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World of Ham Radio 1997
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1997-02-01
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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 # 866
MODEL: TS-930S
SUBJECT: Hetrodyne Tone
Some users of the TS-930S have reported that a heterodyne is heard when
the VBT control is tuned in the CW mode. The tone may be more noticeable
with no signal presentt (e.g. no antenna connected.), or when the AF
tune or CW PITCH controls are tuned. This may be reduced or eliminated
by the following procedures.
PARTS REQUIRED
QTY DESCRIPTION KENWOOD PART NUMBER
1 Shield Kit Z930CARSHIELD
1 Cover CAR F11-0813-04
1 Shield CAP F10-1380-04
1 8.2K 1/4 watt Resistor
1 22K 1/4 Watt Resistor
1 3pf disc capacitor
1 0.5pf disc capacitor
1 1.0pf disc capacitor
PROCEDURE
1. Remove the top and bottom covers from the TS-930S.
2. Turn the radio bottom up to allow access to the Signal Unit (X57-1000-11).
3. Remove the twenty-two (22) screws that secure the Signal Unit/Heat
sink to the chassis. Unplug the RAT, DRV, XVT, FRO, and the VCOF
coaxial cables from the Signal Unit. These are located along the rear
and the left side of the Signal Unit. Unplug connectors number (16)
and (20) located along the right of the Signal Unit.
4. Gently lift up on the rear of the Signal Unit and fold the board over
towards the front panel to allow access to the bottom of the board.
5. Install the shield plate on the botton of the board. Cut the circuit
foil and add the jumper wire as shown.
6. Change the following components:
Change R635 to 8.2K
Change R501 to 22K
Change C469 to 3pf
Change C473 to .5pf
Change C476 to 1pf
7. Reinstall the signal unit. Pay carefull attention to the coaxial
connectors when reinstalling to ensure they are in the correct locations.
8. Install the top cover to CAR 1 enclosure to complete the Signal Unit
modification.
9. Turn the set over so top is up. Remove the four (4) screws that secure
the speaker assembly to the chassis and lift up gently (unplug the
battery backup connector). The assembly may then be folded over to
the right with cables attached. Remove the four (4) screws that secure
the Digital assembly to the chassis and fold the assembly up and
towards the front panel, to allow access to the PLL Unit.
10. Remove resistor R73 and capacitor C99 from the PLL Unit.
11. Reverse the procedure in step 9 to reinstall the Digital and Speaker Units.
ADJUSTMENTS
1. Connect an oscilloscope probe to the CAR 1 terminal (24) of the Signal Unit.
Adjust L161 for 300mv p-p signal amplitude.
2. Connect the oscilloscope probe to the emitter of Q79. Adjust L142, L144,
and L145 for maximum signal amplitude, then adjust L139 for lv p-p
amplitude.
*NOTE: NOTE THE USB FREQUENCY BEFORE ADJUSTING L139.
3. Adjust TC4, TC5, and TC6. (Refer to Service Manual)
4. Adjust TC3 so the frequency is again the same as measured in Step 2.
4. Replace top and bottom covers to complete the modification.
Time required for this modification is 1 hour.