Yaesu FT-757GX II, Техническое дополнение

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N. PLL Subloop (PLL-1) VCC
1. Connect the hi-Z DC voltmeter to TP 2003 and
tune the transceiver for 14.499 .00 on the
display. Adjust T 2008 for 5 .5 V on the meter.
2. Retune the transceiver for a display of
1 4.500.00, and check for 2 to 3 volts on the
meter.
0.
41 and 56 MHz Bandpass Filters
1. Connect the RF voltmeter to TP2004 and
tune the transceiver for 14.250.00 on the
display. Adjust T2014 through T2017 for
maximum deflection on the voltmeter (more
than 60 mVrms).
2. Retune the transceiver to 21.250 MHz, and
adjust T 2018 through T 2021 for maximum
deflection on the voltmeter (more than 60
mVrms).
P. Main PLL (PLL-2) VCC
1 . Connect the hi-Z DC voltmeter to TP2005 and
tune the transceiver to the frequencies shown
in the following chart, adjusting the cor­
responding transformer for 1 .5 V on the
meter. Then retune the transceiver to the
corresponding "check" frequency, and check
for 5 to 6 V on the meter.
ADJUSTMENT (for l .5V)
CHECK (for 5-6V)
Freq. (MHz) Transformer
Freq. (MHz)
0.500
T 2023 7.499
7.500 T2024 14.499
1 4.500 T202s
21.499
21.500 T 2026 29.999
2. Check for proper VCC control by tuning
between the adjustment and check frequencies
in each of the above four ranges, using the
tuning knob or microphone scanning buttons,
and watching the DC voltmeter for smooth
voltage change. If the voltage changes un­
evenly, or jumps, a fault is indicated.
Q. 2nd Local Level
Connect the RF voltmeter to J 2009. Adjust T 2003
through T 2005 for maximum RF voltage on the
meter (atleast 1 1 0 mVrms).
R. IF Shift Zero Point Set
1. Connect the frequency counter to J 2009, and
with the Shift and Width controls centered,
note the counter frequency while receiving.
Then key the transmitter and adjust VR2007,
if necessary, so that the frequency shown on
the counter is within 50 Hz of that shown
while receiving.
2. While receiving, check the total adjustment
range of the Shift control in USB, LSB and
CW, which should be approximately ±1.3 kHz
as shown on the counter. If not, adjust L2011
(not more than 90° in either direction), and
then repeat adjustments H, I and J (Carrier
Point, BFO Frequency and FM/ AM Carrier
Frequency), and then this check again.
S. VOX Gain Preset
1. Preset VR2011 fully clockwise, and set the
VOX GAIN control on the rear panel fully
clockwise. Connect the AF signal generator
to the PATCH jack, and apply a 1 kHz signal
at 1 m V to check to see if the transmitter
activates.
2. Now rotate the VOX GAIN control fully
counterclockwise, and slowly adjust VR2011
counterclockwise to the point where the
transceiver returns to receive, and then a little
further counterclockwise from this point.
T. SSB Carrier Point Check
1. With the AF generator connected as in the
previous step, set the transceiver to the
14 MHz band, USB mode. Close the PTT line
and adjust the MIC gain control for 100 watts
output (into the dummy load/wattmeter).
For the 10-watt model FT-757SX, divide all
power outputs by l 0.
2. Reduce the frequency of the audio generator
while watching the wattmeter, to obtain 25
watts output. Check that the audio frequency
is below 350 Hz.
3. Now increase the frequency of the AF
generator so that the power output rises to
full power and then down to 25 watts again
above 2 kHz. Check that the audio frequency
is now above 2900 Hz.
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