Yaesu FT-902DM, Instruction Manual

Page: 49 / 55

1 1 . KEYER ADJ USTMENT
V R2 7 0 2 con trols the d ot-to-space ratio for the
built-in electronic keyer ; this is normally set to
1 :
1
at the factory . VR2 7 0 1 adjusts the symme try
between d o ts and d ashes. Once VR2 7 0 1 is set,
this se tting is correct for all keying speeds. Ad­
justment of VR 2 7 0 2 will make b o th d ots and
d ashes c hange uniformly with respect to the
space. Both of these controls are l ocated on
PB- l 7 2 8 A.
V R 2102
Keyer unit
(PB- 1 728A)
1 2. C LA RIFIER ADJ USTMENT
With the transceiver in the receive mode, push
the RX C LARIFIER button and set the CLARI­
FIER control to 0. Tune in the marker signal on
any band and then switch the RX CLARI FIER
button O F F . If the frequency changes at all ,
adjust p o te n tiometer VR2 1 0 1 , which is l ocated
inside the cabinet near the CLARI FIER control
po ten tiome ter.
M.J 1 2
( V CO un i t )
Tune b o a rd
( P B - 1 7 2 0 )
V R 2 1 0 1 B a n d swi t c h
1 3 . VOLTAGE REGU LATO R ADJUSTMENT
Connect a VTVM DC probe between pin 1 0 o f
MJ 1 (PB- 1 7 1 7
A)
a n d ground. Adjust 6V S ET
p otentiome ter V R 1 8 0 1 for exactly 6 Volts as
indicated on the VTVM .
Rectifier C u n i t
(PB-.1 7 1 ?A )
1 4 . BIAS ADJ USTMENT
Q 1 s o 1
The fin al amplifier bias mu st be checked to ensure
linearity and normal operating plate dissipation
for the final amplifier tubes. Adjust the BIAS
control VR 1 0 0 1 on PB- 1 7 08A as foll ows : set the
transceiver in the receive mode and allow the
tubes to reach n ormal operating tempe rature.
Set the MODE switch to USB , the M ET E R swi tch
to IC, and the VOX GAIN control to MOX, so
as to activate the transmitter. The me ter will
then in dicate cathode current for the PA tubes.
The idling cathode curren t is 50 mA if the bias
is correct ( 2 5 mA for the SD model). If the idling
cathode current is other than 50 mA, adjust the
BIAS c on trol YR 1 0 0 1 for the correct value .
V t-< 1 0 0 1
Rectifi e r
A
un i t
(PB- 1 708)
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