Yaesu FT-901DM Instruction Manual page 46
Hide thumbs
Also See for FT-901DM:
- Maintenance service manual (199 pages) ,
- Instruction manual (54 pages) ,
- Survival manual (37 pages)
Table of Contents
Advertisement
1 1 . KEYER ADJU STMENT
V R2 7 0 2 con trols the d ot-to-sp ace ratio for the
built-in electronic keyer ; this is normally set to
1 : 1 at the factory. VR2 7 0 1 adj u sts the symme try
b e tween dots and d ashes. Once VR2 7 0 1 i s set,
this se tting is correct for all keying speeds. Ad
justment of V R2 7 0 2 will make b o th d ots and
dashes change uniformly with respect to the
sp ace . Both of these controls are l ocated on
PB- 1 7 2 8 .
V R2702
Q2101
K e y e r u n i t
1 2 . CLARIFIER ADJUSTMENT
With the transceiver in the receive mode, p ush
the RX CLARI FIER bu tton and set the CLARI
FIER control to 0. Tune in the marker signal on
any b and and then switch the RX CLARI FIER
button OFF. I f the frequency changes at all ,
adjust potentiome ter VR2 1 0 1 , which is located
inside the cabin e t near the CLARIFIER con trol
p otentiome ter.
MJ 1 2
( V CO u n i t )
T u n e board
( PB - 1 720)
1 3 . VOLTAGE REGULATOR ADJUSTMENT
Connect a VTVM DC prob e b e tween pin 1 0 of
MJ 1
(PB- 1 7 1 7 )
and ground.
p o te ntiome ter V R 1 8 0 1
indicated on the VTVM .
VR21 0 1
( PB - 1 7 2 8 )
V R 2 1 0 1 Band s w i t c h
Adjust 6V S ET
for e x actly 6 Volts as
R e ctifi er
1 4 . BIAS ADJUSTMENT
The final amplifier bias mu st be checked to ensure
linearity and normal operating plate dissipation
for the final amplifier tubes. Adj u st the B I AS
control VR 1 0 0 1 on PB- 1 7 08 a s follows : set the
transceiver in the receive mode and allow the
tubes to reach n ormal operating temperature .
Set the MODE switch to U S B , the M ETER swi tch
to IC, and the VOX GAIN control to MOX , so
as t o activate the transmitter. The me ter will
then in dicate cathode current for the PA tubes.
The idling cathode curren t is 50 m A if the b ias
is correct (25 mA for the SD m o d el) . If the idling
cath ode current is o ther than 50 mA, adjust the
BIAS c on trol VR 1 0 0 1 for the correct value.
V R 1001
R e c tifi e r
4 4
-
-
C
( P B - 1 7 1 7 )
u n i t
A
( P B - 1 708 )
u n i t
V R 1so 1
Q 1 so 1
Q 1 804
Q 1 806
Advertisement
Table of Contents
