ACOM 1010 user manual
Contents
1. 5 1 ACOMI0I0 Simplified Schematic Diagram The 4CX800A GU74B Svetlana high performance ceramic metal tetrode VI with plate dissipation of 800 W is grid driven The input signal from the RF INPUT jack is passed through a broadband input matching circuit which consists of components on the INPUT PCB and includes the drive power swamping resistor Rsw This circuit tunes out the input capacitance of the tube The swamping resistor Rsw is a termination load for the matching circuit and can dissipate up to 80 W of RF drive power It also eliminates any tendency toward oscillation by the tube ensuring excellent RF stability of the amplifier The cathode resistor Rc creates DC and RF negative feedback thus stabilizing gain and equalizing frequency response The combination Lp Rp in the plate circuit is a VHF UHF parasitic suppressor DC plate voltage is fed through chokes RFCI RFC2 and the capacitor Cb3 blocks it from the output The output tank comprised of LPI LP2 LL CPI CP3 and CLI CL4 forms a classic Pi L network and suppress harmonic frequency emissions This circuit is switched and tuned by SIA SIC and the air variable capacitors CP 1 2 and CLI 2 The output signal is fed through the antenna relays KI and K2 in the WATTMETER PCB The WATTMETER PCB also includes a high pass filter for frequencies below 100 kHz and it prevents the plate supply from reaching the antenna The plate RF voltage is monitored through the capacitor Ca and together2. least 20 W of forward power output is achieved In the event successful matching cannot be accomplished check the BAND switch position and antenna selection Then check the antenna VSWR at the same drive freguency d Tuning hint A benefit of TRI is that the knob positions are virtually independent The plate load resistance decreases to the right and increases to the left of the TRI center A centered tuning indication corresponds to the proper LOAD capacitor tuning which presents an optimum load resistance to the tube If the LOAD knob is turned to the left with a centered TRI there will be more gain but less linearity When available drive power is insufficient or when less output but better efficiency are needed e g for RTTY and SSTV this may be desirable Tuning to the right of the center would lead to the opposite result i e less gain and more power attainable Of course this reguires more drive power more plate current and more plate heat which shortens tube s expected life Off center tuning may also be used to compensate for line mains voltage variations in order to maintain tube efficiency In that case tune to the left when line mains voltage is high or tune to the right if it is low However where there is more than a 10 difference from the nominal line mains voltage the voltage selector inside the amplifier should be changed See Section 2 2 Line Voltage Selection 4 6 The Auto Protection System When any a
3. primary line mains fuses in the amplifier are located on the rear panel Fig 2 1 They are of the fast guick blow type European size 5 x 20 mm Use 10 A for 100 120 V ac operation 6 3 A for 200 240 V ac operation Suitable types are For 120 V 10 A 250 V 5 x 20 mm fast quick blow LITTELFUSE 0217010 Wickmann 1942100000 For 240 V 6 3 A 250 V 5 x 20 mm fast quick blow LITTELFUSE 021 706 3 Wickmann 1931630000 Besides the primary fuses there are also fuses located on the HV PCB and on the MAINS PCB inside the amplifier They are European size 5 x 20 mm 0 8 A 2 A and 5 A time lag slow blow type Suitable types are HV PCB 2 A 250 V SLOW BLOW Time Lag 5 x 20 mm LITTELFUSE 0218002 Wickmann 1951200000 MAINS PCB 5 A 250 V SLOW BLOW Time Lag 5 x 20 mm LITTELFUSE 0218005 Wickmann 1951500000 MAINS PCB 0 8 A 250 V SLOW BLOW Time Lag 5 x 20 mm BUSSMANN type S504 800mA These latter fuses must not be replaced by the user Replacing these internal fuses is potentially dangerous and must be done only by a trained service technician Contact your ACOM dealer for assistance 5 3 Tube Replacement A single Svetlana 4CX800A GU74B high performance ceramic metal tetrode is used in the amplifier Replacement is a complex and potentially dangerous operation that involves adjustment of the plate idling current This should not be attempted by the user Contact your ACOM dealer 5 4 Simplified Schematic Diagram See Fig
4. reflected power and real output to the antenna and transmission line of only 300 W In the event your antenna cannot be adjusted to produce a lower VSWR an external antenna tuner may be deployed CAUTION At elevated VSWR levels high voltages and high currents are distributed along the coaxial cable to the antenna risking internal arcing and heat generation and likely damage to the cable and any antenna switches that may be used It is recommended that VSWR levels of more than 3 1 not be permitted with coaxial cable above 14 MHz It is advisable to adjust amplifier tuning when antennas have been changed snow has fallen new objects are in the near field of the antenna etc Such changes may affect antenna impedance NOTE If you use more than one antenna on a band the proper antenna must be selected prior to performing the tuning procedure outlined below CAUTION To avoid damage not covered under warranty do not switch the BAND switch knob while transmitting As discussed above hot switching will damage the amplifier s band switch CAUTION Also never apply drive longer than one minute continuously without pausing for at least one minute to allow the tube to cool It is recommended that for initial tuning a frequency in the middle of the band be used First with no transceiver power applied select the band Then use Table 4 1 to achieve an approximate preset for both TUNE and LOAD capacitor knob settings LOAD Kno
5. with the RF WATTMETER is the main source of information for the control circuit of the amplifier in evaluating tuning quality The control circuit is based on the ATMEGA 8L micro controller from Atmel All voltages are delivered from the line MAINS and HV PCBs The currents of the control grid screen grid and the plate as well as the reflected power and tuning quality etc are continuously monitored by the micro controller Many 15 software derived protections are based on this information Detailed electrical schematic diagrams are available from ACOM or from your dealer on reguest 5 5 Service Functions By pressing the OPER and RTTY buttons simultaneously the upper LED bar graph is switched to the service mode which is indicated by both red bar graph lights and the yellow GI light illuminating Pressing the OPER and RTTY buttons together again will select additional service measurement functions Pressing them a final time will return the amplifier to the normal operating mode These steps are detailed below a Press the OPER and RTTY buttons together The two red lights on the right side of the upper bar graph will illuminate to confirm that the amplifier is in the service mode The yellow GI light will also illuminate The upper bar graph should show a grid current reading no higher than 5 mA 5 LEDs illuminated b Pressing the OPER and RTTY buttons once again will now illuminate the yellow G2 light This provides a
6. HF LINEAR AMPLIFIER O GD s wine WO ORS99S9 99990898 B IP miecse 3355 3 s gt wf 4 1 zeza LOAD TUNE so rejne Ah YN Aa NE bije 10 gt Z 100 HF LINEAR AMPLIFIER GO ACOM G2 when illuminated a screen grid overload condition exists reduce the drive power and or refresh the tuning Section 4 5 for safe operation IP when illuminated a plate current overload condition exists reduce the drive power and or refresh the tuning Section 4 5 for safe operation F when illuminated the amplifier automatic protection has tripped If F is accompanied with one of the GI G2 or IP condition indicators the cause of the protection trip will be evident When F alone is illuminated check the keying wiring Section 2 4 d See Section 4 6 for details about the auto protection system 4 OPERATION Operation of the amplifier is simplified through ACOM s innovative TRI tuning aid Auto Operate function and automatic protection systems To make full use of the amplifier s potential and to configure it to local conditions the following information should be read carefully 4 1 Turning ON and OFF In order to turn on the amplifier press the power switch ON at the bottom right corner of the front panel The LED indicator above the switch will glow green and the audible cooling fan will start Following aseries of automatic self tests the OPER LED will begin to flash gr
7. b Dial TUNE Knob Dial 1 800 2 000 3 500 4 000 7 000 7 300 10 100 10 150 14 000 14 350 18 068 18 168 21 000 21 450 24 890 24 990 28 000 29 700 Table 4 1 Approximate tuning preset b Tuning Procedure 1 Once the antenna and band have been selected and the TUNE and LOAD adjustments have been initially set as indicated in Table 4 1 apply between 10 and 20 W of continuous key down CW signal 2 Look at the upper LED bar graph FORWARD POWER and adjust the TUNE right hand capacitor for maximum indication 12 3 Watch the TRI indicator above the LOAD left hand capacitor and turn the LOAD capacitor in the indicated direction to center the green LED indicator light 4 Increase the drive power to get the desired nominal output then repeat steps 2 and 3 always peaking output with the TUNE adjustment NOTE No light on the TRI indicator means that the tuning is too far off To correct this turn the LOAD and TUNE knobs around the table suggested positions until the TRI indicator illuminates no light tuning is far left tuning is far right marker inside LOAD is tuned use TUNE knob turn LOAD knob turn LOAD knob turn LOAD knob turn TUNE knob for max Power to the right to get to the left to get slightly left to peak Forward to get any marker the inside markers inside markers to center it Power Fig 4 1 Using TRI tuning aid The TRI indicator will not illuminate until at
8. bnormal amplifier condition is detected by the auto protection microprocessor the risk will be evaluated automatically and either of two levels of protection will be applied a The first degree of protection consists of an illuminated LED warning These include the yellow LED warnings discussed earlier i e GI grid 1 G2 grid 2 and IP plate Operation may be continued but the amplifier is likely to proceed to the second degree of protection the trip b The second degree of protection is a trip to the standby mode The red F fault LED illuminates and the amplifier automatically goes to the standby mode for several seconds Also the green OPER LED goes off The amplifier will indicate the reason for the protection trip 13 if one of the yellow GI G2 IP warning LEDs is illuminated along with the F LED a current limit has been exceeded drive power must be reduced or retuning is necessary if the last red LED of the reflected power bar graph is illuminated together with the F LED the reflected power limit has been exceeded the drive must be reduced or the antenna VSWR must be improved if all three LEDs of the TRI are flashing simultaneously together with the F LED the tuning is not adjusted correctly most likely the antenna impedance has changed and retuning is required Fault information normally remains on the display for several seconds while the amplifier is in the standby
9. e STBY mode such as when you leave the station for a while The green LED goes off and the Auto Operate function is suppressed temporarily Pressing the OPER button again restores the Auto Operate feature 4 3 RTTY Mode Select the RTTY mode to operate continuous duty modes such as RTTY SSTV or other data modes The LED indicator above the RTTY button illuminates and the amplifier operating parameters are changed to reduce tube dissipation In the RTTY mode the amplifier output power is reduced to a maximum of 500 W There is no need to adjust tuning when changing between RTTY and normal modes CAUTION To avoid damage not covered under warranty do not change modes during transmission That is do not change to or from RTTY or any other mode when transmitting 4 4 Antenna change By pressing the Al A2 button the amplifier output is switched between the two corresponding antenna outputs ANTI and ANT2 The lights above the button indicate the current antenna selection CAUTION To avoid damage not covered under warranty do not change the antenna during transmission 4 5 Tuning Tuning is possible only in the OPER mode a Preliminary information Tuning the amplifier involves a procedure of matching the impedance of the antenna and transmission line to the amplifier tube s characteristic load resistance This will ensure maximum plate efficiency and RF gain at nominal output power with minimal distortion and spurious output No
10. een and will continue to do so during the 150 second warm up period Throughout this period the amplifier will remain in the standby mode and the transceiver may continue to be used Also during this period the Al A2 button may be pressed to change antennas i e between the antennas connected to the ANTI and ANT2 terminals on the rear panel of the amplifier Switching between the antennas does not affect the warm up process CAUTION To avoid damage not covered under warranty do not change the antenna output during a transmission i e never press the Al A2 button when transmitting NOTE When you intend to have a short operating break it is better to place the amplifier in the standby mode rather than turning it off Tube life is shortened by repeatedly turning it on and off After the warm up period is complete the OPER LED stops flashing and remains illuminated green 4 2 Changing Operate and Standby Modes The OPER button changes between two modes When the green light above the button is illuminated the amplifier will remain ready to operate even automatically returning from standby after a high drive protection trip That is after a protection trip e g from an overdrive event the amplifier will normally shift to the STBY mode for several seconds but it will automatically return to the OPER mode after that This is the Auto Operate feature Alternatively the OPER button may be depressed manually to go to and remain in th
11. mode The auto operate function will attempt to return the amplifier to the operate mode automatically If the protection trips repeatedly the user must attend to the cause of the trip which is typically too much drive or antenna mismatch CAUTION If all LEDs in the bar graph area are flashing simultaneously you must immediately switch off the amplifier to avoid damage 5 MAINTENANCE If no indicator glows upon switching the amplifier on the main fuse s may have blown See Section 5 2 5 1 Cleaning WARNING Do not use solvents for cleaning as they may be dangerous to you and damage amplifier surfaces and plastic components Do not open the amplifier Cleaning the amplifier outer surface may be safely accomplished by using a piece of soft cotton cloth lightly moistened with clean water 5 2 Fuse Replacement WARNING If your amplifier is only fitted with one line mains fuse it is suitable for the European Community ONLY Your dealer will check that your amplifier is correctly fused before it is shipped to you based upon your indicated location Customers should check with a qualified electrician if the amplifier is to be used outside the country in which it was purchased CAUTION For 120 V ac operation the fuses should be rated at 10 A for 240 V ac operation the fuses should be rated at 6 3 A If it is necessary to replace the line mains fuses use only those that are permitted under local safety codes The two
12. n approximate reading of grid 2 voltage The upper bar graph should show a voltage reading within the range of either 270 300 Volts 9 10 LEDs illuminated for RTTY or 210 330 Volts 7 to LEDs illuminated for SSB and CW c Pressing the OPER and RTTY buttons yet again will illuminate the yellow IP light This provides an approximate reading of combined plate current and grid 2 current The reading should be no higher than 500 mA 10 LEDs illuminated for RTTY or 600 mA 12 LEDs illuminated for SSB and CW d Pressing the OPER and RTTY buttons a final time will restore the upper bar graph to its normal function of indicating peak forward power NOTE The auto protection system will continue to operate in the service mode 6 SPECIFICATIONS 6 1 Parameters a Frequency Coverage All amateur bands in the 8 29 7MHz frequency range extensions and or changes on request b Power Output 700 W PEP or 500 W continuous carrier c Intermodulation Distortion Better than 35 dB below rated output d Hum and noise Better than 40 dB below rated output e Harmonic Output Suppression Better than 50 dB below rated output f Input and Output Impedance Nominal value 50 Ohm unbalanced UHF SO 239 type connectors Input circuit broadband VSWR less than 3 1 1 8 30 MHz continuously no tuning no switching
13. te that REFLECTED POWER readings depend on the antenna and transmission line impedances only and not on amplifier tuning Ifthe load impedance is not a nominally resistive 50 Ohms the REFLECTED POWER reading will always show a reading no matter what the tuning settings Proper tuning is always necessary however and will allow you to operate at a high power level without distortion or any danger to the amplifier Note also that the real OUTPUT POWER presented to the load the antenna and transmission line is equal to the difference between the FORWARD and REFLECTED power readings For instance with a 2 5 1 VSWR readings of 800 W and 150 W FORWARD POWER and REFLECTED POWER respectively the real OUTPUT POWER is 650 W At very high VSWR levels such as when no antenna is connected or a badly mismatched antenna is used the FORWARD and REFLECTED readings will be almost equal while the real OUTPUT POWER the difference between them will be nearly zero The amplifier can operate safely as long as the REFLECTED POWER is LESS THAN 250 W Matching is assured for loads presenting a VSWR of up to 3 1 Nevertheless for some loads and bands matching is possible at even higher VSWR levels but the drive power must be reduced to prevent the REFLECTED POWER from exceeding 250W Failure to comply with these guidelines will cause the protection circuits to trip For example if the antenna VSWR were 5 1 the maximum attainable forward power would be 540 W 240 W of
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