. HF POWER LINEAR AMPLIFIER INSTRUCTION MANUAL The Ameritron AL-811H is an economical 800 watt PEP output linear amplifier that operates reliably from 160 through15 meters. The AL- 811H uses four 811A tubes in a class AB2 grounded grid circuit. Heavy duty power supply and RF components provide long service for components.
NOTE: Fuses supplied are for 120/110/100V operation (Models AL-811H/HY). If you are rewiring the AL-811H for 240/230/220V operation, you must use 8 ampere fuses. The AL-811HX export model is pre-wired for 240V operation and is supplied with 8 ampere fuses. The AL-811H is a grounded grid linear amplifier developed by Frequency Coverage Ameritron using low cost 811A power triodes. It operates in Domestic model (AL-811H): 160, 80, 40, 30, 20, 17 and 15 class AB2 for SSB and CW. The interlock switch stays closed to allow AC line voltage to ALC line disconnected.
The ALC line can then be connected reach the power transformer as long as the AL-811H's top cover and the ALC control on the amplifier can be adjusted to a point is in place. The exhaust air flow is over 20 CFM. Do not 'assist' the appropriate setting indicated by the chart below. Note: the AL- air flow unless the fan exceeds the AL-811H fan CFM by a 811H transformer allows operation on 100V line voltage in factor of 2:1. Connect the RF output of the transmitter or transceiver to Connect the shortest possible ground lead from a good earth the RF IN connector on the rear of the AL-811H with 50 ground to the GND terminal. The best leads are solid ohm coax. It should be 75mA.
Instructions on page 4 for wiring details. NOTE: The no drive current will vary up to 25% due to Set the AL-811H front panel switches as follows: component and line voltage tolerances. During POWER/OFF-ON to OFF tune up, limit Key to 7 seconds. Ameritron offers a high Ameritron for details on the QSK-5. The AL-811H will operate with full output on all WARC bands except 24.5 MHz The AL-811HX/HY will operate with full output on all WARC bands STANDARD FREQUENCY COVERAGE.
PERIODIC MAINTENANCE The high voltage present on the plate choke and air variable Remove the cover and connect a jumper wire from ground to the capacitors attract dust and dirt out of the air stream. It is anode connection of the tubes. Particularly important that the high voltage areas at the bottom NOTE: This is a safety wire that must be installed when of the of the plate choke and the insulator on the air variable. AL-811H SCHEMATIC Power supply shown wired for 120V operation. AL-811H INPUT CHART BAND C3 (pF) C4 (pF) 28.75T (405-1287) 1300 (250-1130E) 100 (250-0100) 23.75T (405-1237) 500 (250-0500) 750 (250-0750) 13.75T (405-1137) 500 (250-0500) 120 (250-0120) 20/30 330 (250-0330) 9.75T (405-1097) 270 (250-0270) 15/17 120 (250-0120) 6.75T (405-1067) 150 (250-0150). PARTS LIST (ctd.) Designation Description Ameritron Part # 2N3904 TRANS 305-3904 MJF3055 TRANS 305-3055J 4.7k Ohm, 1/2 Watt 101-3470 R2, 3, 4, 5 50k Ohm, 7 Watt, Type 170S 107-4500 R6, 7 1 Meg Ohm, 3 Watt 104-6100 1.5 Ohm, 3Watt, Type 135 104-0150 0.6 Ohm, 3 Watt, Type 135.
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I have a Ameritron AL-811 that has been converted to use 572B tubes. When I got it it would only do 100 watts so I replaced the tubes, let it sit on stand by for a day and then it would do 800 watts for a while. But after a little while it would start dropping off on power so I let it sit on stand by for several days and everytime I checked it it would be doing less power and now it only does about 80 watts. So does it make sense that it could go through tubes just sitting on stand? And why would it do that?
Could it be that the power supply voltage is too high? I think the voltage sits around 1800 volts according to the meter, but I'd have to check to make sure. The 572b tubes are a very durable transmitting tube.
You have to be very mean to them to make them go south. 1800 volts is probably the minimum you would want to run them at, they run better at around 2500. Check your idling current on the plates. To do this key the amplifier with no carrier or RF input.
You should see around 90 milliamps of current. Then check the current at full output. You should see about 500 milliamps, which is a reference which you should not exceed. Watch the high voltage at full out and make sure it is not dropping to low, 300-400 volts drop is about right depending on how stout the transformer is. These are all things to look for if your amp is working normally.
Maybe some else will jump in with some other pointers too. 73 Ed KC0PZE. With 1800 volts and 500mA plate current those 572B's should show no color on the plates whatsoever under keydown conditions.In standby mode they should last a lifetime.As Ed said,check the bias.If it is too high the tubes will draw too much current but should still not be damaged.I would be suspicious of something in the power supply causing a drop in plate voltage but it must be awfully low to cause only 60-80 watts output.How many watts are you driving it with and is it being tuned and loaded properly?
Okay, I checked it out last night and here are my results, everything was done into a dummy load with a bird 43, with 10 watts carrier in on am I got 40 watts out, plate current-75ma grid current-30ma. Voltage without a carrier is 1800 and voltage with 10 watts in, 40 out was down to 1700.
Increasing the drive to 25 watts got 60 watts out but the grid current won't go over 80ma and the plate current won't go over 35ma. I tried it on various bands from 10-160 meters with the same results or at least close to. This is about the same way it acted before with the old tubes, then when I replaced them everything worked the way it should for a while.
Does this sound like the bias is off and needs adjustment? Thanks for all the help. Ameritron 811A The bias is established by the diodes D19 thru D24 in the B-minus lead (center-tap of the filament transformer). Check the diodes; they should all be the same.
Looking at the schematic, point W6 (B-minus) is connected to W5 when the relay RLY-1B closes. B-minus continues up thru S-4 (this switch could be flakey), thru the current meter, M1. R-10 is a 330 ohm resistor in series with the negative side of the meter (make sure it’s good) and, finally you have a 0.6 ohm resistor R-9 between B-minus and chassis ground. I am not sure how the conversion to 572B’s were done; are there any resistors on the tube sockets themselves (maybe 47 ohms at 2 watts?), if so check value of all and make sure that they all are connected. I cannot believe that the amplifier is eating tube with 1800 volts and no color showing; something is stopping you from drawing current.
Replace the DC Blocking capacitor, C-13. That amp should not require any mods to convert to 572B's.572B's are like 811A's on steroids.Electrically the same but with 160 watts plate dissapation instead of the 65 watts for an 811A. I'm confused by a couple of your statments: First you said: Okay, I checked it out last night and here are my results, everything was done into a dummy load with a bird 43, with 10 watts carrier in on am I got 40 watts out, plate current-75ma grid current-30ma.
Then you said: increasing the drive to 25 watts got 60 watts out but the grid current won't go over 80ma and the plate current won't go over 35ma. Are you sure that is right because more power output should result in more plate current,not less.Either way something is wrong with the bias because the plate meter should read around 110mA +/- 25% (according to the manual) with the amp switched inline and with no drive applied. Try reducing the loading control somewhat and see if that raises the grid current.It may be loaded too heavily. Check R12 and R13 in the ALC circuit as well as the setting of R14 which is the ALC adjust pot.If it is set wrong it will limit the amount of drive from the radio regardless of what the radio is set at.That is of course if you have the ALC line connected to your driver radio. After that:?::?. Uh, you're not running this from a 120-Volt 15-Amp outlet, are you? With adequate filament voltage on that tube, a 572B should last more or less forever in that box.
It's like running a box meant for the 572B on 'low' side all the time. If you're running it on 120 Volts, and the outlet circuit isn't stout enough, you'll see the color of the filaments inside, dim noticeably with full drive. This would indicate that the line voltage was falling under load, causing the 6.3 Volts on the filaments to fall, as well. This dimming of the yellow-white filament color indicates that the filament temperature is falling. Running that filament at too low a temperature can and will cause the tube to go 'soft', and appear to be worn out and weak. If this is in fact the root of the trouble, you won't see those filaments dim when you key it now. If you remember seeing that happen when they were 'fresh', that would be a clue.
And if you're running it from a stout 240-Volt circuit, this is probably not the cause. Click to expand.I'm glad we have a handle on the situation however, I have a problem with this conversion; there are circuit differences in the amps constructed to run 572B's and the amps constructed to run 811's 572B amps All the 572B amps have a grid leak resistor in the control grid circuit to provide 'self bias' for the tube. 811A Amps The 811 circuit has the control grid grounded; if a 572B tube is put in that circuit without the proper modifications done for the grid leak resistors then that tube (the 572B) IS gonna draw more current than it should and it's gonna draw current when it should n't. When the RF sensing keyer was put in there I wonder what was done to the center point of the filament circuit; I wonder if it is still switched thru a relay or is it hard grounded. I wonder why it was only doing 100 watts when it was sold to him?.
I predict that the damage has been done to that set of tubes. Just changing the line voltage will NOT undo the damage. Might have prevented it, had you done so in the first place.
You can run 120 Volts, so long as you hold the drive down to about half-throttle. If you draw less current from the wall, the voltage drop won't be that bad. A 20-Amp 120-Volt circuit will be wired with #12 wire. A 15-Amp circuit with #14, usually. The fatter wire will have a smaller voltage drop at the same current draw. The reason the problem is worse on a 120-Volt circuit is that you need TWICE the amperage on a 120-Volt circuit as you need on the 240.
This causes twice the voltage drop in the same size wire, for the same output wattage on the linear. Turn the drive down, and the current demand drops with it. So does the voltage drop on the outlet wiring. If the 811A tubes haven't had this same (mis)treatment yet, try them on a 240-Volt circuit, if you can. Or hold back to about half of full power. Either strategy will work. The old textbooks describe a procedure to 'rejuvenate' the thoriated-tungsten cathode in a tube like that.
I have had pretty poor results on the ones I have tried to bring back to life. Mostly it involves turning up the filament voltage on a test rig. More often than not, the filament just burns out. You DO have to blow air on them when trying this trick. The heat from the filament alone gets out of hand when you turn up the filament voltage, even for 15 or 20 minutes. If you placed larger wires in the wall, and fed your 120-Volt outlet with #8 or #6 wire, the problem would be partly fixed. Trouble is, most building codes forbid using wire larger than #12 for a 120-Volt circuit.
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Might void your homeowner's insurance if they discovered it after a house fire. Besides, wire that large won't fit under the screws on a 120-Volt outlet. Here's hoping the 811A tubes haven't been 'flattened' yet.
. AL-80B Instruction Manual WARNING!!!
NEVER APPLY POWER TO THIS AMPLIFIER WITH THE COVER REMOVED! CONTACT WITH THE VOLTAGES INSIDE THIS AMPLIFIER CAN BE FATAL!
PLEASE READ THIS MANUAL BEFORE ATTEMPTING TO OPERATE EQUIPMENT! Improper or abusive operation of this amplifier can damage the tubes or other components in this amplifier. Save the screws to re-secure the cover. Carefully lift the rear of the cover while sliding the cover back. The AL-80B is shipped with the fuses and fuse caps packed inside the amplifier. Additional screws will be included in the fuse pack if they are required. AL-80B Instruction Manual Ameritron AL-80B 1000 watt PEP Linear Amplifier Instruction Manual Features.1 AL-80B Technical Specifications.2 Introduction.3 Safety Interlock.
3 Circuit Descriptions.4 ALC.4 Dynamic Bias.4 Power Supply.5 Filament Supply. Tuned Input Board (50-0080-2).26 AL-80B Tuned Input Chart. 26 Meter Board (50-0080-3).26 Timer / Overload Board (50-0080-5).27 Al-80B Main Chassis Parts List.28 Frequency Coverage.29 Amplifier Tuning Log. 29 Notes.30. A multi-voltage heavy-duty transformer with a unique 'buck-boost' winding allows adjustment of the primary voltage to 14 different voltages centered on 115 and 230 Vac.
Microsoft works 4 5 oem ford. This versatile Ameritron feature allows the user to select the optimum primary voltage for maximum performance and life. AL-80B Instruction Manual AL-80B Technical Specifications Input: Circuit type: Pi-network, slug tuned coils Maximum VSWR at resonance: 1.3:1 or less Minimum 2:1 VSWR bandwidth: 20% of center frequency Maximum drive power permissible: 100 watts PEP Typical drive for full power output. AL-80B Instruction Manual Introduction The Ameritron AL-80B is an 800 watt CW, 1000 watt PEP output linear amplifier that operates on all Amateur bands from 160 through 15 meters. The AL-80BX and AL-80BY are export models that operate from 160 through 10 meters.
Export modification instructions are available with proof of a valid amateur radio license. The AL-80B contains an exclusive bias circuit that reduces the idling (quiescent) current very close to the tube's cut-off region.
The power amplifier tube in the AL-80B has a full resting period of very low dissipation between dots and dashes on CW and between words on SSB. The lower idling current reduces component temperature on both CW and SSB. AL-80B Instruction Manual Power Supply Filament Supply The filament circuit of this amplifier satisfies all requirements of the tube manufacturer related to tube performance and life. The filament voltage and inrush current are controlled by the power transformer's internal resistance and impedance, filament choke resistance, filament wiring resistance, and the step-start circuit. AL-80B Instruction Manual Multimeter The multimeter is the meter on the right. It continuously reads the forward peak envelope power on its left-hand scale (FWD). This scale is calibrated in 100 watt steps up to 2 kW.
The right-hand scale of this meter provides four metering functions that are selected by the 'MULTIMETER'. AL-80B Instruction Manual Wattmeter Circuit The AL-80B wattmeter circuit uses an accurate directional coupler followed by a true peak detector circuit. This circuit will accurately determine the true peak envelope power (PEP) of normal voice waveforms. If the load SWR is high, the true power reading will be obtained by subtracting the reflected power from the forward power. These conditions can be avoided by following the tuning procedures in this manual. In the AL-80B, a grid current of 250 mA (at 100 watts of drive) produces the rated grid dissipation of 20 watts. For maximum tube life, the grid current and drive power should always be kept below these values.
If this problem occurs frequently, the tube should be tested or replaced. The use of low quality tubes, tubes that have been stored for extended periods, or abused tubes increase likelihood of a 'gas arc'.
Ameritron recommends using only current code date Eimac 3-500Z tubes. Power Connections The AL-80B is supplied with a NEMA 5-15P plug for 120 Vac operation.
Full duty cycle operation with ac supply voltages below 100 volts is not recommended. The 'Transformer Connections' section on page 12 shows the correct wiring for various supply voltages. AL-80B Instruction Manual If the power mains have excessive resistance, the high voltage may sag to less than 2700 volts under load. Voltage sag will not hurt the amplifier if the fully loaded high voltage remains above 2500 volts.
Ameritron Al 80b 10 Meter Mods
CAUTION: Never allow the high voltage to exceed 3200 volts under any condition. The high voltage secondary of the AL-80B has three leads. The normal wiring is indicated on the circuit board silk-screen by the initials R/Y (RED/YELLOW) and R/G (RED/GREEN). For low power operation the R/Y and R/G wire can be reversed. AL-80B Instruction Manual Interconnections Connect the exciter's RF output to the 'RF IN' connector on the rear of the AL-80B with 50 ohm coax.
Use any good quality 50 ohm cable long enough to connect the amplifier to the exciter. This amplifier connection uses a standard SO-239 female that mates with a PL-259 male connector on the cable.
Delta Force Magnum 10 Meter Mods
ALC Metering, Controls, and Adjustments ALC Metering Functions The 'MULTIMETER' switch in the AL-80B has two positions that indicate the functioning of the ALC circuit. These positions are as follows: In this position the multimeter measures the output voltage of the ALC detector.
The full scale reading of the ALC detector is 35 volts. AL-80B Instruction Manual ALC SET In this position the multimeter measures the approximate grid current that will produce ALC activity. One zero must be added to the reading on the ALC/ HV scale for this function. For example: If the meter reads 15, add one zero (150). In this example ALC action will begin at approximately 150 mA of grid current.
AL-80B Instruction Manual During CW operation, the 'ALC SET' control voltage should be adjusted just high enough (clockwise) to allow the desired output power to be reached. The 'ALC SET' control should never be adjusted to the point where the grid current can exceed 200 mA under any tuning or drive adjustment condition. A second method of determining linear operation is to monitor the peak RF output power carefully on the AL-80B's internal meter. Determine the maximum obtainable RF output power and reduce the exciters power until there is a noticeable margin from the maximum output power.
This will insure some reserve power is available for random voice peaks. AL-80B Instruction Manual Tube and Component Life These guidelines will help prolong tube and component life, and minimize splatter. On SSB or other linear modes, virtually any amount of power will cause splatter if the loading is too light ('LOAD' control too far counter-clockwise). Always tune for maximum output with maximum drive power. (clockwise) to prevent excessive voltage and arcing in the tank circuit or excessive grid current. Repeated tripping of the grid overload circuit or intermittent arcing probably indicates the 'LOAD' control is adjusted too low. Set the AL-80B front panel switches as follows: POWER OPR-STBY.
AL-80B Instruction Manual With the exciter's drive level still on zero, observe the 750 mA Ip scale on the left hand meter. It should indicate zero (0) amperes. Place the 'STBY-OPR' switch in the 'OPR' position. Place the exciter in the transmit mode with no RF output. AL-80B Instruction Manual 11a. Increase the 'ALC SET' voltage (if the ALC is connected) until 180 mA (18 volts) is indicated.
Apply full drive (not to exceed 100 watts) and adjust the 'LOAD' and 'PLATE' controls for maximum RF output power. The grid current should not be allowed to go above 200 mA at this stage. Braiding or woven wire has a very high RF resistance and should be avoided. See the 'Grounding' section on page 11 of this manual.
More detailed suggestions on grounding are available by requesting Ameritron's Tech Bulletin on RF Feedback. QSK-5 unit. The QSK-5 operates directly from 120 Vac power lines. Ameritron also offers an internal QSK board as a space-saver for the AL-80B. This internal board is slightly less expensive. However, it provides less flexibility and serviceability than the external QSK-5 unit. NEVER make any unauthorized component or circuit modifications to this product.
The only acceptable source for modifications is Ameritron or a source approved by Ameritron. Unauthorized modifications almost certainly will increase the risk of equipment failure or personal injury. AL-80B Instruction Manual Parts List Power Supply / SWR Board (50-0080-1) Designator Description Ameritron PN D101,102,114,115 1N34A 300-0346 D103 1N757A Zener 9.1V 305-0757 D116-120 1N4001 300-0266 D104-113 1N5408 300-0145 C101 27 pF 500 V 208-5404 C102,105.001 uF 1 kV. Ameritron PN C201 (tube side) See input chart C202 (transmitter side) See input chart L201 See input chart S201 Input switch AL-80B Tuned Input Chart BAND C201 (pF) tube L201 C 201 (pF) transmitter side 2700 (208-5689) 28.75T (405-1287) 2000. AL-80B Instruction Manual Timer / Overload Board (50-0080-5) Designator Description Ameritron PN C501-506.01 uF 50 V disc 200-0416 C507,508.47 uF tantalum 203-0530 C509 100 uF 25 V 203-0564 D501, 502 1N4001 300-0266 D503 5.6 V zener 301-710 IC501. AL-80B Instruction Manual Al-80B Main Chassis Parts List Designation Description Ameritron PN Blower 410-3138 C1-3.001 uF 7.5 kV 200-7224 500 pF Doorknob 7.5 kV 210-0470 C5, 6 170 pF Doorknob 7.5 kV 209-0559 Air Variable Plate 204-2112 Air Variable Load.
AL-80B Instruction Manual Frequency Coverage AL-80B AL-80BX 160 meters 1.8-2.0 MHz 160 meters 1.8-2.0 MHz 80 meters 3.3-4.4 MHz 80 meters 3.3-4.4 MHz 40 meters 6.3-8.3 MHz 40 meters 6.3-8.3 MHz 20 meters 10.1-15.5 MHz 20 meters 10.1-15.5 MHz 15 meters 16.5-21.5 MHz. AL-80B Instruction Manual Notes.