Kenwood TM-2550A Service Manual page 3

Li2 CFY455S
CIRCUIT DESECRIPTION
TM-2550A/E,2530A
Input/Output characteristics Principle of operation of window comparator
of L12.
8R CENTER DATECTOR
9 (X59-1030-10) +e
eo
Et: 4.1V—0 (4.06V) |
" 1 6 se
i - 7 1 ,
Rt 1 ae et
Ct 5 101 (2/2) Et E2 et &1 £2
y OR? ei=4.1Vi0e 1C1(2/2)
q Wr
C4 01
Qi b> ]}~ C4172) oe beg
4iv_ 23 2
g = | J. E2
3 -e
q 3 @ : Set voltage at time when .
82V Ns detuning from 3kHz. .
[
ST
(About 0.04V)
Ei e2 et
—_
10 ; 4
ry = a¢ Center detection
od Set to "H" when signals received from |
outside is within about + 3kHz. BD : Center stop signal
Set to "L" when in SOL OPEN mode at center.
z
[CONT-14
- BD]
e
8R n
L +4 SOL CONTROL
3
9
{(X89- 1040-10)
§ at | cunemmens a
Q6 tusned on when in SQL. OPEN 4 turned on when
mode while searching vacant channels. in SQL OPEN mode
Lis = R1 R5 at center.
a
NOISE
FILTER '|
as a
7 | D5 10 RG 1 Q3 turned on
NOISE when in SQL :
P FM DET 5 turned on when signal
| iF AM KY AMP. H + Set to "H" when in OPEN mode. received from outside is
© ° SQL OPEN mode. at center.
Le ———- a 5 " Set to about OV when in
: Ic. SQL CLOSE or TX mode.
[ " . omeatiien.® - ;
I NOISE DET.
| awit th. Q39 is cut off for muting when in SQL
| 6 x CLOSE, TX, or ALERT mode. 1
| ° ox
| , " o | C103 «C104 At 1 A se
F PA
| c100 3 + im
"
' 7
| AF VR
10
—
a1
Q2 turned on when searching Q1 is turned on and O9
vacant channels to change is cut off for muting when °
Q3 Q2| >" from SQL to VR3. in TX or ALERT mode. Set to "L" normally.
mode. Set to "H' when searching
vacant channels in DCL
04 RS OPERATION mode.
> a Jz |
Q3 turned off when RT 2 T Sas
searching vacant —ed
channels. ZL °
7 7
ALERT, VACANT CH. (X§9- 1020-10) |
Fig. 2 Center datector, Alert, Vacant CH, SQL control circuit