Yaesu FT-901DM Instruction Manual page 49

ADVICE ON TROUBLESHOOTING
THE DRIVER/FINAL ST AGES
Three tubes are used in the FT-90 1 DM : a 1 2B Y 7 A
and t w o 6 l 4 6 B 's , run in parallel i n the final .
B e cause not all service personnel are as familiar
with t ubes as they are with semiconductors , we
would begin by cautioning you that tubes are
v oltage devices. To produce power in useful
amoun t s , they require voltages well in excess of
t hat needed for solid state d evices . Take care , lest
y ou q uickl y develop
m alady well kno wn to old timers . It occurs when
y our arm j e rks back from the +800 volts right into
s ome immovable o bj e c t . Accompanied by a few
c o lorful p hrases , i t is n o t an experience one
knowingly e n courages , though it is seldom fatal .
should
I f you come into contact with the high
voltage , it is best to take a break from servicing.
Alert y our colleagues t o what happene d , and seek
m edical attention should
( t rauma) d evelop . Trauma following contact with
h igh voltage i s sometimes more dangerous than the
h igh voltage i tself. IT CAN B E FAT A L !
"serviceman's elbow ,"
any
signs o f shock
T 1 0 1
a
RF
T 1 203 (40m )
0 1 203
Q 1 203
T 1 202 ( 8 0 m )
T 1 20 1 ( 1 6 0 m )
0 1 2 0 1
Q 1 20 1
VCO
- 4 7-
Q10s
( P B - 1 702 )
u n i t
( P B - 1 7 1 0 )
u n i t
( P B - 1 7 1 1 )
Orysta l u n i t
T 1 20 5 ( 1 5 m )
T 1 206 ( 1 0 m A , 8 )
T 1 2os ( J J Y /W W V )
T l 3o5
X 1 3o5 ( 1 5 m )