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Kessler Engineering TL-922 Revival (tm), Installation Manual

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Kessler Engineering TL-922 Revival (tm) Installation Manual Download Page 15

8

•

8mm Socket

•

5mm Hex Key (Allen Wrench)

•

Soldering Iron and Solder

•

Solder Wick or Solder Sucker

•

Volt-Ohm Meter

•

Heat Gun

CAUTION!

Modification of the TL-922 amplifier requires desoldering

and soldering of numerous components and connections, any of which are
prone to damage if subjected to excessive heat or physical force. Please use
caution.

WARNING!

ALL electrical power must be removed from the amplifier!

No Exceptions! Under no circumstances should the amplifier be plugged into
electrical power, switched

On

, etc., while performing any of these modifica-

tions.

•

Unplug the amplifier from the AC mains supply!

•

Disconnect all other electrical connections to the amplifier.

•

Wait at least 30 minutes after removing AC Mains power before removing any covers
from the amplifier.

•

Remove the amplifier outer and inner top covers.

•

visually inspect (but do not touch) the high-voltage safety switch (shorting strap) and
ensure that it is properly engaged.

www.KesslerEngineeringLLC.com

Summary of Contents for TL-922 Revival (tm)

Page 1: ...TL 922 Revival tm Kenwood TL 922 Linear Amplifier Hardware Upgrade Kit Installation Manual 400 Linden Avenue Suite 2 Dayton Ohio 45403 12 June 2019 Copyright 2012...

Page 2: ...io hobby more enjoyable and trust that our products will bring you many years of faithful service We Thank You for the confidence that you have placed in us and in our products 73 Dr Donald J Kessler...

Page 3: ...4 1 Tools Required 7 3 5 LED Board Installation 9 3 6 Step Start PCB Installation 12 3 7 QSK T R Relay PCB Installation 16 3 7 1 Stock T R Relay Removal 19 3 8 Electronic Bias PCB Installation 24 3 8...

Page 4: ...al Checkout 32 3 8 7 Electrical Schematics 39 4 Service and Warranty 45 Bibliography 45 5 User Notes 47 5 1 User Notes Continued 48 5 2 User Notes Continued 49 5 3 User Notes Continued 50 www KesslerE...

Page 5: ...and Terminal Strip Orientation 14 3 9 Stock Fuse Holder Configuration 14 3 10 Step Start to Fuse Holder Connection 15 3 11 Bias Relay Prior to Removal 16 3 12 After Bias Relay Removal 17 3 13 QSK T R...

Page 6: ...RL CONT to TX connection 31 3 27 Complete Installation of QSK Electronic Bias and Step Start 32 3 28 Electronic Bias ZSAC Adjustment Jumper 36 3 29 Step Start Schematic Diagram 39 3 30 Step Start PCB...

Page 7: ...vii List of Tables 3 1 TL 922 Revival tm Modification Kit Contents 5 www KesslerEngineeringLLC com...

Page 8: ...ineering TL 922 Revival tm Kit may download print and retain personal copies of this manual as required to modify their respective TL 922 RF amplifier while utilizing the Kessler Engineering supplied...

Page 9: ...for a full refund including postage if any of the following apply You are not comfortable working on this amplifier You are not qualified to perform this work You do not fully understand the potentia...

Page 10: ...well as where to find appropriate sources of parts Another complication arises when one attempts to service a modified amplifier particularly if modified by someone else Depending upon the modifier s...

Page 11: ...controlled tube bias 7 Non QSK 8 Meter lamps that are no longer available The most significant problems which require immediate attention are items 1 and 2 the amplifier s tendency to oscillate and it...

Page 12: ...ified TL 922 amplifier The kit comes with all circuit boards assembled and tested Should a fault develop on any of these circuit boards it may be removed and serviced If necessary they may also be ret...

Page 13: ...6 Figure 3 1 TL 922 Revival tm Upgrade Kit Contents www KesslerEngineeringLLC com...

Page 14: ...s well as mechanical layout of the amplifier prior to performing any work on the amplifier Copies of these manuals are available from various sources on the Internet quite often as a cost free downloa...

Page 15: ...ed from the amplifier No Exceptions Under no circumstances should the amplifier be plugged into electrical power switched On etc while performing any of these modifica tions Unplug the amplifier from...

Page 16: ...liding them upward Cut or desolder the lamp wires from the grounding post Remove and discard the Standby and On Air lamps sliding them sideways as necessary Remove but retain the two screws holding th...

Page 17: ...and the meters Inserting this Diffuser will provide uniform illumination of the meters and prevent bright spots Check the orientation of the On Air and Standby LEDs They should point toward their resp...

Page 18: ...11 Figure 3 4 LED Circuit Board Correctly Installed www KesslerEngineeringLLC com...

Page 19: ...tart circuit in series with the AC Mains fuses and the front panel On Off switch Installation Remove the four screws holding the fan enclosure Figure 3 5 Remove the enclosure exposing the mains adjust...

Page 20: ...the 22 twisted pair and its 2 pin receptacle downward near the SO 239 RF Output connector then toward the front of the amplifier Figure 3 7 Inserting Step Start PCB and Routing Wire Leads Re install t...

Page 21: ...mains fuse holders are shown in Figure 3 9 Figure 3 9 Stock Fuse Holder Configuration With the amplifier and fuse area oriented as shown in Figure 3 9 de solder and remove the white 14 wire emerging f...

Page 22: ...from the Step Start PCB to the upper terminal of the right fuse holder Solder together the free end of 14 white wire to the other yellow wire Insulate with Heat Shrink tubing Route the 22 twisted wire...

Page 23: ...nectors as shown in Figure 3 11 Figure 3 11 Bias Relay Prior to Removal Cut the plastic wire ties or string ties in older TL 922 amplifiers holding the grey coaxial cables to the wiring harness Do NOT...

Page 24: ...ust be retained Ensure that the wire running from the filament transformer CT terminal is connected to the filament choke as shown to the far left in Figure 3 12 When finished there should be a small...

Page 25: ...r Orient and place the QSK T R Relay PCB over the chassis opening Fasten securely with two metal screws Solder the exposed leads from the QSK T R Relay PCB to the RF Input and RF Output SO 239 connect...

Page 26: ...gure 3 14 Stock T R Relay Prior to Removal Carefully unsolder and remove the RF choke it will be reinstalled later Remove the two screws holding the T R relay Cut any wires where they connect to the r...

Page 27: ...ve to the amplifier and must be connected to the amplifier s tuned input network Refer to Figure 3 16 on page 21 Solder the shorter coaxial cable s braid to the ground post near the tuned input con ne...

Page 28: ...he RF Choke to the ground post on the side of the amplifier near the output band switch This is the same post that the coaxial cable shield is soldered to Solder the free end of the RF choke to the co...

Page 29: ...22 Figure 3 17 QRO Output to Coax Connection Figure 3 18 RF Choke to Bandswitch Connection www KesslerEngineeringLLC com...

Page 30: ...23 Figure 3 19 QSK PCB to QRO Output Connections www KesslerEngineeringLLC com...

Page 31: ...ns former as shown in Figure 3 20 This area will be used to hold the Electronic Bias PCB Figure 3 20 Zener Bias Diode Prior to Removal Cut the brown wire where it attaches to the Zener diode This is t...

Page 32: ...it However Figure 3 21 does show how the filament supply leads might appear if they were replaced during the filament voltage modification Add a 0 01uF capacitor between the filament transformer C T C...

Page 33: ...he filament trans former Place the rubber grommet as shown it will be compressed and held in place by the Electronic Bias PCB Orient the Electronic Bias PCB and lower onto the filament transformer mou...

Page 34: ...27 Figure 3 23 Electronic Bias PCB Installed www KesslerEngineeringLLC com...

Page 35: ...PTT control RCA jack labeled RL CONT RY QSK Relay PCB already connected GND Chassis ground connection 3 8 4 IG Electrical Connection The brown IG wire will be used to pull the Electronic Bias IG wire...

Page 36: ...Please refer to the orientation of the connecting wires shown in Figure 3 23 as a guide CT Electrical Connection Solder the CT wire lead to the filament transformer CT terminal The CT terminal is the...

Page 37: ...as the bias control circuitry As mentioned previously the label for the 8V winding may be partially obscured by the transformer warning label However the 8V windings are the two terminals shown on the...

Page 38: ...he QSK T R Relays This wire is already soldered to the QSK T R Relay PCB RY terminal GND Electrical Connection Solder the GND lead to the filament transformer E ground terminal The filament transforme...

Page 39: ...tc At this point the amplifier should appear as shown in Figure 3 27 NOTE This Figure shows an additional modification to lower the filament voltage a modification to the grid circuitry as well as mod...

Page 40: ...fier is switched On the AC mains current flow is limited briefly by the two power resistors on the Step Start PCB After a brief interval approximately 2 seconds the Electronic Bias PCB circuitry will...

Page 41: ...on 4 Confirm that neither ON AIR nor STBY lights is illuminated 5 Change the amplifier LINEAR switch from STBY to OPERATE Confirm the STBY light is now illuminated 6 Electrically short the Open end of...

Page 42: ...pen end of the keying line cable Confirm loss of DC continuity between the center pins of the RF INPUT and RF OUTPUT connectors 7 Measure DC resistance between center pin of the RF INPUT connector and...

Page 43: ...he 3 500Z vacuum tubes may be operated upright or upside down However the tubes may not be operated when oriented horizontally The tests may only be performed with the amplifier either upright or upsi...

Page 44: ...the LINEAR switch to STBY 4 While observing the HV meter switch the amplifier ON Confirm Step Start Operation Confirm HV ramps up initially plateau then reaches approximately 2kV after Step Start Rela...

Page 45: ...e approximately 180mA MODE switch to SSB To do so unplug the amplifier from the AC mains Wait approximately 30 minutes for the HV to bleed off then move the bias jumper in the appropriate direction to...

Page 46: ...39 3 8 7 Electrical Schematics Figure 3 29 Step Start Schematic Diagram www KesslerEngineeringLLC com...

Page 47: ...40 Figure 3 30 Step Start PCB www KesslerEngineeringLLC com...

Page 48: ...41 Figure 3 31 QSK T R Relay Schematic Diagram Figure 3 32 QSK T R Relay PCB www KesslerEngineeringLLC com...

Page 49: ...42 Figure 3 33 LED Schematic Diagram Figure 3 34 LED PCB www KesslerEngineeringLLC com...

Page 50: ...43 Figure 3 35 Electronic Bias Schematic Diagram www KesslerEngineeringLLC com...

Page 51: ...44 Figure 3 36 Electronic Bias PCB www KesslerEngineeringLLC com...

Page 52: ...ur service department for return authorization and shipping instructions prior to sending any product for service or repair All items shipped to Kessler Engineer ing must be packed appropriately and i...

Page 53: ...Amplifier Tubes QST pp 36 38 66 89 October 1988 5 Richard L Measures Circuit Improvements for the Heath SB 220 Amplifier Part 1 QST pp 25 29 November 1990 6 Richard L Measures Circuit Improvements fo...

Page 54: ...47 User Notes www KesslerEngineeringLLC com...

Page 55: ...48 5 1 User Notes Continued www KesslerEngineeringLLC com...

Page 56: ...49 5 2 User Notes Continued www KesslerEngineeringLLC com...

Page 57: ...50 5 3 User Notes Continued www KesslerEngineeringLLC com...

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