Vco Adjustment - Yaesu FT-991A Technical Supplement

VCO Adjustment

 Connect the Digital DC voltmeter (high-Z) to
TP2002 on the PLL Unit.
 Disconnect the coaxial cable from J2001 on the
PLL Unit, then connect the RF millivoltmeter to
pin 13 of J2001.
 Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
 Referring to the table below, select the ap-
propriate "Alignment menu item" using the
[MULTI] Dial knob per the chart right, and
adjust the listed components for the required
voltage, or confirm that the correct voltage is
present on each alignment menu item.
L2004 L2005
J2001
ALIGNMENT-3
Alignment
Menu Item
01-05 VCO1-HIGH
(TXI)
01-06 VCO1-LOW
01-07 VCO2-HIGH
01-08 VCO2-LOW
01-09 VCO3-HIGH
01-10 VCO3-LOW
01-11 VCO4-HIGH
01-12 VCO4-LOW
01-13 VCO5-HIGH
01-14 VCO5-LOW
 Disconnect the RF millivoltmeter from J2001,
then re-connect the coaxial cable to J2001.
 Press and hold in the [MENU(SETUP)] button
for one second to save the new setting and exit
the alignment mode.
TP2002 L2006 TC2001
FT-99
Alignment
Adjust /
DC voltmeter RF millivoltmeter
Confirm
Adjust
5.1 V ±0.1 V At least 3 dBm
L2004
Confirm
At least 0.3 V At least 3 dBm
Adjust
5.1 V ±0.1 V At least 3 dBm
L2005
Confirm
At least 0.6 V At least 3 dBm
Adjust
4.1 V ±0.1 V At least 3 dBm
L2006
Confirm
At least 0.4 V At least 3 dBm
Adjust
5.0 V ±0.1 V At least 3 dBm
TC2001
Confirm
At least 0.5 V At least 3 dBm
Adjust
5.0 V ±0.1 V At least 3 dBm
TC2002
Confirm
At least 0.8 V At least 3 dBm
TC2002
Technical Supplement
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