HAM Radio 3/hamradioversion3.0examsandprograms1992.iso/kenwood/ken_mods/ts940.12

Text File | 1990-08-26 | 2KB | 37 lines

TS940.12

The quickest way to verify whether the fix has been installed
is to check R120 and R129 on the PLL Unit (X50-2020-00).  If
these two resistors are 3.3 ohms in value, the fix is already
installed.  Do not depend on the on the absence of C176, C180
or C181 as an indication, as earlier attempts (factory or
field) to correct the mixing noise problem may have removed
these same capacitors.  The instructions in the bulletin
state that when making the modifications to the RF Unit (X44-
1660-00), it is easiest to move C132/C133 to the foil side of
the board.  As the component side of the section of the RF
Unit containing these two capacitors has been filled with
wax, it is definitely not easier.  The factory installation
of the fix left C132/C133 on the component side and
insatalled the R154/C193 and R155/C194 series RC networks on
the foil side.  This is definitely easier.  As a side note,
the instalation of the fix took me about 2 hours.  Both the
PLL Unit and RF Unit modifications must be completed before
the transceiver is usable.  If you install just the PLL Unit
modifications and then try the receiver, CW signals will
sould like raw AC.  Also, to make life simple, do not remove
each of the boards above the PLL Unit individually.  The easy
way to gain access to the PLL Unit is to remove the top two
screws (one on each side) holding the front panel and loosen
the bottom tow screws.  This allows the front panel to be
tilted forqard.  The speaker assembly and all the boards
above the PLL unit may then be removed as a unit by removing
only 4 screws and tilting this unit towards the front of the
TS-940S.  No cables need be removed from the boards above the
PLL Unit.
I hope the above information is helpful to you in dealing
with the reciprocal mixing noise problem.  (Thanks, Rich
Maher, WZ4Z, 1117 NW 7th St., Boynton Beach, FL 33435)
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