Tune to:
Adjust:
for indicated
of:
30.000.0
MHz
L2027
8.0 V±0.1 V
21.500.0
MHz
confirm
1.0
- 2.0 V
21.499.9
MHz
L2019
8.0V+0.1V
14.500.0
MHz
confirm
1.0 - 2.0 V
14.499.9
MHz
L2017
8.0V+0.1V
7.500.0
MHz
confirm
1.0 - 2.0 V
7.499.9
MHz
L2011
8.0
v
+ 0.1
v
0.100.0
MHz
confirm
1.0 - 2.0 V
Table
1.
VCO Voltage Alignment
Receiver Circuits
Refer to the Main Unit Alignment Diagram
on page
3-8
for location of components.
IF
Interstage Transformers (I)
(coarse alignment - Rx Carrier Balance)
D Connect the
RF
signal generator to the
ANT
jack, and an
AF
millivoltmeter with speaker to
the
EXT SP
jack.
0
Set VR1003
& IF SHIFT
to 12 o'clock position,
them set VR1002, VR1004 and VR1007
fully cw. Inject a+ 100 dBµ signal at 14.200.0
MHz, then adjust T1001-T1008
&
T101 O-T1012 in sucession several times for
peak indication on the millivoltmeter.
D Reduce the SG output level for an S-meter
indication of S-3 - S-5, then adjust VR1006
for peak
AF
output or max. S-meter indication.
IF
Interstage Alignment
D Inject a +80 dBµ signal at 14.200.0 MHz.
Connect the AF millivoltmeter across an 4-8-
n
load to the
EXT SP
jack on the rear panel.
D Preset VR 1004 fully clockwise, and adjust
T1001 - T1008 and T1010 - T1012 in suc
cession several times for peak AF output or
S-meter indication (adjust SG level as neces
sary to keep meter approximately mid-scale).
1st Mixer Balance
D Preset VR1003 fully clockwise, then, in LSB
mode, tune to the internal heterodyne around
15.310 MHz, and adjust VR1003 alternately
several times for a null in AF output.
FT-840 Technical Supplement
Alignment
S-Meter Full Scale
D Inject a+ 100 dBµ signal at 14.200.0 MHz, next
adjust VR 1002 on the Main Unit so the meter
deflects to the
59 +60 dB
marker on the S-meter
scale.
IF Gain
D Inject a +8 dBµ signal at 14.200.0 MHz to the
antenna jack and adjust VR1004 for an S-1
meter deflection.
Squelch T hreshold
NB
D In the USB mode, with no signal at the antenna
jack, set the
SOL
control to the 10-o'clock
position, and adjust VR1005 so that the
squelch just closes.
D Inject a +20 dBµ signal at 14.200.0 MHz, then
connect a DC voltmeter to TP1001.
D Press the
NB
button, then adjust T1022 and
T1023 alternately several time for minimum
indication on the voltmeter.
Transmitter
Connect the
50-Q
dummy load to the an
tenna jack for all procedures. Refer to the Main
Unit Alignment Diagram on page
3-8
for loca
tion of components.
PA Unit Idling Current
D Adjust the
RF PWR
and
MIC
controls fully ccw
(min.).
D Connect a DC Ammeter to TP5001 (-) and
TP5002( + ), and select USB mode.
D Key the transceiver and adjust VR5001 for 400
mA ± 50 mA.
ALC Meter Zero Set
D Select the ALC meter function, then preset the
RF PWR
control fully cw (max.), and the
MIC
&
VR1010 controls fully ccw (min).
D Select USB mode, key the transmitter, and with
no modulation, adjust VR1013 to the point
where the ALC meter just begins to deflect.
3-3
Содержание FT-840
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