Yaesu ft 757 gx owners manual

Page 2

SERVICE AND ALIGNMENT

The FT-757GX is carefully designed to allow the
knowledgeable operator to make all adjustments
required for various station conditions, modes and
operator preferences simply from the controls on
the front and rear panels, without opening the case
of the transceiver. These adjustments are described
in the FT-7S7GX Operating Manual.

The following procedures cover the sometimes
critical and tedious adjustments that are not
normally required once the transceiver has left the
factory. We recommend that these adjustments be
made only by authorized Yaesu service representa-
tives, as many are interdependent and difficult to
perform correctly without prior experience with
FT-757GX alignment. Without such experience
and the proper test equipment, any attempt to
make internal adjustments is likely to cause
degraded transceiver performance, the correction
of which is not covered by the warranty policy
when caused by unauthorized internal adjustments.

In the unlikely event that a sudden failure occurs
during normal operation, do not attempt realign-
ment. Such failures are almost always due to the
failure of a component, often in an external
accessory, or a problem with the antenna system.
Once the external connections have all been
checked, if the transceiver is still suspect, the
Yaesu representative through whom the transceiver
was originally purchased should be contacted
immediately for instructions regarding repair.
Authorized Yaesu service technicians automatically
perform complete performance cheeks and realign-
ment of all circuits that may be affected once a
faulty component has been replaced.

Those who do undertake any of the following
alignments are cautioned to proceed only at their
own risk. Yaesu must reserve the right to change
circuits and alignment procedures in the interest of
improved performance, without notifying owners.
Under no circumstances should any realignment
be attempted unless the normal function and
operation of the transceiver are clearly understood,
the malfunction has been carefully analyzed and
any faulty components replaced, and the need for
a specific realignment determined to be absolutely
necessary. Procedures not involving adjustments
are termed checks, and are included for trouble-
shooting purposes.

The following test equipment (and thorough
familiarity with its use) is required for complete
alignment. While most steps do not require all of
the equipment listed, the interactions of such
adjustments may require that more complex
adjustments be performed afterwards. Do not
attempt to perform only a single step unless it is
clearly isolated electrically from all other steps.
Rather, have all test equipment ready before
beginning, and follow all of the steps in the order
that they are given in each section.

During all of the following procedures that call for
the transmitter to be activated, a SOphm dummy
load must be connected to the antenna jack,
except where specifically stated otherwise.

Also, the WIDTH/SHIFT controls must be set to
the 12 oclock position, the RF gain control must
be fully clockwise, and the SQL control must be
fully counterclockwise, unless stated otherwise.

After completing one step, read the following step
to determine whether the same test equipment will
be required. If not, remove the test equipment

(except dummy load and wattmeter) before
proceeding.

UNIT

UNlT

FT-757SX (10 W)
Underside of Heatsink

KEYER

KEYER
CONTROL