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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 # 1004
MODEL: TS-450S
SUBJECT: TX Frequency Response
We have received several reports concerning the transmit audio quality of
this unit. Several reporters noted that the signal sounded "hard" or had a
reduced bandwidth, while others noted a difference in the noise quality when
switching between USB and LSB. We noticed a significant difference between
the output power in LSB and USB on some of these sets.
Cause:
Improper adjustment of the 8.83 MHz tuning coils (L73, L76) on the RF Unit
(X44-3130-00) can cause these symptoms. The coils have two tuning points.
One is reached when the tuning slug projects above the surface of the coil
form. When tuned in this manner the bandwidth becomes narrower than normal
and causes the symptoms noted above.
Alignment Procedure:
1. Adjustment should be performed with the YK8-88S1 (2.4kHz) filter in
line. If this filter is not present you should select the THRU position
for the 8.83 MHz IF.
2. Adjust L73 and L76 according to the instructions provided in the service
manual (Item 6 of the Receiver adjustment). Ensure that the slugs are
preset well down in the coil form, then adjust for peak. You should
reach this point before the top of the slug exits the coil form.
3. Next, re-adjust L74 and L75 (Item 8 of the Receiver adjustment.)
a. Select the 6 kHz filter for both the 8.83 MHz IF and the 455 kHz IF.
b. Select a dial frequency of 14.100.4 MHz.
c. Select the USB mode.
d. Adjust L74 and L75 for maximum.
e. Select the LSB mode.
f. Readjust L74 and L75 for maximum.
g. Repeat steps [3c] through [3f] several times until you obtain a
difference of 2 dB or less in the AF output when switching between
USB and LSB.
4. Check Item 14, CAR point adjustment (Transmitter section) Menu items 11
and 12, and confirm that the transmitter power is equal for USB and LSB.
Time required for this modification is 30 minutes or less.