AMERITRON AL-1200 FULL POWER LINEAR AMPLIFIER
Contents
1. 2W 1 103 2223 C1 27 pf Silver Mica 208 5404 D1 D4 1N34 or 1N 118 Diode 300 0346 C2 C7 150 pf Silver Mica 208 5396 R1 47K ohm 2W 5 101 0402 FILTER CAPACITOR BOARD 50 01167 1 C3 C4 01 uf Disc Ceramic 200 0416 R2 R3 180 ohm EW 5 101 0384 C5 C6 10 pf Disc Ceramic 200 3531 AL 1200 SCHEMATIC Power supply shown wired for 240V operation Si SHOWN IN le POSIT HH sano cen Lo oe A9 2000 208 5608 1500 208 5382 yat 10 13152 180 208 5605 500 208 5691 iist 10 13190 470 208 5440 20 08 606 e j PARTS LIST a Bi Blower 410 3737 1 3 01 uf SOV disc 200 0416 CA 27 pi silver mica 208 5404 C5 6 See input chart C7 10 01 uf 1RN disc 200 2121 Ci1 13 170 pf doorknob 209 0559 C14 18 500 pt doorknob 209 0412 cig 190 pf 4 5KV plate tuning 204 2570 c20 B00 pf 1 2KV loading 204 2573 1 C21 001 uf 7 5KV disc 200 2122 C22 23 01 uf 1 4KVDC disc 606 1185 Di iN4005 diode 300 0266 DL 1 4 12V wire lead meter lamp 420 0164 Fi 2 154 250V fuse 755 1431 F3 AA 250V fuse 755 1638 50 01140 1 Meter board assembly 50 011141 1 HV rectifier board assembly 50 01142 POVALC detector board assembly 50 017167 1 HY Filter cap board assembly Li See input chart a L2 High frequency coil 10 13147 L3 Low frequency coll e 10 airdux 404 0600 L4 Leon 12 airdux 404 0601 Mi Multimeter 1 mA 300 ohm 400 2602 M2 Grid meter 1 mA 300 ohm 400 2603 PCi 2 Parasitic choke amp plate cap assembly 10 10757 103 2180 Hi 33 ohm2. ALC negative going 0 20V adjustable phono jack Efficiency CW 65 typical Efficiency SSB envelope crest 62 typical MARS WARC yes bandswitch set to nearest amateur band Keying requires relay closure or sinking to ground of positive 12 VDC at 100 mA phono jack RF Connectors S0239 Line Connector NEMA 6 15P 240V style Dimensions 18 7 D x 17 W x 10 H Weight 77 Ibs Frequency Coverage 1 8 through 21 MHz amateur bands Third Order IMD at Rated Output 34 dB at 1500 w output specifications are subject to change without notice or obligation GENERAL INFORMATION SAFETY INTERLOCK While the Amplifier s top cover is in place the interlock switch closes to allow AC line voltage to reach the power transformer When the top cover is removed the interlock opens and disconnects the line voltage This does not discharge the bank of power supply filter capacitors Be sure to allow the filter capacitors to discharge before you touch anything inside the Amplifier You can select the High Voltage function of the Multimeter to check the high voltage potential Never attempt to defeat the safety interlock WARNING Never remove the cover of this amplifier with the unit plugged into the power line DRIVING POWER This Amplifier is designed to operate at full ratings when it is driven by an exciter that has approximately 100 watts of RF output You can use an exciter that has lower output power but the Amplifier s outpu
3. aw resistor 100 0403 R2 100K ohm pw resistor 105 1341 R3 10 ohm 12W resistor 103 9701 BECH Filament choke 10 15115 RFCS Plate choke 10 1573 RFC4 2 5 mH choke 402 1162 ALY 4 3 POT 104 123V DC relay 408 6139 ALY2 SPDT 120V AC relay 406 4700 ALY3 2 PST 30A 12V DC relay 408 2588 SI 6KV 20A bandswitch 500 3557 52 4 Rocker switch 503 1147 55 Interlock switch 504 3247 Ti HY plate transformer 406 1418 1D T2 7 5V filamentcontral transformer 406 1419 2J T3 Neutralizing transformer 10 14194 Wi 3JCX1200A7 tube 350 0590 701 2 7 5V 10W zener diode 301 8597
4. excessive The LOAD setting should be increased if grid current is excessive Any errors in adjusting this control should be made in favor of a higher load setting clockwise MULTIMETER GRID METER PLATE CURRENT 300 MA MPERE YS MULTIMETER Ip P O nu m e Su H i OPR AMERITRON AL 1200 AMPLIFIER PWR ge une ON MODE SWITCH STANDBY SWITCH SWITCH CW PROCEDURE Follow these instructions in numerical order If the various meter readings are different than indicated check the con nections from the exciter to the amplifier and make sure they are correct Consult the manual for the exciter Be sure the transformer is correctly installed and wired for your line voltage See the Transformer Installation section on page 4 and 5 for wiring details 1 Set the AL 1200 front panel switches as follows POWER TO OFF OPR STBY TO STBY SSB CW TO OWT RATT MTA AMON N Plug the AC line cord into the proper voltage outlet 3 Set the Power Switch to the ON position The meter lamps should light and the blower should start Read the 4000 volt scale on the Multimeter It should indicate 3600 volts nominal and no more than 3700 volts 4 With the amplifier still on STANDBY tune the exciter into a normal 50 ohm load according to the manufacturer s instructions Turn the exciter drive fully down after tuning 5 Place the amplifier mode switch in the CW position the bandswitch on the same band as the excite
5. load adjustments LOAD This control adjusts the coupling of amplifier to the antenna or load It should be adjusted to keep the grid current in the proper operating range As the loading capacitance is reduced by rotating the control to a higher front panel number the coupling is increased An increase in coupling will reduce grid current and increase the amount of drive the amplifier will accept without component damage A common mistake in tuning is to adjust the LOAD control at low drive powers and apply more drive dur ing operation Excessive grid current distortion on SSB or arcing in the tank components occurs when full drive power is applied to the amplifier without the LOAD set for enough clockwise higher loading It is important to remember the loading must be set properly for the PEAK power the amplifier is expected to develop 50 watts PEP will be the maximum drive the amplifier will safely handle if the output of the amplifier is tuned with 50 watts of carrier drive Any attempt to go beyond the amount of drive power the amplifier was originally tuned at will result in a rapid increase in grid current splatter and even damage to components The LOAD control should be adjusted for maximum output power without exceeding the recommended grid current DO NOT USE THE LOAD CONTROL TO REDUCE POWER IN A GROUNDED GRID AMPLIFIER The drive from the exciter should be reduced if the amplifier plate current or output power is
6. of voice and observe the reading on the 2000 RF Watts scale 6 Adjust the ALC ADJ control on the rear panel until the amplifier output is no more than the desired maximum power obtained in step 1 The exciter internal ALC will maintain linearity The amplifier ALC will prevent over power operation SSB PROCEDURE Tune the Exciter and Amplifier as described in TUNE UP CW 1 Place the SSB CW switch in the SSB position 2 Adjust the exciter gain control to permit voice peaks to reach the same value the peak output meter read on CW when fully loaded The plate and grid currents should remain well below 50 of the CW values during normal modulation NOTE Some exciters will put out short duration high power RF pulses when first keyed Exciter power output peaks may reach or exceed full output level even if the exciter s power control has been adjusted to deliver reduced power under keydown conditions The amplifier loading control must be set high enough clockwise to prevent extremely high energy levels from developing in the plate and grid circuits of the amplifier DO NOT UNDERLOAD THE AMPLIFIER TO REDUCE POWER Never retune the amplifier to produce higher ef ficiency with reduced drive Poor linearity splatter or even damage to components may result from failure to follow these The AL 1200 will operate with full output on all WARC bands except 24 5 MHz The AL 1200X export model will operate with full output
7. or radiators Be sure air can circulate freely around and through the Amplifier cabinet Provide an unobstructed air inlet for the blower Do NOT place anything that will impede the free flow of air within 2 inches of the cabinet ventilation holes VENTILATION The AL 1200 ventilation system has been designed and tested to maintain tube seal temperature safely below the tube manufacturer s rating at 1500 watts output with a 100 duty cycle when properly tuned The blower in the AL 1200 is a permanently lubricated type that requires no main tainence in normal operation To insure proper ventilation in your installation observe the following 1 Do not block or unduly restrict the ventilation holes in the cover Be sure that the amplifier is located in an area so the vent holes have open air circulation 2 The exhaust air flow is over 30 CFM Do not assist the air flow unless the fan exceeds the AL 1200 blower CFM by a factor of 2 1 3 Do not mount additional fans on the AL 1200 cabinet 4 The exhaust air will become quite warm at higher power levels Do not place any heat sensitive objects in the exhaust air stream POWER CONNECTIONS The AL 1200 is supplied with a NEMA 6 15P plug for 240V AC operation Operation with power main voltages below 200 volt is not recommended Special transformers are re quired for 200V 50 60 Hz operation Refer to the Transformer Installation section on pages 4 and 5 for the correct wiring for
8. the transformer will be mounted This package contains the chimney for the 3CX1200A7 There is also a small package that contains the fuses fuse caps and the remainder of the chassis screws Please read the GENERAL INFORMATION and SPECIFICATIONS sections before attempting to install the transformer and tube Go to the INSTALLATION section on page 4 to begin installing the transformer and tube 5 This amplifier must always be disconnected from the power mains before removing the cover See the precaution on page 10 Please read the entire manual to become familiar with the operation of the AL 1200 X amplifier FEATURES 1 Inexpensive tubes the AL 1200 uses a single rugged 3CX1200A7 tube 2 Fast warm up time the 3CX1200A7 requires only a few seconds of warm up time 3 SSB CW switch the bias voltage is switched to provide the best linearity on SSB or the lowest dissipation on CW operation 4 ALC Indicator the drive level is detected to provide a control voltage for the exciter ALC prevents over driving of the linear and reduces distortion from ex cessive drive power 5 Vernier Plate and Load Adjustments both tuning con trols have vernier 6 1 reduction drives for smooth tuning TECHNICAL SPECIFICATIONS AL 1200 Input Circuit type Pi network slug tuned coils maximum VSWR at resonance 1 2 1 minimum 2 1 VSWR bandwidth 20 maximum drive power permissible 130 watts typical drive for full power output 100
9. the left front side of the cabinet near the filter capacitors Most hardware stores stock suitable materials that are used as replacement filters for window air conditioners METERING The AL 1200 has two illuminated meters The Grid Current meter provides a continuous indication of the 3CX1200A7 grid current This exclusive feature of Ameritron amplifiers indicates proper amplifier operation better than any other parameter Do not exceed 300 mA on this meter during normal operation of this amplifier The other meter reads Plate Voltage HV Plate Current IP Peak RF Watts PO and ALC These functions are selected with the Multimeter Switch Plate Voltage HV Read DC Plate Voltage on the 4000 volt scale This scale is 100 volts per division Normal voltages are 3 00 volts no load 3300 volts full load Peak RF Watts PO Read Peak RF Watts on the 2000 watt scale This scale has 50 watt divisions below 1000 watts and 100 watt divisions above 1000 watts NOTE This circuit uses an emitter follower to charge a capacitor to the peak envelope voltage detected by the ALC Power Board Accurate peak envelope power readings are given when the amplifier is connected to a 50 ohm nonreactive load If the amplifier is used with a mismatched load the power meter will read higher or lower than normal by a ratio up to the value of the SWR Potentiometer R5 on the Meter Board 50 01140 1 adjusts the calibration of the power meter ALC Indicate
10. 220 to 240 volt operation NEVER REWIRE THE POWER SUPPLY TO BOOST THE HIGH VOLTAGE ABOVE 3700 VOLTS The wiring between the fuse box and the amplifier AC outlet must be No 12 gauge or larger in order to supply the current required 13 amperes without a significant drop in the line voltage The outlet should be fused for 20 amperes Connect a good RF and earth or water pipe ground to the ground post on the rear panel of the Amplifier Use the heaviest and shortest connection possible Before you use a water pipe ground inspect the connections around the water meter and make sure that no plastic or rub ber hose connections are used These connections interrupt electrical continuity to the water supply line Install a jumper around any insulating water connections you may find Use heavy copper wire and pipe clamps It is best to ground all equipment to one point at the operating position and then ground this point as described above TUNING INSTRUCTIONS Proper tuning of a grounded grid linear amplifier is best accomplished with an understanding of what each control does and what the meters are telling the operator about the canditian af TIT INF The tuning controls function as follows PLATE This control tunes the amplifier output circuit to the operating frequency It should always be adjusted for maximum output power or maximum grid current Due to interaction with the LOAD control a touch up should be performed after any
11. AMERITRON AL 2200 FULL POWER LINEAR AMPLIFIER INSTRUCTION MANUAL The Ameritron AL 1200 is a 1500 watt output linear amplifier that operates from 160 through 15 meters The Ameritron AL 1200X is the export model and covers 160 through 10 meters The AL 1200 uses a single 3CX1200A7 tube in a class AB2 grounded grid circuit CW FM and RTTY efficiency is improved by shifting the bias deeper into class B The heavy duty power supply and RF components combined with a forced air system utilizing chimneys provide long service life for expensive components The AL 1200 is shipped factory wired for 240 volt 50 60 Hz power mains PLEASE READ THIS MANUAL BEFORE OPERATING THIS EQUIPMENT AMERiITRUN 116 Willow Rd Starkville MS 39759 Koch UNPACKING INSTRUCTIONS Carefully remove the amplifier transformer and tube from their shipping cartons Inspect each item for visible damage If any damage occurred during shipment notify the transportation company immediately Save all packing materials in case you need to return your AL 1200 X for factory service The cartons have been designed to give maximum protection for this amplifier Any units returned without proper packing may be damaged and shipping claims cannot be made Contact the factory before returning any units Remove the screws that hold the cover to the amplifier Slide the cover back and remove it from the amplifier Remove the package that is in the area where
12. CROWBAR A 100 ohm 10 watt resistor may be clipped from ground to the HV Caution This page is only valid for transformers that contain these exact color codes for the primary winding Early production units did not contain a multiple tap transformer If the terminal strip has all these color coded wires then the unit has the multiple tap transformer FILAMENT BLOWER WIRING INSTRUCTIONS The AL 1200 amplifier comes prewired for 240V line voltage and with the blower prewired for medium high fan speed This page gives filament transformer connection details for various line voltages and blower speeds The five lug terminal strip and the single lug terminal strip are located immediately behind the ON OFF rocker switch inside the unit The drawing below shows the connection of transformer leads and their purpose XFMR LEAD BLACK 1 BLK WHT 2 ORANGE 4 BROWN 5 WHITE 6 PRM V AC REFERENCE 220 V 240 V 120 V This chart shows the color code of the transformer leads and their purpose The number in paren thesis indicates the number of the terminal lug that the transformer lead is connected to The number three 3 lug is not used to change the filament or blower wiring Do not add or remove any wires from the number three 3 lug Refer to the drawing above Use the lug numbers above when referr ing to both of the Filament connection chart and the Blower connection chart below FILAMENT TRANSFORMER LINE VOLTAGE BLOWER There ar
13. e following information is required to assist you with operational problems 1 Model and Serial Number 2 Date of purchase and dealer 3 An accurate description of the problem Meter readings at all stages of the tuning proceedure are very important along with a complete description of the other equipment used with our product Written assistance is also avaiable Due to time delays in processing mail please allow at least three weeks for a writ Ben AMERITRON 116 Willow Road Starkville MS 39759 Tel 662 323 8211 Fax 662 323 6551 PERIODIC MAINTENANCE The high voltage present on the plate choke and air variable capacitors attracts dust and dirt out of the air stream It is particularly important that the high voltage areas at the bottom of the plate choke and the insulators on the air variable capacitors be dust free These areas should be inspected every few months if the amplifier is operated in a dusty environment Unplug the line cord and wait about 90 seconds until the power supply capacitors discharge Remove the cover and connect a jumper wire from ground to the anode connection of the tubes NOTE This is a safety wire that must be installed when beginning service work and removed when work is finished Use a soft bristle brush dipped in alcohol to clean areas men tioned previously In the event that cleaning is required at frequent intervals place a low restriction air filter material over the air inlet holes on
14. e two wires that connect to the terminal lugs The GREEN and WHITE wires from the rear of the unit which determine the Filament Line Voltage The BLACK connect to the terminal lugs to control the air speed of the wire from the power switch and WHITE wire from rearof fan The AL 1200 is prewired for the medium high speed the unit connect to different terminal lugs depending on the setting Refer to the chart below The blower connections voltage desired The AL 1200 comes prewired for 240V can be moved to lower speed taps if air noise is excessive operation Refer to the chart below The voltage listed in Ameritron recommends using the highest speed tap that the chart below is the maximum line voltage that should be hoise considerations permit The lowest speed tap will applied to a given tap Operation with line voltage in excess develop sufficient air flow for standard amateur SSB and of the tap voltage selected can result in a reduction of tube CW full power operation The highest speed taps should be life used for contest or RTTY operation LINE VOLTAGE BLOWER SPEED LUGS 245 V 232 V 220 V 208 V Do not add or remove any wires Do not add or remove any wires Gel L IL enee a Josee TT wareware S NU eo foo fenown fT T e feren oreen oreen oreen indicates Factory shipped indicates Factory shipped INTERCONNECTION 1 Connect the RF output of the exciter to the RF IN connector 100mA o
15. f current when pulled to ground on the rear of the AL 1200 with 50 ohm coax Use any good quality 50 ohm cable long enough to connect the amplifier 4 Connect a short ground lead from a good earth and RF ground to the exciter The amplifier uses a standard SO 239 female to the GND terminal that will mate to a PL 259 male connector on the cable 5 The 12V connection on the rear panel provides 12V DC at 100 mA maximum to operate external dial lamps or 2 Connect the existing station antenna system to the RF OUT accessories such as the ATR 15 Antenna Tuner connector on the rear of the AL 1200 with RG 8 type coax This connection uses PL 259 connectors 6 DO NOT CONNECT THE ALC OUT SOCKET ON THE AMPLIFIER TO THE ALC SOCKET ON THE 3 Use shielded audio type cable with standard male phono TRANSMITTER UNTIL INSTRUCTED TO DO SO IN plugs to connect to the RELAY jack on the AL 1200 This THE TUNE UP PROCEDURE This jack provides up to 20 jack has positive 12V DC open circuit and supplies Volts of negative voltaqe for transmitter gain control TO ANTEMALA oi ar i da St OWT AAL GG KOREA GE Grp I i i e TN D HOT INSTALL THIS CABLE UNTIL INSTRUCTED Ta mp 59 IN TUNE UP PROCEDURE e j ke DEER A C POWER PLUG F Ou Abo ral IER Ok TRABICEIVER TO EARTH Te b INSTALLATION Cont LOCATION Do not operate the Amplifier in excessively warm locations or near heating vents
16. on all WARC bands STANDARD FREQUENCY COVERAGE AL 1200 160 meters 1 8 2 0 MHz 80 meters 3 3 4 4 MHz 40 meters 6 3 8 3 MHz 20 meters 9 5 15 5 MHz 15 meters 15 5 21 5 MHz AL 1200X 160 meters 1 8 2 0 MHz 80 meters 3 3 4 4 MHz 40 meters 6 3 8 3 MHz 20 meters 9 5 15 5 MHz 15 meters 15 5 21 5 MHz 10 meters 24 29 MHz WARNI NG MAKE NO ATTEMPT TO PUT THIS AMPLIFIER IN SERVICE WITH THE COVER REMOVED CONTACT WITH VOLTAGES INSIDE THIS AMPLIFIER CAN BE FATAL ALWAYS DISCONNECT THE AMPLIFIER FROM THE POWER MAINS AND WAIT FOR THE FILTER CAPACITORS TO DISCHARGE BEFORE REMOVING THE COVER ALL CAPACITORS 01 uF 1KV DISC ALL DIODES 1N5408 1000V 3AMP lot RLY PO 200 2121 300 0145 Q Q METER BOARD el 50 01140 1 861 0545 e al C3 R8 O RECTIFIER BOARD HVM 12V AUX 12V AC 50 01141 1 861 0459 1 5 AMP 50V bridge 300 9646 R1 R2 6 ohm 3W 1 103 3399 01 uf 50V disc 200 0416 R3 R4 1 5 ohm 3W 1 103 3400 1000 uf 25V 203 0149 R5 100K ohm trimpot 104 0534 10 uf 25V 203 0642 R6 33K ohm W 5 101 0644 2N3904 305 0645 R7 15K ohm 2W 5 101 0273 R8 10K ohm 12W 5 101 0643 R9 10 ohm 12W film type 101 0595 01 uF SOV 8 ELECTROLYTIC CAPACITORS 200 0416 210 uF 450V 303 0578 1 uF 50V 200 0754 8 RESISTORS 50K OHMS 7W 5 103 7580 RFC 10 15168 ALC POWER BOARD 1N5408 300 0145 50 01142 861 0574 47K OHMS AW 5 4 RESISTORS 1M OHMS 101 0402
17. or maximum output power Repeat this step twice The output should be over 1000 watts now 11 Apply enough drive to indicate either 1500 watts of output power or 300 MA of grid current Re peak the LOAD and PLATE controls The final grid current should be around 250 mA and the plate current below 900 mA ALC Automatic Level Control The primary use of the ALC is to reduce the input drive power to a safe level for the AL 1200 The maximum drive of the AL 1200 will tolerate is approximately 130 watts At this drive level the output of the AL 1200 may be in excess of 2000 watts when properly tuned The ALC should be connected and adjusted after the amplifier is properly tuned on CW Use a shielded audio type cable with a standard male phono connector to connect the 0 20 volt negative ALC voltage to the exciter ALC input Consult the exciter manual for proper connection details Setting the ALC ADJ Control Proper adjustment of the rear panel ALC control can be achieved by the following steps 1 Load the amplifier according to the tune up instructions with the ALC disconnected from the exciter to the desired maximum power 2 Connect the ALC line and rotate the ALC control fully clockwise looking at the rear of the unit 3 Set the MULTIMETER switch to the PO position or observe an external PEP meter or oscilloscope 4 Set the transmitter audio control about 20 higher than normal 5 Speak in the microphone in a normal tone
18. or the blower is shown in the Transformer Connections instructions PLATE SUPPLY The plate supply has a full wave bridge rectifier and a 1 8 KVA CCS rated tape wound hypersil transformer Filtering is accomplished by a bank of high quality capacitors totaling 26 mfd additional capacitance will not improve supply performance The Plate Supply will not be harmed by normal continuous amateur operation at 1500 watt levels Power is applied through RLY2 when the 12V DC low voltage supply is activated A 10 ohm resistor limits the line current during the filter capacitor charge time to lower the stress on components When the primary voltage approaches the full line value RLY3 shorts the 10 ohm resistor and applies the full line voltage to the plate transformer The 10 ohm resistor acts as a fuse during start up if the high voltage supply has a short EXPORT MODIFICATIONS A simple modification will allow operation on frequencies above 15 meters Instructions for this modification are available by sending a written request for Export Modification Instructions along with a copy of a valid amateur license There is no charge for this information Export models are shipped with this modification and have an X following the serial number Standard frequency coverages are indicated in the chart following the tuning instructions on page 6 TECHNICAL ASSISTANCE Technical assistance is available during our normal business hours on weekdays Th
19. r the PLATE control in the dial range for the band selected and the load control as indicated CW PHONE 556 Frequency Load Frequency Lost 1 810 2 1 850 3M 3 600 3 3 900 6 7 050 a 7 200 4 14 050 4 4 14 250 5 21 050 5 21 350 6 28 050 T 26 500 D LOAD A 4 A athe want 3 W I D OPERATION 6 With exciter drive still at zero place the MULTIMETER switch in the Ip position Observe the 1000 mA scale The meter should read zero 0 Place the STBYOPR switch in the OPR position 7 Key the exciter no drive and observe the plate current on the 1000 mA scale It should be 40 mA Place the CW SSB switch in the SSB position Plate current should now read 150 mA Return the CW SSB switch to the CW position Note The no drive currents will vary up to 25 due to component and line voltage tolerences 8 Apply only enough drive to indicate a grid current of 100 mA or an Ip of no more than 500mA Tune the PLATE control for maximum output power or grid current It is normal for the plate current to dip at this point If the grid current goes over 150 mA reduce the drive at once Unkey the exciter 9 Place the MULTIMETER switch in the PO position and observe the 2000 Peak RF Watts scale Increase the drive until 200 mA of grid current is indicated Adjust the LOAD and PLATE controls for maximum output The grid current may be lower now 10 Advance the drive to 250 mA of grid current Adjust the LOAD and PLATE controls f
20. s a relative drive level average not PEP that can be estimated by dividing the Peak RF Watts scale by 10 NOTE There is a neutralization tab mounted on a ceramic standoff near the 3CX1200A7 This tab increases the amplifier s efficiency on 21 and 28 MHz DO NOT CHANGE THE POSITION OF THIS TAB NSTALLATI ON TRANSFORMER INSTALLATION Remove the cover of the amplifier Remove the package that is in the plate transformer area This is the fuse pack and chimney for the AL 1200 Remove the top 7 16 nuts from the four transformer mounting bolts inside of the amplifier Carefully remove the transformer from its shipping carton Place the transformer on the four 4 20 mounting bolts Use care because the transformer is heavy The side with the two high voltage secondary RED leads must be adjacent to the center panel see Fig 1 Now place a 7 16 nut on each bolt see Fig 2 Snug the nuts down manually Do not tighten with a ratchet wrench Remove the brass 4 hex nuts and the top flat washer from the two brass 6 32 screws on the rectifier board see Fig 1 Install the RED lead ring terminals on the screws and replace the flat washers and 1 4 hex nuts Position the wires so that the black insulated areas are at least Ju from each other and any metal objects Now tighten the 4 hex nuts For 240V Operation factory wired The four primary leads have colored plastic insulating boots over the quick disconnect terminals Slide the
21. se back prior to installing the leads Install the color coded boots as follows see Fig 1 BLUE Brown wire to the top relay terminal YELLOW Black White to the top terminal of terminal block CLEAR Black wire to the second terminal of terminal block RED Brn Wht 240V Grn 220V to the bottom terminal of terminal block Now slide the colored insulating boots back over the terminals Important The leads must be in the positions indicated by the color coded insulating boots see Fig 1 for 240V operation For 220V operation see page 5 Caution Do not use the 220V wiring unless the line voltage is always below 220 VAC The Standard USA voltage is 240 VAC not 220 Center Panel Blue Cap aa Brown wire RK llow C Gi Yellow Cap L Bik Wht wire a Clear Cap Black wire Red Cap Brw Wht wire TRANSFORMER INSTALLATION Cont For 220V connections see Fig 3 follow these steps 1 Slide the RED boot back ON the BRN WHT 2 Clip the terminal connector off the wire and slide the RED hoot off 3 Remove the restraint from the GRN wire and slide the RED boot on to the wire 4 Solder the terminal connector to the GRN wire 5 Tape up the BRN WHT wire because it will not he used Fig 3 Center Panel Red Cap Green Wire TUBE INSTALLATION Note that one of the tube pins is offset This offset pin keys the tube base and socket Install the tube by aligning the tube pins with the socket con
22. t will be less If you use an exciter that delivers more than 100 watts carefully adjust the driving power to avoid over drive and the creation of spurious signals which create needless interference to other operators We highly recommend that you use a monitor scope for continuous output monitoring The display on an oscilloscope is the best way of determining the amplitude of the voice peaks which if excessive can cause flat topping and splatter IMPORTANT In no case should you advance the power output control of your exciter beyond the point where the Amplifier s Power Output indication ceases to increase If you turn the control past this point nonlinear operation may occur FILAMENT SUPPLY The filament circuit of this amplifier satisfies all requirements of the tube manufacturer related to tube performance and life Inrush current is controlled by the transformer internal resistance and impedance filament choke resistance and filament wiring resistance To insure maximum life of the tube never replace any circuit components or wiring with substitute parts The low voltage tap on the filament transformer primary pro vides the ability to operate the blower at slower speeds for reduced noise Normal amateur operation in CW and SSB will not cause heat damage to components on any recommended tap It is always advisable to use the maximum speed air flow that the level of noise permits to extend component life Wiring information f
23. tact terminals then seat the tube with vertical pressure ONLY Do not rack ar turict the tuhe Place the chimney over the tube anode with the large opening down DO NOT FORCE the chimney down over the anode Carefully lower the chimney with an even pressure until it seats outside the four metal retaining clips on the socket TUBE INSTALLATION Cont After the chimney is installed attach the anode connector as follows Refer to the Fig 4 1 Remove screw A that holds the anode con nector to the 500pf blocking capacitors 2 Attach the anode connector to the tube Anode Position it so screw A can be re installed 3 Snug down nut B just enough to prevent the anode connector from sliding 4 Insert screw A into the 500pf capacitors and snug it down Fig 4 ANODE CONNECTOR Top View of 1200 Tube Recent production model AL 1200 amplifiers have a neutralization tab located next to the 3CX 1200A7 This change results in additional efficiency on 21 and 28 MHz This tab should not be altered in position In the event the tab becomes displaced proper neutralization will occur when the maximum output power and grid current and minimum plate current appear concurrently This adjustment is obtained by changing the tab to tube spacing BE SURE TO REMOVE AC POWER FROM THE AMPLIFIER AND ALLOW BLEEDERS TO DISCHARGE POWER BEFORE REMOVING THE COVER NEVER DISCHARGE AMPLIFIER HV TO THE CHASSIS WITH A SCREWDRIVER OR A
24. watts Output circuit type Pi L Pi in hour continuous carrier 1500 watts Below 18MHz 30 second continuous carrier 1800 watts plus in hour PEP two tone test 1800 watts Power Supply circuit type full wave bridge capacitor input no load voltage 3600V full load voltage 3300V full load current 8 amp regulation 10 or better transformer 32 Ibs hypersil capacitors 26 mfd total computer grade maximum draw at rated output 13 amps at 240V AC 50 60 Hz Tube type 1 3CX1200A7 continuous dissipation 1200 watts warm up time 10 seconds 6 Two Illuminated Panel Meters the AL 1200 has two il luminated panel meters The Grid Current meter pro vides a continuous reading of grid current and indicates proper operation of the amplifier The other meter reads Plate Voltage HV Plate Current IP Peak RF Watts PO and ALC 7 Operate Standby Switch filament and plate voltages are maintained while allowing the amplifier to be bypassed for barefoot operation 8 12 Volt Auxiliary Jack 12 volts at 100 mA is provided for accessories such as the ATR 15 Antenna tuner 9 XMT Indicator LED provides a front panel indication of proper amplifier keying by the exciter during operation Caution This amplifier must be disconnected from the power mains before removing the cover See the warning on page 10 Metering multimeter plate current plate voltage drive ALC power output PEP watts Grid grid current
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