One periodic event per second kV Kilovolt 1000 V kVA Kilovolt ampere 1000 W capability kVA 0 8 kilowatts kW Kilowatt 1000 W DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC L LED Light emitting diode Semiconductor diode that emits incoherent narrow spectrum light providing a form of electroluminescence mA Milliampere 10 A O OPR Operate P PSK Phase shift keying Digital modulation scheme in which information is conveyed by Q QSK Quadrature shift keying Digital modulation scheme in which the transmitter is on only for the duration of each dot or dash and R RCA Radio Corporation of America Also a type of interconnecting plug RF Radio frequency Frequency within the range 3 Hz 300 GHz RG x x Coaxial cable type DOCNUMBER 8410 Document Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual Terminology LV Low voltage Electrical circuit in which the
40. nal Certain faults cause the amplifier to return to this mode Operational but Key in has not been asserted unkeyed y To enter this state Wait for the amplifier to complete its 3 minute warmup then press the OPER switch In this state The amplifier is fully warmed up but the key in line has not been activated The exciter is still connected to the antenna Keyed no RF Key in has been asserted but no RF is sensed To enter this state Wait for the exciter to short the key in line to ground In this state The input and output relays are activated the tubes are biased on at a very low current the exciter is connected to the input of tubes and the antenna is connected to amplifier output Power Amplifier is keyed RF has been sensed and amplifier delivers power To enter this state Wait for the amplifier to sense RF In this state The tubes are biased to the operational condition The amplifier is now fully operational and delivering power to the load IMPORTANT To clear a fault o e For a gain fault wait for the amplifier to reset itself e For all other faults resolve as described in Chapter 7 Diagnosing Faults and Troubleshooting Then move the amplifiers OPR STBY switch to STBY and finally back to OPR to continue 5 2 Start Up the Amplifier Procedure 5 1 Start up the amplifier Step 1 Install and set up the amplifier as described in the preceding chapters Step 2 Power up the amplifier b
41. ng line Connect the transceiver keying line The following is a list of popular transceivers and considerations for their connection to the amplifier For advice on other transceivers contact RF Concepts as described in Chapter 1 Introduction Table 4 1 Popular transceivers Transceiver Connection and keying information Icom RF T R Connection with the Send jack For information see the transceiver user manual Kenwood RF T R For information on connecting to external amplifiers see the transceiver user manual Yaesu RF T R Connection with the RCA TX GND connector and or TX GND signal in the DIN Band Data connector For information see the transceiver user manual Older For information on connecting to external amplifiers transceivers see the transceiver user manual Page 4 7 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Setting Up the Amplifier DOCNUMBER 8410 Document Issue 1 0 Page 4 8 March 2014 5 Operating the Amplifier 5 1 Principles of Operation 5 1 5 2 Start Up the Amplifier 5 2 5 3 Tune the Amplifier 5 3 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 At that point it is ready for use The Alpha
42. o station go to www rfconcepts com and click Support Provide surge protection Induced energy from nearby electrical storms or other power transients may damage amplifier components Such damage is not covered under warranty It is therefore important to use a good lightning arrestor However the only lightning proof solution available is to disconnect antenna feedlines and AC power when the equipment is not in use NOTE Whenever the amplifier is online either off on standby STBY or warming up with the WAIT LED lighted the amplifier is bypassed and the exciter is connected directly to the antenna For SWR 1 1 the throughput limit in all cases is 500 W For a higher SWR the power level should be reduced accordingly Any power level higher than this may damage the RF switching relays in the amplifier Page 3 3 Alpha 8410 Linear Amplifier User Manual Preparing Your Station RF Concepts LLC 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 For expected behaviors at nonstandard line voltages see Table 3 1 Table 3 1 Amplifier behavior with nonstandard line voltages Line voltage Low 90 130 V High gt 250 V NOTE apply Expect
43. oing 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 3 Fix any problems in the bias control circuitry 4 When you are certain that you have taken care of the problem that caused the fault turn the amplifier back on 7 2 Troubleshoot Problems Amplifier does not turn on nothing happens when the ON switch is pushed Amplifier turns on but no HV is indicated by the multimeter LED bargraph Page 7 4 External AC wiring a fuse or a circuit breaker may be open Check and correct wiring replace fuse or reset circuit breaker The amplifier cover may not be in place or properly secured or the cover safety interlock may be open Ensure that the cover is in place and all screws are securely inserted One or more connectors may be loose Check that all of the transformer connectors are securely attached that the 3x3 molex connector at the back of the amplifier is fully engaged and that the two connectors between the transformer and the HV power supply boards are firmly inserted Fuse FI F3 may be open or missing Check fuses with an ohmmeter Replace any blown fuses with fuses of the same size The step start resistor may be open Check the resistor If it is damaged replace it The multimeter selector switch may be in t
44. onfiguration C CW Continuous wave Electromagnetic wave of constant amplitude and frequency D dB Decibel Logarithmic unit of measure of the power of sound relative to a reference level DOCNUMBER 8410 Document Issue 1 0 March 2014 ampere Unit of electric current ARRL American Radio Relay League US national organization of amateur radio operators For more information go to www arrl org AWG American wire gauge Standard method of denoting wire diameter Page Term 1 Alpha 8410 Linear Amplifier User Manual Page Terminology E EBS Electronic bias switching A form of switching that increases negative grid 1 voltage in pauses in speech or between Morse code elements resulting in reduced standing bias on the tubes F FCC Federal Communications Commission For more information go to www fcc gov FM Frequency modulation Modulation scheme in which information is conveyed over a carrier wave by variations in frequency H HF High frequency Radio frequency within the range 3 30 MHz Ip Idling plate current Plate current measured when the amplifier is keyed and RF is not present K key Signal from the radio to the amplifier that instructs the amplifier to switch from receive to transmit mode because the radio is ready to generate RF power The programmable delay between keydown and RF out is generally 8 12 ms When the amplifier is keyed it 1s i
45. only used modes and on any authorized amateur frequency from 1 8 to 29 7 MHz other than the 60 meter band e Compatibility with popular amateur transceivers and exciters The Alpha 8410 requires 50 W peak RF drive for 1 5 kW output e Capable of full CW break in QSK and all digital modes when used with any appropriate transceiver e Built in protective functions The control system incorporates protective functions that minimize the probability of accidental damage to the amplifier or its power tubes In most cases when one of the protective functions is tripped the amplifier goes to standby e USB interface allows for remote operations diagnostics and firmware upgrades 1 3 Safety Considerations e 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 DOCNUMBER 8410 Document Issue 1 0 Page 1 2 March 2014 RF Concepts LLC Alpha 8410 Linear Amplifier User Manual Introduction e When moving the Alpha 8410 use proper lifting techniques and two people Never transport the amplifier with the transformer in place e Although the Alpha 8410 meets international safety standards and FCC regulations remember that the equipment works with high voltages that can be LETHAL 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 o
46. perate the Alpha 8410 Failure to perform procedures properly may result in amplifier damage fire hazard or electric shock IMPORTANT e NEVER open the amplifier case without unplugging the unit from the wall outlet d e NEVER touch an antenna during transmission e NEVER turn on the amplifier without the cover securely in place and all attachment screws inserted e NEVER turn on the amplifier without a good ground connection on the rear panel ground terminal e NEVER turn the amplifier back on after a hard fault that is a fault to power off without waiting at least 20 seconds e NEVER cover or obscure the exhaust holes in the amplifier cover Never stick objects into the holes or allow liquids to enter through the holes e NEVER allow key down plate current to exceed 1 5 A for more than 1 or 2 seconds If you do and a plate current trip occurs it automatically resets in 4 seconds if the amplifier is returned to receive key up e NEVER allow the red GRID LED to stay brightly illuminated for more than 1 second 1 4 Related Products Other products available to enhance your use of the Alpha 8410 include e Alpha 2000 full 1500 W rated 50 ohm dummy loads e Alpha 4500 series standing wave ratio SWR meters and wattmeters For more information go to www rfconcepts com or call 303 473 9232 DOCNUMBER 8410 Document Issue 1 0 March 2014 Page 1 3 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Introduction
47. river chip It receives data from the controller via a serial peripheral interface SPI It contains a regulator to drop voltage from 12 V to 5 V for the display HV Board The main high voltage for the amplifier is created on the HV board using a full wave bridge rectifier and a bank of capacitors This power supply has two 10 ohm resistors one in the positive B lead and one in the negative return that goes to ground This combination of resistors limits the surge current in the case of a B arc The voltage across the resistor in the negative return is used to monitor tube plate current in the control board It is also used to generate a hard fault condition When the power supply current exceeds 2 5 A a relay opens the coil circuit of the mains tap relays on the mains board causing the amplifier to go to the power off state This hard fault circuit operates independently of microprocessor control The regulated screen supply is also located on this board All power supply filter capacitors on this board have bleeder resistors that discharge the capacitors in less than 60 seconds If you must work on this board confirm the discharged condition with a voltmeter due to the remote possibility of bleeder resistor failure DOCNUMBER 8410 Document Issue 1 0 Page 2 4 March 2014 RF Concepts LLC DOCNUMBER 8410 Document Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual Amplifier Components and Specifications Main
48. s 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 Relays on the mains board connect the AC line to the appropriate taps on the transformer primary Also on the mains board is a step start circuit This circuit consists of a relay and a resistor which are time sequenced to limit the inrush current into the amplifier when it is first turned on When the amplifier is initially turned on the tap relays operate from a voltage derived from resistors from the AC line They hold via contacts on the trip relay on the HV board The regulated 12 and 124 V supplies are also located on this board Many of the important voltages for the amplifier are brought to test points on this board The primary voltage taps are located on the top of the mains board between the transformer and the front panel There is a row of five fast on connectors J22 through J26 and a flying jumper connector that mates with them T R Board The transmit receive T R board contains the RF input and RF output relays as well as the input power detection and output directional wattmeter Voltages from the detector are connected to the control board A trimmer capacitor on this board has been adjusted at the factory with the amplifier operating into a good 50 o
49. the Transformer Page 4 2 NOTE i Step 1 Step 2 Step 3 Step 4 Step 5 e The transformer is very heavy When moving it use due caution and handle only by the lifting handle e Do not over tighten the screws that hold the transformer in place as doing so may cause excessive vibrations or noise e If you move the amplifier even if only from one site to another locally remove the transformer first to avoid the possibility of damage Procedure 4 2 Connect the transformer Remove the amplifier cover and set it aside Position the amplifier on a flat surface at or near where it is to be used with plenty of room for you to work The amplifier chassis is designed for the mechanical loads experienced when the amplifier is on a flat surface with the tilt bail up or down Installing the amplifier on a tilt so far that the transformer is cantilevered or hangs out to any degree can cause the chassis to distort Pick the transformer up by the handle and move it onto the lip at the edge of the chassis about half way into the amplifier Connect the transformer 4a Connect the transformer s 9 pin white Molex connector to the matching 3x3 Molex connector on the back of the amplifier s back wall Use the handle to move the transformer all the way into the amplifier and push it toward the center 4b Connect the transformer s 8 pin orange connector to the matching pins on the amplifier s mains board the upper of t
50. trol cable to the amplifier s KEY IN input The amplifier has a full break in vacuum relay QSK system that requires only the normal interconnection when used with a modern QSK transceiver The amplifier requires a contact closure short circuit on transmit on the amplifier s KEY IN jack center pin to the chassis This function is supplied by the transceiver usually from a dedicated relay that is normally open in receive and closed in transmit 6a Use shielded wire for the T R control cable Fit the amplifier end with a common phono RCA type plug and the transceiver end with a suitable connector 6b Ensure that the T R relay contact closes Protection circuitry prevents hot switching when RF drive is applied Modern transceivers have the proper time delay between key up and the start of the transmitted signal to allow the amplifier to follow the CW keying NOTE The Alpha 8410 s grid current limiting circuits provide substantial tube protection against possible damage The amplifier does not generate or use Automatic Level Control ALC voltages to control an exciter You need only set the input drive power as explained in Section 4 4 page 4 3 For proper operation set the exciter transceiver s power output so as not to overdrive the amplifier input If the transceiver is more than 15 years old reduce the power output so that voice peaks do not overdrive the transmitter under any modulation condition 4 6 Set the Input Drive Power
51. ummarized in Table 7 1 and described in the following text Table 7 1 Fault types LED behavior Fault type Cause IpLED IpLED we LED Blinking we Amplifier gain is below 10 dB Plate current in the tube exceeds 1 5 A Dark Blinking Blinking Reflected power 1s too high 4 Dark Input drive power is too high 5 Plate current exceeds 2 5 A 6 Plate current was detected during warmup Faults 5 and 6 do not display on the front panel Rather they indicate only through telemetry via the USB port W Page 7 1 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Diagnosing Faults and Troubleshooting Fault type 1 Fault type 2 Fault type 3 Page 7 2 LED behavior Cause Resolution LED behavior Cause Resolution LED behavior Cause Both Ip and HV LEDs are blinking Amplifier gain has fallen to lt 10 dB This is an important safety feature of the amplifier as many different problems can be detected as a drop in gain So that this fault does not occur while the amplifier is being tuned gain fault detection is disabled when drive power to the amplifier is below 20 W This allows correct initial amplifier tuning to be achieved before going to full power 1 Reduce the input drive power 2 Retune the amplifier Ip LED is blinking Plate current in the tube has exceeded 1 5 A If the current exceeds 2 5 A AC select relays are de energized and the amplifier shuts off comp
52. ur 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 This chapter provides a few important operational considerations We recommend that you also consult a good source of general information such as the latest Amateur Radio Relay League ARRL Handbook for Radio Amateurs especially if this is the first high power amplifier that you have used Procedure 3 1 Prepare your station Provide 240 VAC power The amplifier runs best when powered by a 200 240 VAC circuit If you do not have a 240 VAC outlet in your station have a licensed electrical contractor install one A minimum of a 20 A capacity is required A 20 A breaker on your 240 V circuit is sufficient Select a location for the outlet as close as possible to where you expect to operate the amplifier If you are not sure or contemplate moving the amplifier consider installing two outlets The amplifier is shipped with a NEMA 6 20 style plug installed Ask the contractor to measure the voltage and record it for reference If possible have the contractor measure the line voltage with a 10 A current draw and use this value for setting the transformer tap Although the amplifier can run when connected to a 120 VAC outlet you MAY NOT achieve full legal limit output in this case Rather you should not expect more than 1000 W output For more information on the limitations of op
53. w The amplifier includes a 5 V power supply mounted behind the front panel Whenever the amplifier is plugged into the mains power this supply is active and there is power to the microcontroller on the main control board This feature enables the amplifier to be turned on or off remotely It also enables remote monitoring and debugging via a USB cable connected to a computer 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 Page 2 1 Alpha 8410 Linear Amplifier User Manual RF Concepts LLC Amplifier Components and Specifications Page 2 2 Figure 2 1 Amplifier front Keep top tube Keep rear exhaust clear i intake clear Figure 2 2 Amplifier back Air inlet Key line input RF input RF output i I eee N I de i d RAGA LOZZO Chassis ground connector 2 AC fuses 1 step start fuse DOCNUMBER 8410 Document Issue 1 0 March 2014 RF Concepts LLC 2 1 Boards IMPORTANT DOCNUMBER 8410 Document Issue 1 0 March 2014 Alpha 8410 Linear Amplifier User Manual Amplifier Components and Specifications Figure 2 3 Amplifier interior Output tank circuit Tubes ee ii fe Output RF connector v F Cooling fan r Input RF connector HV safety switch AC transformer molex k a a i p ate ay pria ca 3 tg ILA L
54. y moving the OPR STBY switch to STBY standby Step 3 Rotate the multimeter selector switch to HV Step 4 Press the POWER ON switch DOCNUMBER 8410 Document Issue 1 0 Page 5 2 March 2014 RF Concepts LLC Alpha 8410 Linear Amplifier User Manual Operating the Amplifier The following occur e The fan and blower begin to operate If there is no air flow from the amplifier and no sound of blower operation immediately turn the amplifier off and investigate e Within 2 seconds the HV display moves all the way to the right certainly to more than 2500 V If it is lower than this investigate further the primary taps may not be correctly set e The red LED representing 1800 W output power lights up indicating the start of a built in 80 second countdown 1800 10 180 seconds As the timer counts down the remaining time is indicated by the currently lit LED on the power output bargraph Step 5 Move the multimeter selector switch to Ip plate current No current should be indicated during the entire warmup period The WAIT LED blinks about twice per second indicating that warmup is still in progress The FAULT OPER and STBY LEDs remain unlit Step 6 Ensure that exhaust air is detectable from the exit vent holes above the tubes If exhaust air is not detectable 6a TURN OFF the amplifier immediately 6b Ensure that the exhaust chimneys are properly positioned over the tubes 6c Power up the amplifier again 6d When t
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