Kenwood TL-922A User manual

QKENWOOD
LINEAR AMPLIFIER
Model TL-922A
INSTRUCTION MANUAL

AFTER UNPACKING
It is advisable to save all original packing cartons (inner and
outer) to protect your valuable Linear Amplifier from
damage should you wish to transport it for remote opera-
tion or ship it for after-sales service.
The following explicit definitions apply in this manual. Be
sure to read these definitions:
NOTE = If disregarded, inconvenience only — no
damage or personal injury.
CAUTION = equipment damage may occur, but not
personal injury.
WARNING = personal injury may occur — do not dis-
regard.
CONTENTS
TL-922A SPECIFICATIONS . .
SECTION 1 FEATURES .. . .
SECTION 2. PREPARATION FOR USE
2.1 Accessories
2.2 Installation of Power Tubes
2.3 General Tips on Installation
2.4 AC Power Source
2.5 Line Voltage Change
2.6 Power Cable
2.7 Exciter
2.8 Antenna
2.9 Interconnection
2.9.1 Grounding
2.9.2 Cable Connection
SECTION 3 CONTROLS AND THEIR FUNCTIONS . 9
3.1 Front Panel
3.2 Rear Panel
SECTION 4 OPERATION ...... wee ee ee eeeee 11
4.1 Prechecks
4.2. CW Operation
4.3 SSB Operation
4.4 RTTY Operation
4.5 Setting the ALC ADJ Control
4.6 Adjusting the RF Output Meter
4.7 High-Voltage Transformer Protection
4.8 Carrying Your TL-9224
SECTIONS CIRCUIT DESCRIPTION......... 13
5.1 Linear Power Amplifier
5.2 Power Supply
5.3 Fan Motor Delay Stop Circuit
5.4 Meter Drive Circuit
5.5 Spark Suppressor
CAUTION
Read Operating Manual Section 2 before proceeding to
unpack and assemble your amplifier.
WARNING
LETHAL VOLTAGES PRESENT.
SECTION 6 MAINTENANCE...............- 15
6.1 Internal Cleaning
6.2 Replacing Power Fuses
6.3 Replacing Power Tubes
6.4 Input Matching Circuit
SECTION 7 TROUBLESHOOTING HINTS .
PACKING: iiss:0 ics eis Sa tower aa oat
ILLUSTRATIONS
Fig. 2-1 Upper Case Cover Assembly/
Disassembly ............. 5
Fig. 2-2 Correct Power Tube Handling 5
Fig. 2-3 Parasitic Suppressor Coil Mounting 6
Fig. 2-4 Input Voltage Terminal Boards 7
Fig. 2-5 Power Cable Color Code . . 8
Fig. 2-6 Exciter Connections for RL and ALC
Controls ......... oii eee » 8
Fig.
2-7
Interconnection
of
the
TL-922A
......
8
Fig. 3-1 Front View....... beciegtsade hice) 8
Fig. 3-2 Rear View Cees eae eehae es . 10
Fig.
5-1
Linear
Power
Amplifier
Circuit
.......
13
Fig. 5-2 Transformer Primary Current Flow..... 14
Fig. 5-3. Fan Mogpr Delay Stop Circuit ........ 14
Fig. 5-4 Meter Drive Circuit................ 14
Fig. 7-1 Packing for Shipment . 17
Fig. 7-2,3Top, Bottom Views 18
TABLES
1.
Front Panel
Controls
Set-Up
..............
11
2.
Tune
and
Load
Initial
Settings
.............
11

Transmit Frequency Range:
Excitation Energy Required:
Mode and Duty Cycle:
Rated Plate Input:
Plate Voltage: (at No signal)
Circuit Type:
3rd Order Intermodulation Distortion:
Input Impedance:
Output Impedance:
Cooling:
Interlock Safety Features:
Thermal Protector:
Fan Motor Delay Stop Time:
ALC:
Power Tubes Used:
Semiconductors:
Power Requirements:
Cables Supplied:
Dimensions:
Weight:
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TL-922A SPECIFICATIONS
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160m through 15m Amateur Bands
80 W nominal, 120 W maximum
SSB, continuous for 30 minutes.
CW and RTTY, key-down continuous for 10 minutes.
2 kW P.E.P. SSB, 1 kW CW RTTY
3.1 kV SSB, 2.2 kV CW RTTY
Class AB2 grounded grid linear amplifier
Below —30dB.
50 2, unbalanced at better than 1.5 SWR
50 to 75 2, unbalanced.
Forced Air.
Primary high voltage circuit cut-off.
Secondary high-voltage circuit grounding.
Locks out transmit relays if H.V. power transformer overheats.
140 + 30 seconds. (at room temperature)
Negative going, adjustable threshold -8V DC maximum output (typical).
Eimac 3-500Z, two pieces
Diodes, 18 pieces
Zener diode, 1 piece
120V, 28A; 240V, 14A; 50/60Hz; for maximum SSB input.
Signal cable (coaxial) with UHF-type connector, 1.5m.
Control cable, 1.5m.
390mm x 190mm x 407 mm (15-3/8 x 7-1/2 x 16”)
Net 31 kg (68 Ibs.)
Shipping 38 kg (83 Ibs.)
The above specifications are subject to change without notice due to technical im-
provement.

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The TL-922A is a Class AB2, grounded grid linear
amplifier developed by Trio-Kenwood through ad-
vanced high-power technology using two high-per-
formance Eimac 3-500Z power tubes. It covers all
bands 160 m through 15 m for SSB, CW and RTTY
modes of operation.
Unprecedented Reliability
The TL-922A is designed to provide stable, high RF
output power for extended periods of continuous use.
Engineered with Trio-Kenwood’s advanced circuit and
mechanical technology, the TL-922A employs two
rugged 3-500Z power tubes to their full advantage.
Low Intermodulation Distortion
Intermodulation distortion (IMD) is minimized
through the use of negative R.F. feedback.
Quick Turn-On
Warm-up is not necessary. The 3-500Z tubes are fast
heating.
Full Safety System
To protect you against any possible high voltage elect-
ric shock, your TL-922A has a double safety system
comprised of interlocking switches. One interrupts
the high voltage primary circuit while the second
directly grounds the secondary high voltage circuit.
Also provided are bleeder resistors for discharging the
high voltage capacitors and “DANGER” warnings at
high voltage positions. Please observe all warnings,
they are for your protection.
Newly-Developed Fan Motor Delay Stop Circuit
To reduce power tube deterioration, your TL-922A
has a newly-developed fan motor delay-stop circuit
comprised of a thermal delay relay. The cooling fan
will normally run for 140 seconds (Typ) after power
is removed from the unit and will measurably ex-
tended tube life.
Mode Switch for Efficient Linear Operation
MODE switching is provided to select between the
SSB Mode for the maximum PEP output with good
SECTION 1. FEATURES
sustenance canna ta
10.
11.
12.
13.
linearity, and the CW Mode for low power consump-
tion and heat generation during extended periods of
operation.
Linear Amplification Control Switch
This switch is capable of setting your TL-922A in the
straight-through state irrespective of the standby
control on the exciter.
Variable Threshold Level (ALC Detector)
The ALC circuit will accommodate exciters of 80 w
to 120 w (nominal) by varying the ALC threshold
level. This effectively prevents overdriving the final
power tubes, limiting the Amplifier to its linear range
and guaranteeing low distortion at maximum power.
Two Panel Meters
In adjusting or monitoring your TL-922A, one meter
always indicates the (Ip) plate current; while, with the
other, you may read (Ig) grid current, (RF) relative
output, or (HV) high voltage. This facilitates ease of
operation of your TL-922A.
Rigid Mechanical Structure
The die-cast side panels effectively support the weight
of the amplifier against shocks and jarring during
transportation. Recessed side panel handles are pro-
vided so the Amplifier can be easily carried.
Vernier Plate Tuning Dial
The PLATE tune dial is equipped with a reduction
gear that facilitates easy tuning, particularly for the
higher bands. It also effectively prevents accidental
miss-tuning during operation. Controls and panel
arrangement, designed to human _ engineering
standards, provide superior ease of operation.
Neat, Contemporary Appearance
Mechanical arrangement and sophisticated design to
match any Trio-Kenwood transceiver or transmitter.
Your TL-922A can also be used as a high-quality,
general purpose Amateur band linear amplifier with
any exciter capable of 8OW to 120W RF output.

2.1 ACCESSORIES
Carefully unpack your TL-922A Linear Amplifier and
check that it is supplied with the following accessories.
1, Instruction manual B50-2587-00 1 copy
2. Coaxial cable, 1.5m, with UHF-type
connectors X42- 1100-00 1 piece
3. Control cableW/8Pin Plug 1 piece
(For TS-520, TS-820 Series)
X42-1110-10
4. Control cable W/7 Pin Plug 1 piece
(For TS-120, TS-130, TS-180, TS-430,
TS-530, TS-830, TS-930 Series) X42-1110-11
5. Spare fuse, 15A FO5-1533-05 2 pieces
6. Extension foot JO2-0049-14 2 pieces
7. Screws, 4 x 12mm long N30-4012-46 2 pieces
8. Plate cap FO2-0407-04 2 pieces
9. Parasitic suppressor coil, right hand 1 piece
L39-0401-05
10. Parasitic suppressor coil, left hand 1 piece
L39-0402-05
11. Screw, 3 x 6mm long N30-3006-46 4 pieces
12. Plain washer N15-1030-46 4 pieces
13. Spring washer N16-0030-46 4 pieces
2.2 INSTALLATION OF POWER TUBES
To protect the power tubes in your TL-922A against
vibration and shock during transport, they were packed
separately from the amplifier. For insertion, follow the
procedures below. Prepare the following mounting
hardware and tools:
Mounting Hardware
Power tube, 3-500Z 2 pieces
Plate cap 2 pieces
Parasitic suppressor coil, right hand
and left hand 1 piece each
Screw, 3 x 6 mm long 4 pieces
Plain washer 4 pieces
Spring washer 4 pieces
Tools
Phillips screwdriver 1 piece
Small standard screwdriver 1 piece
NOTE: A parts tray to prevent loss of metric hardware is
helpful.
WARNING: Before proceeding, make sure that:
The power cable is NOT plugged in the wall out-
let. The METER switch is at the HV position
and the multimeter reads OV.
Proceed as follows: (Refer to Fig. 2-1)
1. Remove the four 4 mm Phillips screws holding the
upper case cover.
2. Remove the upper case cover.
3. Remove the four 3 mm self-tapping Phillips screws
and four flat head self-tapping Phillips screws holding
the inside shield on the power tube enclosure.
Se ee
SECTION 2. PREPARATION FOR USE
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Remove the shield plate.
5. Take the tubes out of their case (Refer to Fig. 2-2). In
handling, be sure to hold them by the glass envelope,
not the plate cap.
6. Carefully index the pins of each tube into its socket
and insert gently without excessive force.
INSERT UPPER 4mm
CASE COVER r ia v ical
LEADING EDGE
INTO FRONT |
PANEL TOP LIP
HIGH VOLTAGE |
PRIMARY PROTECTION
SWITCH PLUNGER }
3mm FLAT HEAD Z
SELF-TAPPING \, wT | ¥
SCREW (4 PCS) B an
cree
INsiDe 42
HIGH VOLTAGE | 184
! : [SHIELD PALTE
SECONDARY
PROTECTION
SWITCH |
PLUNGER.
UPPER CASE Figure 2-1
COVER
INSERT
Upper
Case
Cover
D ata \2 Assembly/Disassembly.
SWITCH USE #2 Phillips
PLUNGER Screwdriver.
Figure 2-2 — Correct Power
Tube Handling

CAUTION
Particular care should be taken not to strike and
break the glass tubes during installation. Tube break-
age due to negligence is not warranteed
th (Refer to Fig. 2-3) Temporarily fix each parasitic sup-
pressor coil on the plate cap with the letter “R’” or “L”
facing up. At this time, do not tighten the 4 mm screw
and spring washer, but snug them so the coil may be
adjusted.
8. Mount the plate cap with parasitic suppressor coil on
each tube observing the right hand and left hand coil
designations. If the screw holes do not align, shape
the coil by slight bending or extending by hand for
precise installation, keeping the coil below the level
of the plate cap.
CAUTION: Particular care should be exercised in not
applying excessive force to the tubes.
9. Carefully tighten the screws at each end of the coil
while holding the plate cap by hand.
10. Tighten the plate cap screw using the small standard
screwdriver.
11, Check to assure correct installation by reference to
Fig. 3-3.
NOTE:
1: Before installation, check each parasitic suppressor coil for
good alignment to prevent the application of excessive force
to the tubes.
: Letters “'R’ and “’L” on the coils should face up.
: Temporarily install each coil on their plate caps before final
tightening. Use # Philips screwdriver.
Figure 2-3 — Parasitic Suppressor Coil Mounting
Tube Installation Checkout
1. To avoid damage necessitating tube replacement,
please check:
a. Power tubes are free from scratches or other
physical defects.
Tubes are fully inserted into their sockets.
Plate cap screws tightened securely.
d. — Screws at both ends of the parasitic suppressor
coils are tightened securely.
e. Washers, screws, drivers and any other unneces-
sary material is not left inside the unit.
ra Refer to Fig. 2-1. The inside shield plate includes the
high voltage secondary protection switch plunger (a
bakelite bar.) Position the plate so that the plunger will
securely engage the spring plate for ungrounding the
plate high voltage.
3. Install the upper case cover with its leading edge in-
serted (approximately 1 mm) into the front panel lip.
This cover has the high voltage primary protective
switch plunger. Position the cover so the plunger will
engage the microswitch.
os
2.3. GENERAL TIPS ON INSTALLATION
Install in a dry, well-ventilated area, shaded from direct
Sunslight. Your TL-922A must have a minimum
clearance of 15 cm to the rear to allow hot air at 50 to
70°C to exhaust.
Choose an operating position capable of safely supporting
the weight of the TL-922A (31 kg), plus all the other
station equipment.
Level your TL-922A in operation. The heated electrodes in
each power tube will be distorted by gravity resulting in
shortened service life, if slanted beyond 10°.
2.4 AC POWER SOURCE
Use an AC power line having sufficient current capacity
or the performance of your TL-922A will be adversely
affected by inadequate line regulation. In the worst case,
do not deviate more than +10% from the rated input
voltage for which your Amplifier has been set.
2.5 LINE VOLTAGE CHANGE
WARNING
DISCONNECT THE AC INPUT POWER CABLE
FROM THE TL-922A BEFORE PROCEEDING.
The input voltage can be changed to either 240V or 120V as
required, by changing the power transformer input links
located in the duct on the rear panel.
NOTE: The TL:922A was factory set in the 240V position.

To change link positions, remove the access cover by the
two black snap fasteners. Loosen the screws holding the
shorting bars, a few turns only. (Do not loosen excessively
as they could drop into the Amplifier.) Draw each shorting
bar upward for removal. Replace the shorting bars for the
operating voltage desired as illustrated in Fig. 2-4. Tighten
firmly. Also, be sure to tighten the screws from which the
shorting bars were removed.
NOTE: Fuses need not be changed in current rating when
the input voltage is changed.
CAUTION: Excess force may break the terminal strip.
2.6 POWER CABLE
The power cable supplied with your TL-922A has no plug
at its end. Connect a plug mating with the wall outlet.
The blue and brown leads are power, the green lead ground
as illustrated in Figure 2-5.
2.7 EXCITER
An HF Amateur band SSB or CW transmitter or transceiver
having an RF output impedance of 502 and output power of
80W to 120W is sufficient to drive the TL-922A. Exciter
output exceeding 120W will cause overdrive, resulting in
shortened power tube life and distorted output. To limit the
power level above 120W, use an exciter having an external
ALC input terminal.
CAUTION: BE SURE TO TIGHTEN ALL
LOOSENED SCREWS.
Use # Philips screwdriver.
Spare shorting bars
are secured at terminals 3 and 4.
a: 240V setting
b: 120V setting
Figure 2-4 — Input Voltage Terminal Boards
Trio-Kenwood's transceivers Series TS-930, TS-830,
TS-820, TS-530, TS-520, TS-430, TS-180, TS-130,
TS-120 and TS-900 and transmitters Series TX/T-599
are all suitable exciters and will match the TL-922A in de-
sign as well as appearance.
2.8 ANTENNA
Your TL-922A requires an antenna having a 50 to 752
impedance and providing it is:
(1) Rated for 2 kW P.E-P input power
(2) and, exhibits a low standing-wave ratio (SWR)
Desired SWR is 1.5 to 1. or less. A higher SWR, 2 or
3 to 1, may cause difficult matching with your TL-
922A. Excessive SWR could melt the coaxial cable
and antenna. To protect your TL-922A against
adverse SWR effects, use an antenna tuner. Note that
feeder radiation due to mismatching will cause TVI,
BCI, or similar RFI.
BLUE
BROWN
TO
240/120V
LINE
TO GROUND
GREEN
Figure 2-5 — Power Cable Color Code
EXCITER
TbooA
TRANSMIT
|
RL
CONTROL!
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RELAY POWER
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SOURCE
RECEIVE
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CONTROL
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Figure 2-6
Exciter Connections for RL and ALC Controls.

2.9 INTERCONNECTION
2.9.1 GROUNDING
Connect the GND posts of the TL-922A and
exciter
RFI.
to prevent possible electric shock and
The wire used should be as thick and
short as possible and run to a good earth ground.
2.9.2 CABLE CONNECTION
Interconnect your TL-922A and exciter with the
supplied cables as illustrated in Figure 2-7.
NOTE:
If you use an exciter of another brand,
replace the supplied connector with one
appropriate to your exciter. The exciter
used must accept the negative-going ALC
voltage from the TL-922A.
(The ALC output at no signal input is
normally positive when not connected to
the exciter.)
The RL, or standby control, in the exciter must be
switched to ground in transmit mode, as illustrated
in Figure 2-6.
NOTE: Use RG-8/U, RG-11/U or heavier as
antenna cable.
NOTE: If an SWR meter is connected between
the TL-922A and the exciter, total co-
axial cable length must not exceed 1.7 m.

7 8 9 1
10
Figure 3-1 Front Panel View
3.1 FRONT PANEL
1.
IP Meter
The IP meter reads the plate current flowing through
the power tubes.
ON AIR Indicator
The ON AIR indicator lights up in the on-the-air,
or transmit MODE.
PLATE Tuning Control
This control permits you to tune the plate circuit to
the desired transmit frequency, and is equipped with a
reduction gear for easy tuning.
Multimeter
The Multimeter can read the Ig (grid current), RF
(relative power output), or HV (plate voltage) as
selected by the METER switch
STBY Indicator
With the unit turned on, shows unkeyed or receive
state.
LOAD Control
Impedance matches the pi network to the antenna.
POWER Switch
A double pole switch completely disconnects the AC
input from the transformers.
MODE Switch
Set for SSB or CW. For RTTY operation, set the
switch to the CW position.
10.
11,
METER Switch
Selects Ig (grid current), RF (relative power output), or
HV (plate voltage).
BAND Selector
Set for the Amateur band in which operation is
desired.
LINEAR Switch
In the STBY position, the exciter runs straight
through. In the OPERATE position, the Amplifier
automatically keys with the exciter.

5 6 7 10 8
Figure 3-2 Rear Panel View
3.2 REAR PANEL
1.
Cooling Fan
The Cooling Fan cools the power tubes and effectively
keeps the inside temperature from increasing. Be
careful of hot air (50° to 70°C) at the exhaust port.
Line Voltage Change Terminals
These terminals are located behind the rear cover,
which is removed by pulling the two snap fasteners.
For input voltage change, please refer to Section 2.5.
Serial No. Plate
This plate is stamped with the Serial Number of your
TL-922A.
RF METER Control
This control is used to calibrate the RF output read-
ing. For calibration, see Section 4.6.
ALC ADJ Control
This control is used to adjust the ALC voltage. For
adjustment, see Section 4.5.
ALC OUT Jack
This jack feeds the ALC voltage out.
RL CONT Jack
This jack inputs the transmit-receive relay switching
ground from the exciter
10.
11.
12.
RF INPUT Connector
This UHF-type connector inputs the RF signal fed
from the exciter. Use the supplied cable.
RF OUTPUT Connector
This UHF-type connector feeds the RF output to
the antenna.
GND Post
Use this post to ground the TL-922A to your exciter
and station ground.
FUSE Holders (2)
Each contains a 15 A fuse. If either or both fuses are
blown, determine the cause before replacement.
POWER Cable
AC power is supplied to the amplifier by a three-wire
cable. (See section 2.6)

4.1 PRECHECKS
If you are a newcomer to this type of equipment, or if you
have replaced a power tube, you should first assure yourself
of the following before connection of power and turn on:
a Power tubes are installed correctly.
Verify tube installation checkout with Section 2.2.
b. The upper case cover and inside shield plate are cor-
rectly installed per Section 2.2.
The upper case cover controls the high voltage
primary protection circuit. This circuit also controls
the fan motor power. The inside shield plate controls
the high voltage protection circuit, grounding the HV
supply, which will immediately blow the power fuses
if incorrectly installed. Particular care should be ex-
ercised when installing the inside shield plate. In addi-
tion, the upper case cover and inside shield plate are
needed for heat-sinking the interior of your TL-
922A. For installation of these plates, please refer to
Section 2.2, “How To Install Power Tubes.”
e Line voltage change terminals are properly bridged for
your local Line voltage.
Refer to Section 2.5 ‘‘Line Voltage Change.”
d. Make certain that the exciter, antenna and ground
wires are connected properly. Verify that the POWER
switch on your TL-922A is in the OFF position BE-
FORE CONNECTING the AC power cable.
e Set the front panel controls of your TL-922A as fol-
lows:
TABLE 4-1 — Front Panel Controls Initial Set-Up
Control Position To:
LINEAR STBY
METER HV
MODE cw
PLATE Center of band used
LOAD Fully counter-clockwise ‘‘O”
BAND Exciter frequency
CAUTION: Be sure to set the BAND switch to the same
band as that of the exciter before operation is
attempted.
Now you may turn the POWER switch “ON”. Make certain
that the fan motor is revolving. The Multimeter will read
approximately 2 kV on the HV scale. If you turn the
MODE switch to the SSB position the meter will read ap-
proximately 3 kV.
Turn the LINEAR switch to the OPERATE position. The
exciter now controls the TL-922A for automatic transmit/
receive operation. In the CW transmit mode, Ip (plate cur-
rent) in the no signal state should be approximately 100
mA; in the SSB transmit mode, no signal state should be ap-
proximately 200 mA.
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SECTION 4. OPERATION
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4.2 CW OPERATION
CAUTION: Tune-up should be accomplished quickly or
power tube life will be shortened. Maximum
key-down: 10 minutes.
Adjust the exciter for maximum output.
2: Set the amplifier Mode switch to the CW position,
multimeter to RF.
3. Adjust the carrier control on the exciter for a 50 W
level.
4. Set the LINEAR switch on your TL-922A to the
OPERATE position.
5. Increase the carrier control on the exciter for suf-
ficient drive to adjust the tuning.
6. Quickly switch the amplifier to Ip and dip the plate.
7. Switch the amplifier to RF and adjust loading for max-
imum output.
8. Increase exciter output to maximum power (about
100W). Repeat steps 6 and 7 several times for the
highest RF output. If the Ip exceeds 650 mA, reduce
the RF input from the exciter by turning the ALC ADJ
control on the rear panel. Refer to Section 4.5 “’Set-
ting the SLC”.
9. Make certain that the Ig (grid current) is below 200
mA. If not, adjust the ALC ADJ control to reduce
the RF input level.
CAUTION: Never change the BAND switch while trans-
mitting.
TABLE 4-2 —Tune and load initial setting
100W input 502 output loading.
Band Freq. Initial load setting
(MHz) cw SSB
160 1.8 4 2
( 2.0 (5 (35
3.5 3 25
& 4.0 G (3
7.0 3 2
40 C 7.3 Gs G
14.0 45 4
20 14.35 G ( 3.5
21.0 5 45
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4.3, SSB OPERATION
Tune up as in CW operation. Reduce the exciter carrier con-
trol to minimum and change the linear mode to SSB. In-
crease the exciter carrier control and tune for maximum out-
put. When tune up is complete, reduce carrier level to
minimum
a]

( CAUTION: DO NOT key the linear in SSB mode with full
CW power. ALWAYS start and finish this
procedure by reducing exciter carrier level to
minimum
DO NOT, under any circumstance OPERATE your exciter in
the CW mode while the linear is in the SSB mode.
Failure to heed this warning may cause immediate. exten-
sive damage to the amplifier, repair of which will not
be covered by your warranty.
REPEAT: DO NOT OPERATE CW IN THE SSB MODE!
To improve linearity in the SSB mode, adjust the LOAD
control 0.5 to 1.0 division clockwise from the maximum
RF output position and readjust the PLATE tuning control
for maximum reading on the RF scale. This adjustment
should be made only once (not repeated) and will minimize
possible distortion at peak Ip (plate current) allowing your
TL-922A to run at optimum linearity. Note that the Ip (plate
current) should not exceed 400 mA for voice peaks. Even
this low degree of plate current is enough to fully drive the
amplifier. Do not drive the power tubes excessively, turn off
the ALC or otherwise run the Amplifier to distortion. This
will also generate spurious emissions causing interference
with local _stations.] Greatest operating efficiency, cleanest;
signal and extended tube life can be achieved by conserva‘
ive operation.
4.4 RTTY OPERATION
CAUTION: Maximum key down, 10 minutes.
To use a radioteletypewriter (RTTY) with your TL-922A,
follow CW tune-up procedures outlined in Section 4.2.
4.5 SETTING THE ALC ADJ CONTROL
Some exciters may cause the Ip (plate current) in your TL-
922A to exceed 650 mA in the CW mode or the Ig (grid cur-
rent) to exceed 200 mA. If this occurs, remove the cap nut
and adjust the ALC level control on the rear panel to bring
current within specified limits.
If, after following the tune-up procedures outlined in Sec-
tion 4.1, lp and Ig cannot be reduced to their specified
level, proceed as follows:
1, Set the carrier level for 600 to 650 mA maximum Ip
(plate current) and 200 mA or less Ig (grid current).
Adjust plate and load controls for maximum RF
output.
2. Increase the carrier level until Ip (plate current) and
1g (grid current) slightly exceed the specified values
(no more than 750 mA maximum).
3. Set the ALC ADJ control until the Ip (plate current)
is 650 mA or the Ig (grid current) is 200 mA. If
neither reading is affected by this adjustment, re-
setting is unnecessary. High current indicates over-
drive, which results in excessive distortion, spurious
emissions and shortened tube life.
4.6 ADJUSTING THE RF OUTPUT METER
The swing of the RF output reading varies with the im-
pedance of the antenna. To adjust, remove the cap nut and
set the RF METER control on the rear panel to register a 7
division swing when the RF output is maximum on any
selected band.
4.7 HIGH VOLTAGE TRANSFORMER
PROTECTION
The high voltage transformer in your TL-922A has a thermal
protection circuit which operates only if the inside tempera-
ture of the transformer rises over 145°C due to either a full
power, continuous transmission longer than 30 minutes, or
continuous operation in a high ambient temperature en-
vironment. The protection circuit then locks the TL-922A
in the STBY state. The standby relay in your TL-922A can-
not be activated regardless of any switch setting. If protec-
tion has occurred, it has likely been caused by a continuous
run exceeding the rated capacity of the amplifier. Leave the
POWER switch “ON” to allow forced air cooling. While
cooling, the exciter will operate straight through. Protection
lock will be released in approximately 15 minutes. Resume
Amplifier operation with its power lowered appropriately.
4.8 CARRYING YOUR TL-922A
Your TL-922A weighs 31 kg. (68 Ibs.). To carry, use the
handles on the side escutcheons. Do not slide or drop it, as
the plastic legs could be damaged. Do not apply excess
stress to the case. When being transported, repack the unit
in its original shipping container as it was delivered upon
purchase. Whenever your TL-922A is likely to be subjected
to vibrations during transport also remove the power tubes
and repack in their original boxes. See Fig. 7-1 “Packing for
Shipment.”

sau-ctnesaut-agnesttyttt cna ta
5.1
The linear power amplifier in your TL—922A is a grounded
grid class AB, amplifier consisting of two Eimac Hi-mu,
Zero bias triodes, 3-500Z, providing the following features:
5 Low IMD (intermodulation distortion) through nega-
tive RF feedback.
Z. The grounded grid circuit does not require neutraliza-
tion.
3. Due to its low input impedance, no cathode-swamp-
ing resistors are required.
4. High stability at any frequency.
5. Excitation energy is added to the RF output and is
not lost.
Figure 5-1 shows a circuit diagram of the Linear Power
Amplifier. The input matching circuit, comprised of LO
through L14, Cin-1, and Cin-2, matches the exciter im-
pedance with the input circuit impedance to efficiently feed
exciter energy into the power tubes. The tubes are heated
by the center tapped filament transformer T2 requiring
current only half the usual, preventing voltage drop due to
wire resistance.
The choke coils L20 and L3 high frequency isolate the
filaments from the filament transformer. The bias voltage,
which determines the operating point of the tubes, is prod-
uced across zener diode D2. This diode carries the full cur-
rent of the tubes excepting filaments. The grids are DC
grounded through L7 and L8 and high-frequency grounded
by C28 through C33.
The pi network, comprised of VC1, L4, L5 and VC2,
matches the plate impedance to the antenna. The tubes are
cut off to stand by through a positive voltage of approxi-
mately 100 V applied to the filament circuit.
5.2 POWER SUPPLY
The plate high voltage is supplied from a voltage doubling
rectifier comprised of a large-capacity, small-sized trans-
former T1, fourteen high-voltage rectifier diodes rated 800
PIV and eight 200 uF electrolytic capacitors rated 550 V
surge. To improve reliability, the diodes are P.C.B. mounted
and the electrolytic capacitors are held by plastic spacers.
Filament voltage, relay energizing voltage (in common with
the tube cut-off bias voltage), and pilot lamp voltage are
supplied from transformer T2. Each primary of the power
transformers T 1 and T 2 has two windings, each of which is
fused. Note that fuses are not changed when the input
line voltage has been changed (see Fig. 5-2).
5.3. FAN MOTOR DELAY STOP CIRCUIT
The cooling fan is held on for approximately 2 minutes to
cool the power tubes after the POWER switch is turned off.
This is accomplished by the fan motor delay stop circuit
comprised of a bimetal thermal relay.
Figure 5-3 is a schematic diagram illustrating the circuit.
When the POWER switch is at OFF, both the relay RL1 and
the thermal relay DL1 are not activated and the fan is off.
C34 La us ANT
EXCITER
Figure 5-1 — Linear Power Amplifier Circuit
vce
13

120V AC LINE
ISAFUSE SI~1 Ty, Ty
f Yo
10A
)
120V AC
= pat
1SAFUSE S1~2
240V AC LINE
1, T2
0-0
WA
10A |
)
240V AC i
Dp |
Noor
15A FUSE
Figure 5-2 — Transformer Primary Current Flow
NOTE (i): Bridge for 120V Line
METER UNIT (x54—1300—10)
RL 1-1, 1-2
: ; f
|
Y J FROM 100V TAP ON TRANSFORMER 11
AC LINE Figure 5-3 — Fan Motor Delay Stop Circuit
14
By turning the POWER switch to ON, RL1 is activated star-
ting the fan. At the same time, voltage is applied to DL1
generating heat. which makes the contact DL1-1 close in
approximately 60 seconds. By turning the POWER switch
to OFF, RL1 is de-energized, returning contacts RL1-1 and
RL1-2 to their home positions. But, the fan continues
operating
as
the
thermal
relay
contact
DL1-
is
still
closed.
DL1-1 opens after approximately 140 seconds thereby stop-
ping the fan.
54 METER DRIVE CIRCUIT
The power tube Ip (plate current) and Ig (grid current) can be
read on their individual meters. Figure 5-4 is the meter drive
circuit. Ip (plate current) is measured through shunt resistor
R6 (122), and deflects the Ip meter through R7 (1.5 k®) which
adjusts meter sensitivity. Similarly, Ig (grid current) is
measured on the Multimeter. In addition to the Ig, the
Multimeter can selectively read relative RF output (which is
a rectified RF signal), and HV (plate voltage). Precise plate
voltage reading is obtained through three serial voltage
dividing resistors of 5% tolerance.
5.5 SPARK SUPPRESSOR
Your TL-922A contains an oversized relay for conservative
operation and its action is slower than smaller relays. The
TL-922A is momentarily run leaving the antenna circuit
open in such operations as VOX. This leads to high Q at
the output circuit which would cause excessive voltage at
the plate tuning capacitor. This could arc the capacitor.
To prevent this, your TL-922A has a discharge gap device at
the
antenna
relay
terminals
to
dissipate
any
unusually
high
voltage. During relay changeover, you might sometimes
hear arcing from the discharge gap. This is not a failure and
should be considered normal.
R7 1.5kQ
RE 19
o
Ip (PLATE CURRENT
|
PLATE VOLTAGE
SOURCES
le
he ON RF
IG ?
—HV
Ig (GRID [ee
CURRENT)/ ZR5
0.682
d ™
Figure 5-4 — Meter Drive Circuit

WARNING
YOUR TL-922A USES VERY HIGH VOLTAGE. DISCON-
NECT ALL POWER FROM THE TL-922A BEFORE RE-
MOVING OR REPLACING ANY PARTS, PARTICULAR-
LY IN REMOVING THE UPPER AND LOWER COVERS
FOR MAINTENANCE. ALSO MAKE CERTAIN THAT
THE HV METER READS“0"!
6.1 INTERNAL CLEANING
The cooling fan in your TL-922A pulls air in through the
bottom and side walls. Every three months, vacuum clean
the bottom vents, side escutcheon vents, tube glass and
sockets and all areas in which dust collects. Include the
high voltage diodes, the electrolytic capacitors, the vanes
of the plate and load tuning variable capacitors and the fan.
This is necessary to prevent arcing and overheating.
6.2 REPLACING THE POWER FUSES
Power fuses are located at the rear of the TL-922A. In the
nun stacane tts aut atteant atte
SECTION 6. MAINTENANCE
event of blown fuses, first determine the cause. For
replacement, use only 15 A fuses, either in 120V or 240V
line operation.
WARNING
Be sure to disconnect the power cable before replacing
fuses.
6.3 REPLACING THE POWER TUBES
Refer to Section 2.2 “Installation of Power Tubes”
6.4 INPUT MATCHING CIRCUIT
The input matching circuit is preset at the factory for broad
band characteristics and needs no adjustment. There are
dangerous high RF and DC voltages in the circuit. For
readjustment, contact your nearest Trio-Kenwood authoriz-
ed service facility.
15

TROUBLE
‘COMMON CAUSE
REMEDY
1. No power output
1) Relay will not activate.
2) Relay is activated.
b. HV meter will not swing, no Ip
(plate current), cooling fan
inoperative.
c. Ip, RF meter swings off scale,
d. Ip will not change.
a, Exciter RF meter swings off scale.
a. Control cable disconnected.
b. Power supply protector in lock due
to temperature rise from extended
transmi: "
c. LINEAR switch at STBY
D. ALC and RL plugs reversed.
Defective coaxial cable connection.
Interlock switch not depressed due to
faulty upper case cover installation.
Antenna coaxial cable disconnected.
RF INPUT and RF OUTPUT coaxial
connectors reversed.
‘Secure control cable.
Allow standby for approximately 15 minutes
with power switch on for forced air cooling,
Refer to Section 4.7.
Turn switch to OPERATE.
Correct reversed cables.
Correct connection.
Correct upper case cover installation.
Refer to Section 2.2.3.
Correct connection.
Correct reversed cables.
2. Output power too low.
1) Ip (plate current) below 400mA .
2) Hv (plate voltage) in max. drive
state below 1.5kV for CW and below
2kV for SSB.
a. Low exciter output
Improper setting ALC ADJ control
c. Different positions of BAND switches
between exciter and TL-922A.
s
Low line voltage.
Readjust exciter
Readjust control. Refer to Section 4.5.
Set both BAND switches to same position.
Improve line regulation (refer to
Section 2.4).
3. RF meter swing too hi or low
Improper RF control setting.
Adjust RF control until RF meter reads
Approximately 7 on scale. Refer to Section 4.6,
4, Fuse blows when POWER switch is
turned “ON”.
Inside shield plate incorrectly installed
causing interlock switch to short high
voltage line to ground.
Reinstall inside shield plate and replace fuse,
Refer to Section 2.2.2.
5. Upper case over high voltage trans-
former too hot.
Line voltage change terminal cover on
rear removed or ajar.
Replace cover securely.
16

cantante sna seman attain n-nonane AAA a
PACKING FOR SHIPMENT
PACKING MATERIAL
PLASTIC JOINT
PACKING CASE
Figure 7-1 — Packing for Shipment
17

POWER SUPPLY
CAPACITOR:
HOUSING
METER UNIT
(X54-1300-10)
INTERLOCK SW.
(SECONDARY
HIGH VOLTAGE)
INTERLOCK SW.
(PRIMARY HIGH
VOLTAGE)
steht tts amma aE HaHa
INTERNAL PARTS LOCATIONS
tana atm
PC2
c— a
i FAN
PLATE CAPS
Pci
S7
L5
TUBE SOCKET
FUSE, 154
POWER SUPPLY
CAPACITOR
HOUSING
FUSE, 15A
Figure 7-3 — Botoom View

TL.922A
EXCITER, TS-120S, TS-130S, TS-130SE
os + @ fel EOC fal OG)O
—
GROUND
BUSS
RF
OUTPUT
CAUTION: Do not Connect the power cable unless the TL
922A POWER switch is set to the OFF position
TL-922A Interconnection to TS-120S, TS-130S, TS-130SE
EXCITER,
TS-430S
TL-922A
AC LINE
GROUND BUSS RF OUTPUT
CAUTION: Do not Connect the power cable unless the TL.
922A POWER switch is set to the OFF position
TL-922A Interconnection to TS-430S
EXCITER,
TS-930S
TL-922A
‘AC LINE
‘GROUND BUSS
RF OUTPUT
CAUTION: Do not Connect the power cable unless the TL-
922A POWER switch is set to the OFF position
TL-922A Interconnection to TS-930S

EXCITER TS-530S, TS-830S
TL-922A
7
IN
ALC RL
Oees
AC POWER
‘AC LINE
RF OUTPUT
GROUND BUSS.
CAUTION: Do not Connect the power cable unless the TL-
922A POWER switch is set to the OFF position,
TL-922A Interconnection to TS-530S, TS-830S
EXCITER, TS-820 or TS-520S series
TL-922A
ne
RF OUTPUT
GROUND BUSS
CAUTION: Do not Connect the power cable unless the TL-
922A POWER switch is set to the OFF position.
TL-922A Interconnection to TS-520, TS-820 Series
TL-922A
EXCITER, TS-180S
"a
°
a: one
LLL oe
BLACK
=
oc | _
POWER = AC LINE
GROUND BUSS RF OUTPUT
CAUTION: Do not Connect the power cable unless the TL:
922A POWER switch is set to the OFF position
TL-922A Interconnection to TS-180 series