AMERITRON AL-80A User manual

AMERITRON AL-80A
HIGH POWER
LINEAR AMPLIFIER
INSTRUCTION MANUAL
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 AB 2 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.
DIVrSION OF
PRIME INSTRUMENTS, INC.
9805 Walford Avenue • Cleveland, Ohio 44102
Printed in U.S.A.
F-1035

VENTILATION
The AL-80A ventilation system has been designed and tested
to maintain tube seal temperatures safely below the tube
manufacturer’s rating when operated within our guidelines.
To insure proper ventilation in your installation, observe the
following:
1. Do not block or restrict the ventilation holes in the
cover.
2. The exhaust air flow is over 50 CFM. Do not “assist” the
air flow unless the fan used exceeds the AL-80A blower
CFM by a factor of 2:1.
3. Do not mount additional fans on the AL-80A cabinet.
4. The exhaust air will become quite warm at high
power levels. Do not place any heat sensitive objects
in the exhaust air stream.
POWER CONNECTIONS
The AL-80A is supplied with a NEMA 5-15P plug for 117 VAC
operation. The AL-80A can be modified for 234 VAC opera¬
tion. If you desire to make this modification, two jumper wires
must be moved to new locations on the terminal block, (see
illustration below) The terminal block is located on the left
side of the rear panel.
The wiring between the fuse box and the amplifier A.C. 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.
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-80A has 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.
plate current (Ip): Read Plate Current on the 0-700 mA
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. Watts scale
by 10.
IMPORTANT
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.

Connection Diagram
To Antenno
RF OUT
RFOUT RELAY ALC
Trans mit te r or
Transceiver
INSTALLATION
Connect the RF output of the transmitter to the RF IN
connector on the rear of 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 RELAY jack on the transmitter. The
RELAY jack on the AL-80A has positive 12 VDC open circuit
and provides 100 MAof 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

POWER OPERATE-
SWITCH 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 117VAC 50/60 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

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.
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
control for maximum grid current. It is normal for the plate current to dip at this point. If the grid current goes over
100 mA reduce the drive at once. Unkey the exciter.
9. Place the MULTIMETER switch in the PO position and observe the 0-2000 peak R.F. watts scale. Apply the same
drive again and adjust the LOAD and PLATE controls for 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. For SSB operation
the modulation crest should not exceed 400 mA plate current, 100 mA grid current or 1200 watts PEP output.
TUNING
CHART (Typical)
FREQUENCY BANDSWITCH
PLATE CONTROL
LOAD CONTROL
1.85
160
160
4
3.5 80 80
ih
3.8 80 80
3h
7.2 40 40
5
14.2 20 20
5^
21.2 15
15
IH
-:'r2 4.5
10 20
1
*28.7
10 15
8
AL-80AX (export model)
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
AL-80A
AL-80AX
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
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
4

c* cw I T i» o
AL-80A SCHEMATIC
^r* Tr»
Bit, »f>./Wht ^
r\ ^ Bit, •
Blk/Wht J I I >
BIkjJwht t«d
nh
U t - HVM
-T-T-T
BANDSWITCH SHOWN IN
160 MtTE* POSITION
REAR VIEW
AL-80A Tuned Input Chart
Input
C 18pf
Output
C 19pf
160
3300
(AR-690)
28t.
(FP-149) 2700
(AR-689)
80
1000
(AR-176)
21t.
(FP-150) 820
(AR-381)
40
500
(AR-691)
I4'',t.
(FP-151) 360
(AR-683)
20
220
{AR-175)
9>,t.
(FP-152) 120
(AR-606)
15
150
(AR-396)
5'.t.
(FP-153)
68
(AR-395)
10*
100
(AR-174)
3'.t.
(FP-154)
27
(AR-404)
*Export model.s only
PARTS LIST
B 1
C 1,2,3
C 4,5
C 6,7,8,9
C 10,11,12
C 13
C 14
C 15,17
C 16
C 18,19
D 1
F 1,2
FP-160
FP-161
FP-162
FP-163
L 1
L 2
TA-450S Fan ftA30390-10 (AR-138)
.01 uf 50V disc (AR-416)
.01 uf 1.4 KV disc (AR-122
.01 uf 1 KV disc (AR-121)
.001 uf 7.5 KV disc (AR-224)
Plate tuning 250 pf .075" spacing variable (AR-112)
Loading 800 pf 1.2 KV variable {AR-573)
170 pf N750,850 series doorknob (AR-559)
500 pf, 850 series doorknob (AR-412)
See input chart
Green L.E.D. (AR-523)
10 amp fuse 3AG {AR-150)
Meter board assembly
H.V. rectifier board assanbly
P.O./ALC detector board assenbly
H.V. filter capacitor board assembly
H.F. coil 8 ga. tin plated (FP-164)
L.F. coil 2" I.D. #12 airdux (AR-669)
"L" coil T 200-2 toroidal core (FP-165)
See input chart
Multimeter, 0-1 mA 420 ohm {AR-692)
Grid meter, 0-1 mA 450 ohm (AR-693)
Parasitic choke and plate cap assembly (FP-11
47K ohm, watt carbon (AR-402)
33 ohm, watt carbon (AR-403)
Filament choke (FP-115)
Plate Choke (FP-139)
Safety choke (AR-162)
3 PDT lOA relay, 12 VDC (AR-139)
Bandswitch (AR-136-2)
Rocker switch (AR-147)
Interlock switch (AR-247)
Power transformer (AR-109-2)
3-500Z tube (AR-167)
lOOK ohm, watt ALC control (AR-274)
12V wire lead meter lamps (AR-164)
7.5V 10 watt anode to case (AR-604)

DIVISION OF
PRIME INSTRUMENTS, INC.
9805 Walford Ave. • Cleveland, Ohio 44102 • 216/651-1740
SYMBOL OF ENGINEERING INTEGRITY ... QUALITY
WORKMANSHIP ... RELIABLE LONG-LIFE PERFORMANCE
TECHNICAL SPECIFICATIONS AL-80A
Input
circuit type; Pi-network
maximum VSWR at resonance; 1.3;1 or less
minimum 2;1 VSWR bandwidth; 20% or greater
maximum drive power permissible; 100 w
typical drive for full power output; 85 w
Output
circuit type; Pi-L network
h hour continuous carrier; 500 watts
30 second continuous carrier; 850 watts
h hour PEP two-tone test; 850 watts
30 second PEP two-tone test; 1000 watts
Power Supply
circuit type; voltage doubler
no load voltage; 3000
full load voltage; 2700
full load current; .450 amp
regulation; 10%
transformer; 22 lbs.
capacitors; computer grade, 26 mfd total
maximum draw at rated output; 12 amps at 120 v 50/60 Hz

Tube
type; 3-500Z
continuous dissipation; 500 w
warm-up time; 10 seconds
estimated life; 20,000 hours
factory cost; $90.00
Metering; dual meters; plate volts, plate current, grid current,
power output PEP
ALC; adjustable, 0-20 v, negative going, phono jack
Efficiency CW; =70%
Efficiency SSB (envelope crest); =70%
MARS/WARC; yes, set to nearest amateur band
Keying; requires contact closure or sink of +12 VDC at 100 mA, phono
jack
RF Connectors; S0239
Line Connector; NEMA 5-15P, standard 120 v three wire
Dimensions; IS^s” D. x 14*5" W. x 8" H. ,
Weight; 60 lbs.
Frequency Coverage; all amateur bands from 1.8 to 21 MHz, including
WARC and most MARS
Third Order IMD at Rated Output; -35 dB

AL-80A
UNPACKING INSTRUCTIONS
Carefully lift th« ampUfUr out of Rtmovo tho PhilUpt screws holdin
the pecking materiel. Examine it for the cover on. Slide the cover bac
visible damage. If the amplifier has and remove it from the amplifUr.
been damaged in shipment, notify the
transportation company. Remove the packing material from th
plate cap assembly.
TUBE INSTALLATION
Insert the 3-500* tube into the sock¬
et on the amplifier chassis. Install
the plate cap connector on the tube
cap and secure it in place with the
screw provided. BE SORE the solder
lug is on the underside of the connec¬
tor - see illustration, oo NOT over¬
tighten the screw. Replace the am¬
plifier cover and the 13 screws that
secure it. The additional screws are
attached to these instructions.
IMNOtTANT
Save all the hardware and packing materials in
case you ever need to return your AL-BOR for
factory service. Any units returned without
proper packing may be imaged and shipping
claims cannot be made.
Never ship the amplifier with the tube installed.
fP-l0l2A

DIVISION OF
PRIME INSTRUMENTS, INC.
9805 Walford Ava. • Clavaland, Ohio 44102 • 216W51-1740
THIS AMPLIFIER HAS AH OPTIONAL MULTI-VOLTAGE TRANSFORMER.
FOR OPERATION ON VOLTAGES OTHER THAN THE DESIGN CENTER THE BUCK-
BOOST WINDING CAN BE USED TO IMPROVE PERFORMANCE.
DO NOT EXCEED 3200 VOLTS HIGH VOLTAGE!
S.
VOLTAGE
//5yg.? C
C.
VOLTAGE
110/23 0
FREQUENCY GO Hz / SOH7
aTl

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