TS-440S
6
CIRCU IT D ESCRI PTION
I = 1 800,
J
= 7244, K = 1 9800, L = 3 2 39, M = 4 1
:. f1N = 0 . 388 fsrn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1
When f1N = 30 MHz (USB mode) in formula
1 0 , f1N and
fsrn have the following relationship:
I = 1 800,
J
= 7244, K = 1 9800, L = 3 2 39, M = 73
:. f1N = 0 . 8 3 3 fsrn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2
Since the precision of the reference c rystal oscillator used
in the TS-440 is 1 0 ppm ( - 1 0 to 50°C) and the receiver
system has the characteristics shown in items i) and ii), the
total accu racy is sta ble at any point from 30 kHz to 30 MHz .
The maximum amo u nt of frequency shift is o n ly
+I
-
300
Hz (see formula
1 2 ). The cha racteristic shown in item
iii) enables variable band functions such as IF shift to be im
plemented, using the microprocessor. The microprocessor
also is used to set carrier points by adjusting
fcAR,
and to set
and adjust the amou nt of IF shift.
So far received freq uencies in the SS B mode have been dis-
3 . Receiver Circuit Description
F M
030-33
F2
CFI
CF 3
CFW 455
07,8
3 S K 7 3GRx2
cussed . For receive modes other tha n SS B, and in transmit
mode, operating freq uency is determined by the reference
frequency and freq uency division dat a .
In CW receive mode,
fvco
i s shifted d o w n 8 0 0 H z and used
as
fvco3.
In A M or FM receive mode,
fcAR
generation is
stopped . In F M receive mode, fHET is mod u l ated by adding
audio sig n als to VC 0 5 from the microphon e . FSK (RTTY) is
transmitted in LSB mode and uses AFSK by adding audio sig
n als externally .
The type of frequency displayed differs, depe nding on the
mode, as shown in Ta ble 1 .
M o d e
D i s p l ayed freq u e n c y
U S B , L S B , F S K
C a rrier p o i n t f r e q u e n c y
cw
Tra n s m i s s i o n c a rrier freq u e n c y
A M , F M
IF f i l t e r c e n t e r freq u e n c y
Table 1 Displayed frequencies
012
2SC 2459BL
IC 7
Fig . 3 Receiver circuit configuration