Yaesu FT-26, Technical Supplement

Page: 18 / 59

Alignment
adjustments may require that more complex ad­
justments be performed afterwards. Do not at­
tempt to perform only a single step unless it is
clearly isolated electrically from all other steps.
Rather,have all test equipment ready before begin­
ning, and follow all steps in a section in the order
presented.
Required Test Equipment
D
RF Signal Generator with calibrated output
level at 200 MHz
D
Deviation Meter (linear detector, with 300 Hz -
3 kHz BPF)
D
Oscilloscope
D
AF Millivoltmeter
0
SINAD Meter
D
Inline Wattmeter with 5% accuracy at 200 MHz
D
Regulated DC Power Supply adjustable from 5
to 13V, 2A, with Ammeter (0 to 2000 mA)
D
50-Q Dummy Load: lOW at 200 MHz
D
Freq. Counter:± 0.2 ppm accuracy at 200 MHz
D
AF Signal Generator with calibrated output
D OC
Voltmeter: high impedance
D
Spectrum Analyzer
D
VHF Sampling Coupler
Alignment Preparation
&
Precautions
A 50-Q dummy load and inline wattmeter must
be connected to the main antenna jack in all proce­
dures that call for transmission, except where spe­
cified otherwise. Correct alignment is not possible
with an antenna.
After completing one step, read the following
step to determine whether the same test equip­
ment will be required. If not, remove the test
equipment (except dummy load and wattmeter, if
connected) before proceeding.
Correct alignment requires that the transceiver
and test equipment be at the same temperature as
the surrounding air, which should be held constant
between 20 and 30 °C (68- 86
°F).
When the trans­
ceiver is brought into the shop from hot or cold air
it should be allowed some time for thermal equali­
zation with the environment before alignment.
Alignments must only be made with oscillator
shields and circuit boards firmly affixed in place.
Also, the test equipment must be thoroughly
warmed up before beginning.
Note: Signal levels in dB referred to in the align­
ment procedure are based on 0 dBµ= 0.5 dBµV.
PLL
&
Transmitter
Set up the test equipment as shown here for
transmitter alignment. Maintain the supply vol­
tage at 12.0V for all steps.
PLL &
Transmitter Alignment Setup
50-ohm
Dummy Load
Freq. Counter
Spectrum
Analizer
lnline
Wattmeter
Deviation
Meter
AF
Millivoltmeter
AF
GENERATOR
AF
Millivoltmeter
Regulated
12V PSU
PLL VCV (Varactor Control Voltage)
D
Connect the positive lead of the DC voltmeter
to the test point TP6001 on the PLL Unit, and the
negative lead to chassis ground.
D
Tune the transceiver to 144.000 MHz, key the
transmitter, and adjust transformer T6001 on
the VCO Unit for 0.7 ± 0.05V on the voltmeter.
D
Return to receive, and adjust T6002 for 1.1 ±
0.05V on the meter.
D
Retune to the frequency indicated below for the
version being aligned, and confirm the indi­
cated receive and transmit VCV on the meter.
Version Frequency TxVCV RxVCV
A1 & 82 148 MHz <1.2V
<1.8V
81
146 MHz <1V <1.5V
Transmitter Output Power
D
Tune to the center of the band (145 or 146 MHz),
and select the high power output setting (press
FIM
�
H/L,
and then
H/L
again, if necessary).
D
Key the transmitter and adjust VR1002 on the
Mother Board for peak on the wattmeter (at
least 5.5W with less than 1.7 A supply current).
D
Press
FIM
�
H/L
again and select each of the low
settings, confirming the output and display in­
dicated below.
Low
RF Output
Bargraph
Selection Segments
L1
0.3-1W 3
L2 1.3-2W 6
2.5-3.5W
D
Select the
L
1
low power setting, and transmit at
the low and high band edges to confirm trans­
mitter output between 0.2 and lW.
FT-26 Technical Supplement