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World of Ham Radio 1997
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==============================================================================
K E N W O O D
>>> A M A T E U R R A D I O S E R V I C E B U L L E T I N <<<
==============================================================================
Kenwood Service Centers
Kenwood Service Corporation Kenwood Service Center, East
2201 East Dominguez Street 829 Lynnhaven Parkway, Suite 130
Long Beach, California 90801 Virginia Beach, Virginia 23452
Telephone 1-310-639-5300 Telephone 1-804-340-1702
==============================================================================
BULLETIN # 946
MODEL: TH-215A/TH-415A
SUBJECT: TX SIGNAL-TO-NOISE RATIO IMPROVEMENTS
The TH-215/415 transmit signal-to-noise ratio is typically 30 dB. This
ratio is more than sufficient for routine operations. For those users
who would like to obtain additional performance, the following modification
will provide an improvement of 5 to 8 dB.
REQUIRED PARTS:
47 OHM 1/10 WATT CHIP RESISTOR RK73FB2A470J
220 OHM 1/10 WATT CARBON RESISTOR RD14BB2B221J
22uF 6.3V ELECTROLYTIC CAPACITOR CE04CW0J220M
1uF 50V ELECTROLYTIC CAPACITOR C90-1248-05
1. Disconnect the battery and antenna.
2. Remove the 7 screws from the back panel of the transceiver
3. Lift the front panel from the transceiver and lay it to the right side.
4. Disconnect the 2 flex cables and remove the 3 screws from the IF unit
5. Pull the top panel off and then remove the IF unit.
6. Remove the 8 screws from the RF unit and unplug connector CN2
Remove the RF unit from the back cover.
7. Locate R50 (TH-215) or R60 (TH-415) on the foil side of the RF unit
Replace the resistor with a 47 ohm chip resistor.
8. On the component side of the IF unit, add a 1uF capacitor as shown in
figure 5.
9. Also on the component side, cut one foil, add a 220 ohm resistor, and
add a 22uF capacitor as shown in figure 6.
10.Assemble the transceiver by reversing steps 1 - 6.
Time required for this modification is 1.0 hrs or less.