AMERITRON AL-80A User manual

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AMERITRON AL-80A I
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LINEAR AMPLIFIER
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INSTRUCTIONMANUAL
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The Ameritron AL-80A Linear Amplifier is designed for over 1000 Watts
output SSB PEP (850 Watts output on CW) with high efficiency and total
reliability. The AL-80A covers the amateur radio bands 160 through 15
meters. It also features wide frequency coverage for MARS and other
services authorized to operate at high power.
.The AL-80A uses an Eimac 3-500Z high-mu triode in a class AB2 ground-
ed grid circuit.
A built-in ALC circuit prevents the amplifier output from flat-topping if
the exciter gain is inadvertantly set too high.
./ The AL-80A is factory wired for 117V, 50/60 Hz primary line voltage.
~A~!5liTII8~~
DIVISION OF
PRIME INSTRUMENTS,INC.
9805 Walford Avenue 8 Cleveland, Ohio 44102
Printed in U.S.A. / (-1035
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/~LATION
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TheAL-80Aventilationsystem has been designed and tested
to maintain tube seal temperatures safely below the tube
manufacturer's ratingwhen operated withinour guidelines.
To insure proper ventilationinyour installation,observe the
following:
1. Do not block or restrict the ventilation holes in the
cover.
2. The exhaust airflowis over 50 CFM.Donot "assist" the
air flowunless the fan used exceeds the AL-80Ablower
CFM by a factor of 2:1.
3. Do not mount additional fans on the AL-80Acabinet.
4. The exhaust air willbecome quite warm at high
power levels. Do not place any heat sensitive objects
in the exhaust air stream.
POWER CONNECTIONS
The AL-80Aissupplied with a NEMA 5-15Pplugfor 117VAC
operation. The AL-80A can be modified for 234 VAGopera-
tion. Ifyoudesire to makethis modification,twojumper wires
must be movedto new locations on the terminal block. (see
illustration below) The terminal block is located on the left
side of the rear panel.
The wiring betweenthe fuse box andthe amplifier AC. outlet
must be No. 12 gauge or larger in order to supply the cur-
rent required (15 amperes) without a significant drop in line
voltage. The 117V outlet should be fused for 20 amperes.
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117 VOLT OPERATION 234 VOLT OPERATION
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ALC
Use a shielded audio-type cable to connect the 0-20 volt
negative ALC voltage to the transmitter ALC input. Consult
the transmitter manual for proper connection details. The
amplifier must be properly tuned on CW before adjusting the
ALC. '
Proper adjustment is achieved as follows:
1. Set the MULTIMETER switch to the PO position.
2. Set the transmitter audio control about 20% higher
than normal.
3. Speak into the microphone in a normal tone of
voice and observe the reading on the 0-2000 R.F.
Watts scale.
4. Adjust the ALC ADJ control on the rear panel until the
amplifier is not clipping on an RF scope.
5. If an RF scope is not available, adjust the ALC control so
the audio peaks do not exceed the single tone output of
1000 watts.
METERING FUNCTIONS
The AL-80Ahas two illuminated panel meters.The Grid Cur-
rent meter provides a continous reading of grid current. This
is an exclusive feature of Ameritron amplifiers. Grid current
will indicate proper operation of the amplifier better than any
other parameter. Do not exceed 200 mA on this meter dur-
ing operation of the amplifier. The other meter reads Plate
Voltage (HV), Plate Current (Ip), Peak R.F. Watts (PO) and
ALC. The functions are explained as follows:
PLATE VOLTAGE (HV): Read D.C. Plate Voltage on the
0-3500 Volt scale. This scale is 100 volts per division. Nor-
mal voltages are 3100 volts no load, 2700 volts full load.
PLATECURRENT(Ip):Read PlateCurrent onthe 0-700mA
scale. This scale is 20 mA per division. The average
operating current rating of the 3-500z is 400 mA maximum.
PEAK R.F. WATTS (PO): Read Peak R.F. Watts on the
0-2000 scale. The scale has 50 watt divisions below 1000
watts and 100 watt divisions above 1000 watts.
ALC: In this position the meter indicates the ALC detector
voltage. It provides a relative drive level indication of 200
watts full scale. The approximate drive level (average, not
PEP)can be estimated by dividing the Peak R.F. Wattsscale
by 10.
IMPORT ANT
Do not make any modifications to the AL-80A cir-
cuit before checking with our engineering staff.
Improper changes may damage the AL-80A'and void
the warranty.
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RF OUT RELAY
Transmitter or
Transceiver
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Connection Diagram ]
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1
ALC
To Antenna
RFOUT ~I
RF IN AL80A
-
RELAY
ALC OUT
@ALC ADJ @
@12V GND 10 AMP
ONLY
@
To Earth
Ground
INSTAllATION
Connect the RF output of the transmitter to the RF IN
connector onthe rearof the Al-80A with 50 ohm coax. Con-
nect the existing station antenna system to the RF OUT con-
nector on the Al-80A with RG-8 type coax. Connect the
RELAY phono jack on the rear of the Al-80A to the normal-
ly open terminals of the RELAYjack on the transmitter. The
RELAYjack on the Al-80A has positive 12VDC open circuit
and provides 100MAof current when pulled to ground. Con-
nect as short a ground lead as possible from a good earth
ground to the GND terminal.
The 12V connection on the rear panel provides 12 VDC at
100 MA maximum to operate external dial lamps or
accessories.
2
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MUL TIMETER GRID METER
PLATE
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AL-80A
AMPLIFIER
BAND
40
PLATE CURRENT
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GRID CURRENT
MULTIMETER XMT 0
LOAD
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2" II 8
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IP, ,PO
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0PWR OPR 0": :"10 '1
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OFF
.1.
pOWER
SWITCH
STBY
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OPERATE-
STANDBY
SWITCH
TUNING INSTRUCTIONS
Follow the instructions in numerical order. If the various meter readings are different than indicated in the instructions,
check the connections from the exciter to the amplifier and make sure they are correct. Consult the manual for the
exciter if necessary.
1. Set the AL-80A front panel switches as follows:
PWR -OFF to OFF
OPR - STBY to STBY
MULTIMETER to HV
2. Plug the A.C. line cord into the proper voltage outlet. The AL-80A is factory wired for 117VAC50/60 Hz operation.
3. Set the PWR-OFF switch to PWR. The meter lamps should light and the blower should start. Read the 0-3500V
scale on the multimeter. It should indicate 3100 volts nominal.
4. With the amplifier still on standby, tune the exciter into the normal 50 ohm load according to the manufacturer's
instructions. Turn the exciter drive fully down after tuning.
5. Place the bandswitch on the same band as the exciter, the PLATE tuning control in the dial range for the band
selected and the LOAD control at the recommended point for the band in use.
6. With the exciter drive still at zero, place the MULTIMETER switch in the Ip position. Observe the 0-700 mA scale.
It should read zero. Place the STBY-OPR switch in the OPR position.
3
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7. Key the exciter (no drive) and observe the plate current on the 0-700 mA scale. Plate current should now read
.between 50 mA and 100 mA.
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8. Apply only enough drive to indicate a grid current of 50 mA or an Ip of no more than 200 mA. Tune the PLATE", /r-'
control for maximum grid current. Itis normal for the plate current to dip at this point. Ifthe grid current goes over
100 mA reduce the drive at once. Unkey the exciter.
9. Place the MUL TIMETER switch inthe PO positionand observe the 0-2000 peak RF. watts scale.Apply the same
drive again and adjust the LOAD and PLATE controlsfor maximum output on the 0-2000 scale.
10. Increase the drive until 125mA of grid current is indicated. Adjust the LOAD and PLATE controls again for max-
imum output. The grid current will be lower now.
11. Advance the drive to 200 mA of grid current. Adjust the LOAD and PLATE controls for maximum output power.
(Repeat this step twice.) The output should be around 1000-watts now with 100 watts of exciter power.
12. Apply enough drive to indicate either 1000 watts of output power or 200 mA of grid current. Re-peak the LOAD
and PLATE controls. The grid current must not be over 200 mA, the plate current over 550mA or the output over
1200 watts.
13. In CW operation the drive power should be reduced until the plate current is 400 mA or less.'F6r"5S~ operation
the modulation crest should not exceed 400 mA plate current, 100 mA grid current or 1200 watts PEP output.
The AL-80A will operate with full output on all WARC bands except 24.5 MHz. The
AL-80AX (export model) will operate with full output on all WARC bands.
STANDARD FREQUENCY COVERAGE
4,
TUNING CHART (Typical)
FREQUENCY BANDSWITCH PLATE CONTROL LOAD CONTROL
1.85 160 160 4
3.5 80 80 1
3.8 80 80 3
7.2 40 40 5
14.2 20 20 5
21.2 15 15 7
';c 24.5 10 20 7
*28.7 10 15 8
.::AL-80AX (export model)
AL-80A AL-80AX
160 meters 1.8-2.0MHz 160 meters 1.8-2.0MHz
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 9.5-15.5 MHz 20 meters 9.5-15.5 MHz
15 meters 15.5-21.5 MHz 15 meters 15.5-21.5 MHz
10 meters 24-29 MHz

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R3
R5
R7
B- HVM
Dl
CI, C3
C2
C4
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SI
1,5 AMP 50V bridge(AR-646)
.0luf50Vdisc (AR-416)
1000uf 25V (AR-149)
10uf 25V (AR-642)
2N3904 (AR-645)
2-6 pas. rotary (AR-563)
switch
A.C.
ALC
IN
METER BOARD FP-160
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SI
R9
B-
HV
BRESISTORS,50K OHMS, 7W, 5% (AR-580) ,
HVM
47K OHMS, l/2W, 5% -I
(AR-402)
2 RESISTORS 1M OHMS, 2W, 1% (AR-223)
1 RESISTOR 1.5M OHMS, 2W, 1% (AR-IS?)
FILTER CAPACITOR BOARD FP-163
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A.C.
ALL CAPACITORS
.01 uF 1 KV DISC
(AR-l2l)
ALL DIODES 1N5408
1000V 3 AMP
(AR-145)
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R.F.
OUT ALC
CONTROL R.F.
IN
t,
R3
C2
P.O.
ALC
(AR-404) (1
(AR-396) (2, C7
(AR-416) A, C4
IAR-53') CS, C6
27 pf Silver Mica
150 pf Silver Mica
.01 uf Disc Ceramic
10 pf Silver Mica
(AR-346) Dl-D4 IN 34 or IN 118 Diode
(AR-402) Rl 47K ohm, 1/2 W, 5%
(AR-384) R2, R3 180 ohm, 1/2 W, 5%
ALC/POWER BOARD FP-162
Lon
12V' AUX 12V AC AC
RI, .6 ohm 3W 1% (AR-399)
R3, 1.50hm3WI% (AR-400)
R5 100 K ohm trimpot (AR-534)
R6 33 K ohm 1/2 W 5% (AR-644)
R7 15Kohm 1/2 W 5% (AR-273)
RB 10Kohm 1/2 W 5% (AR-643)
R9 10ohm 1/2 W film type (AR-595)