Filter
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TS-440S
CIRCUIT DESCRIPTIO
N
I=1800, J=7244, K=19800, L=3239, M=4
1
fin = 0
.388 fsTD
1 1
When fIN = 30 MHz (USB mode) in formula 10 , f
IN
an
d
fSTD have the following relationship
:
I = 1800, J = 7244, K = 19800, L = 3239, M = 7
3
.'
. fIN = 0
.833
f
STD
1
2
Since the precision of the reference crystal oscillator use
d
in the TS-440 is 10 ppm (—10 to 50°C) and the receive
r
system has the characteristics shown in items i) and ii), th
e
total accuracy is stable at any point from 30 kHz to 30 MHz
.
The maximum amount of frequency shift is only +/— 30
0
Hz (see formula 12 )
. The characteristic shown in ite
m
iii) enables variable band functions such as IF shift to be im
-
plemented, using the microprocessor. The microprocesso
r
also is used to set carrier points by adjusting fcAR, and to se
t
and adjust the amount of IF shift
.
So far received frequencies in the SSB mode have been dis
-
cussed
. For receive modes other than SSB, and in transmi
t
mode, operating frequency is determined by the referenc
e
frequency and frequency division data
.
In CW receive mode,
fvco
is shifted down 800 Hz and use
d
as
fvco3
.
In AM or FM receive mode, fCAR generation i
s
stopped
. In FM receive mode, f
HET
is modulated by addin
g
audio signals to VCO5 from the microphone
. FSK (RTTY) i
s
transmitted in LSB mode and uses AFSK by adding audio sig
-
nals externally
.
The type of frequency displayed differs, depending on th
e
mode, as shown in Table 1
.
Mode
Displayed frequenc
y
USB, LSB, FS
K
C
W
AM, FM
Carrier point frequenc
y
Transmission carrier frequenc
y
IF filter center frequency
Table 1 Displayed frequencie
s
3
.
Receiver Circuit Descriptio
n
IC
2
C335
7
f
I F AMP
.
DE
T
Noise
S
O
CF
3
CFW455
Fig
. 3 Receiver circuit configuratio
n
CF I
Q7,
8
3SK73GRx2
IC
7
µPC2002V
S P
SSB
C
.F
AF P
A
CF
2
C
.
F
6