home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
World of Ham Radio 1997
/
WOHR97_AmSoft_(1997-02-01).iso
/
mods
/
kenwood
/
asb_text
/
asb0937.txt
< prev
next >
Wrap
Text File
|
1997-02-01
|
3KB
|
70 lines
==============================================================================
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 # 937
MODEL: TM-721A
SUBJECT: AF PA WHITE NOISE WITH SQUELCH ON
Some users of the TM-721A may detect white noise from the speaker with
the squelch turned on. The noise can be reduced by lowering the gain of
the Audio Frequency Power Amplifier. To compensate for the reduction,
the gain of the pre-amplifiers will be increased. In addition, the beep
level will be raised.
REQUIRED PARTS
12K OHM 1/10 WATT CHIP RESISTOR RK73FB2A123J
18K OHM 1/10 WATT CHIP RESISTOR RK73FB2A183J
1. Disconnect the power supply and antenna from the transceiver.
2. Remove the top and bottom covers (12 screws). Do not damage the
speaker wires when removing the top cover.
3. Unplug all connectors from the TX-RX (VHF) unit on the top of the
transceiver. Remove the 7 screws from the board and then pull the
board from the transceiver
4. Unplug all connectors from the TX-RX (UHF) unit on the bottom of the
transceiver. Remove the 6 screws from the board and then pull the board
from the transceiver.
5. Remove the silver colored screws from the front panel chassis (2 on
each side, 1 on top, and 1 on the bottom).
6. Pull the front panel assembly away from the body of the transceiver
(do not disconnect any cables).
7. Remove the 6 screws from the Control unit (A/3) which is mounted on
the body of the transceiver.
8. Pull the board away from the transceiver, but do not disconnect the
red and black wires. Keep track of the two short coax cables that
run under the Control unit. The cables connect between both TX-RX units.
9. On the component side of the Control board (the side with the
majority of connectors) replace R7 with an 18K ohm chip resistor
10. Assemble the front panel by reversing steps 5 - 8. Do not forget to
run the two short coax cables (mentioned in step 8) under the
Control Unit.
11. On the foil side of the TX-RX (UHF) unit, remove chip resistors R37
and R41.
12. On the foil side of the TX-RX (VHF) unit, replace R43 with a
12 K ohm chip resistor.
13. Assemble the transceiver by reversing steps 1 - 4.