Kenwood TM-731A Service Manual page 7

TM-731A/E
© General
Except for the microphone amplifier and APC {Automatic Power
220K
| 5
| y yt
| 16v
O
| O
m ,
€ 4
=
gle TO
.
j
r "TTP RBS
Qi: 28c4ai6ly) ICl | NJM4558M |
t——- 144 PLL
aS || ghee wee ne eee CHP - oo
F i g . 9 M o d u l a t i o n © | g s o m o l
ig. odulation Circuit
| 430 MDI aay nue TX-RX UNIT
* Preamplifier Stage Circuit
; .
© Power Amplifier Circuit
A three-stage linear amplifier is used in both the 144 MHz and
The drive signal is fed to the power modules and amplified to
430 MHz bands. Due to its wideband design, this linear am-
the required levels. It then passes through the TX/RX switching
plifier provides stable drive output without adjustment.
diode and a filter and is transmitted via the antenna.
. Rating
Item
Symbol | Tc (°C) | Unit
Conditions
5 :
_
;
S-AV17
: M57788M
Operating voltage
Vee
25 i V
16 °
17
Current consumption
lec 25 A
14
14
Input power
Pin
25 Ww
Zo =Z_.=50 0
0.6
0.6 (Vcc12 13.8 V)
Output power
Po 25 WwW
Zo=Z.=50 0
65
55
. 'Operating case tem= "To (op) |
. oe ~ "pose
.
"362371607
menses osensann soar
ges papain
perature
Storage temperature Tstg
ae
: —40~ +110
-40~+110
Table 7 Maximum Ratings of Power Modules
* APC and SWR (Standing Wave Retio) Protection Circuits
The APC (automatic transmit output control) circuit and pro-
ching at the CM (Capacitance Matching) coupler, detects it,
tection circuit have independent detectors in both bands. The
and feeds the result to the hybrid IC.
contro! circuit is a common
hybrid IC.
The hybrid IC controls the power transistor Q5 : 2SD1406
(Y)
The APC detects the output from the power module and feeds
in the drive stage, controls the drive transistor and the second
the result to the hybrid IC. The SWR protection circuit extracts
pin of the power module, and thus varies the transmitter output.
a portion of the reflected wave generated by antenna mismat-