M Aintenance And Alig Nment; Equipment Required - Yaesu FT-901DM Instruction Manual

WARNING
DANGEROUS VOLTAGES
WITHIN THI S TRANSCEIVE R . USE EXTREME
C AUTI ON WHEN WORKING ON THE TRANS­
CEIVER WITH THE COVERS REMOVE D . DIS­
CHARGE AL L CAPACITORS BY SHORTING
THEM TO GROUND WITH AN INSULATED
SCREWD RIVE R AFTE R POWE R HAS BEEN
REMOVED , AND OBSERVE OTHE R N O RMAL
SAFETY PRECAUTION S .
CAUTION
Never op e rate this transceiver in the transmit
mode wi thout a matched antenna or dummy l oad
connected to the antenna receptacle on the rear
panel. It is possible to damage the final amplifier
tub e s and the pi network com p on ents i f the trans­
ceiver is operated without the proper load termi­
nation.
GENERA L
This transceiver has been care fully aligne d and
tested at the fact ory and, with n ormal usage ,
should n o t require other than the usual attention
given t o electronic equipment. Service or realign­
ment of a maj or c omponent may require subse­
quent r ealignment ; under
th ough , should realignment be attempted unless
the operation o f the transceiver is fully under­
stood, the malfun c tion has been carefully ana­
lyzed , and the fault has definitely been traced to
misalignm ent. Service work should only be per­
formed b y experienced personnel using the proper
test equipment .

EQUIPMENT REQUIRED

( 1 )
RF Signal Generator : Hewlett-Packard Model
..
606A or equivalen t , with one volt outpu t
at 5 0 Ohms, and frequency coverage to 3 0
MHz .
(2) Vacuum Tube Voltmeter (VTVM ) : H e wlett­
Packard M odel 4 1 0B or equivalent, with an
RF p robe good to 40 MHz .
(3 ) Dummy Load : Yaesu model YP- 1 5 0 o r equiv­
ale n t , with 5 0 Ohm non-reactive load imped­
ance rated to 1 5 0 watts average p ower.

M AINTENANCE AND ALIG NMENT

ARE PRESENT
n o circum stances ,
- 41 -
(4) AF Signal Generato r : Hewlett-Packard Model
2 00AB or equivalent.
( 5 ) A general · c overage receiver covering the fre­
quency range from 3 to 3 0 MHz with a 1 00
kHz calib rator.
(6) A frequency counter, Yaesu Model YC-5 00
or equivalent, with re solution to . 0 1 kHz
and frequency coverage to 30 MHz .
1 . S-METER SEN SITIVITY ADJ USTMENT
Place the transceiver in the receive m o d e and
connect a signal generator to the antenna terminal
of the transceiver. Set the signal generator to
1 4200 kHz with an output of 6 dB. Tun e the
transceiver to 1 4 200 kHz for a maximum reading
on the S-me ter. The S-meter should just start to
rise with a 6 d B input. I f no deflection is observed,
adjust VR4 0 2 to ob tain a slight meter d e flection.
Apply 1 00 d B input to the antenna terminal ;
the S-me ter should read S9 + 60 d B . If n o t , adjust
VR4 0 1 . V R 4 0 1 and VR4 0 2 are located on PB-
1 7 04 .
When the transceiver is tuned to 1 4 200 kHz, the
I
00 kHz c alibrator signal will indicate approxi­
I
mately S 9 + 0 d B when MARK switch is acti­
vate d .
T4o3
X401
0406
Q404
T4o4
I F u n i t (PB - 1 704)
T <l O l
0 4 1 0
Q401