Yaesu FT-902DM Instruction Manual page 47

2. VOX ADJUSTMENT
Tune in a sign al and adjust the AF GAIN con trol
for a n ormal listening leve l . With the microph one
positioned n e ar the speaker, increase the VOX
GAIN control on the front p anel un til the speaker
output causes the VOX relay to switch t o the
transmit m o d e . Set the ANTITR IP c on trol V R 6 0 1
on P B- 1 84 6 t o the point that will just prevent the
.
speaker output f r om tripping the VOX relay .
Speak into the m i croph on e in a norm al voice to
see i f one ' s voice will activat. e the VOX relay . If
not, VR 6 0 1 may b e advanced too far.
Adjust the D E LA Y con trol V R 6 0 2 for the desired
release d el a y . Cl ockwise rotation of V R 6 0 2 will
in crease the d e l ay tim e . For CW semi-break-in
operation , V R 6 0 2 shoul d likewise be adjusted to
suit the o p e rator's preferences. For CW operation
with a foo t switch for relay actuati on , the VOX
GAI N control may b e rotated ful l y coun ter­
clockwise ( b u t n o t to the click-stop . which is the
MOX p osition ) to disable the VOX syste m .
3 . CW SIDETONE LEVEL
Adj u stment of the CW sidetone level may be
made by a djustment of p otentiome ter V R 6 0 3 ,
located on PB- 1 84 6 , while the transceiver is being
keyed .
Q515
Q513
Q512
Q 514
Q5oa
V O X /M a r ke r P B - 1 8 4 6
u n i t
CARRIER B A LANCE
4 .
The transceiver should be allowed to reach n orm al
operating temperature
b alance adj ustmen ts.
Tune u p the transceiver for SSB operation u sing a
b e fore making carrier
m atched an tenna or dummy load . Turn the M I C
G A I N control fully counterclockwise to rem ove
all audi o input f r om the modulator stage .
With the M O D E swi tch se t to either LSB or U S B ,
turn the VOX GAIN control t o MOX an d adjust
the carrier b alance con trol s V R 7 0 1 and TC 7 0 5
a
on P B- 1 7 06A for
th e METER swi tch in the PO position .
A m ore p recise b alance may b e ob tained b y tuning
a receiver which has an S meter to the transmitted
f r equency . Adjust VR 7 0 1 and TC 7 0 5 for a mini­
mum S me ter re ading on the remote receiver
while switching the MODE swi tch back an d forth
between the two SSB p ositions ; this will help
ensure good carrier suppression on b o th LSB and
·
U S B .
5 . AMGC ( Au toma tic Mic Gain Control )
The hold time of the AMGC system is adjusted
by V R 7 0 2 on PB- l 7 06 A ; clockwise rotation of
\LR7 0 2 will p rovide a l onger h old tim e .
6 . CARRIER F REQ UENCY ADJU STMENT
Tun e up the transmitter on 20 me ters in the U S B
a
m od e , using dummy l o a d . Apply a 1 kHz audi o
signal to the mi crophone input and adjust the
audio generator output for 30 watts outp u t from
the transmi tter as me asured by the dummy load
wattme ter. Shift
frequency t o 3 00 H z without changing its outpu t
leve l . Adjust TC 7 0 1 un til the power ou tpu t be­
comes 8 watts. Repeat this procedure for the
LSB mode .
NOTE :
Recheck the carrier b alance a fter ad­
ju sting the carrier f r equency.
Connect a frequency c ounter to pin 1 7 o f the
N B UNIT PB- 1 9 9 4 . Transmi t in the AM mod e .
S e t TC 7 0 3 for a reading o f 8 9 8 8 . 2 9 5 k Hz on the
fre quency counter.
Tran smi t on the F S K mode. Set TC 7 0 4 a re ading
of 8 9 8 8 . 1 2 5 kHz on the frequency cou n ter. Re­
peat this procedure for AM an d then FSK until
b o th frequencies are . indicated correctly on the
coun ter. Ground the inner conductor o f the F S K
j ack on the rear p anel a n d confirm that t h e fre­
quency shifts to 8 9 8 8 . 29 5 kHz.
- 4 5-
minimum me ter readi n g with
the audio generator outpu t