Sony Pll CX7961A - Description for use in radio ATS818, RK765, DX390
The datasheet for PLL CX7961A is impossible to find in internet.
But i have write a program in machine code 8085 CPU, for capture the info in
directly trasparent synchronism (CPU to PLL - RK765) with my old PC M10
or Tandy 102. It is very laborious, but now i am aware the infos. These is:
1) The better system to wideband is operate directly on the single bit
(or more bit attached), during a normal reception in continuous mode.
2) Clock CPU -> PLL. about 4,6 Khz.
3) Wen power on the radio RK765, the Cpu send to Pll a 40 bits string. The first
20 bits to prepare the PLL register. The second 20 bits to write in PLL register the
old last frequency in normal reception and last 3 bit mode Pll.
See schema on article (Modifiche ATS818).
4) Wen a normal selection of frequency or bands the Cpu send to Pll only 20 bit string.
Description of the 20 bits. First (17 bits) = Frequency for the Pll in this mode:
Decimal = Freq. IF Khz (55.845 - 8) + Freq. Rx.
Example, Rx in 7.033 Khz = 55837 + 7033 = 62.870 Khz (Freq. register Pll).
62.870 = Bin. 01111010110010110 (17 bit).
But in send mode Cpu to Pll the first bit is (d0) and last bit is (d16)
The remaining 3 bits = 001 (For control mode Pll).
In FM mode the IF change 55.845 Khz to 10.700 Khz. The base number
is (10.700 - 8) = 10.692. First 17 bits = 10692 + Frequency Rx (Khz).
Example, Rx in 99,7 Mhz = 10692 + 99700 = 110.392 Khz (Freq. register Pll).
Bin. = 11010111100111000 (17) bit).
It is important to change a bit (set or reset) on the string always during the
frequency selection . Also is important to know the 17 bit string, first to change
a single bit with my system (at89c2051 Cpu) in trasparent control.
The basic program (see Sharp Organizer…IQ-7100.. Freq..ATS818) to calc a 17 bit
string for extra new frequency.
(Visual d16 to d1, d0 not present, because display is mini).
Example i wish to receive 31.200 Khz. The bin. string is : 10101001111111101
or 55837 + 31200 = 87.037 Khz freq. Pll.
On the 17 bit string, d14 = 1. If i clear the bit d14 then the frequency result =
31.200 Khz - 16.384 Khz = 14.816 Khz. Set receiver on this frequency and
run my (AT89C2051 system) in this mode: Press set bit Frequency, cont the number
(nr.15 + 16.384 Khz) of flash led and to leave.
Example for low frequency. I wish to receive 77 Khz. The bin. string is:
01101101001101010 or 55837 + 77 = 55.914 Khz freq. Pll.
On note d10 = 0. If i set the bit d10 = 1, then the frequency result = 77 + 1024 =
1.101 Khz (MW band). Or set bit d8 = 1, the freq. Rx is 77 + 128 = 205 Khz (LW band).
For MW band, flash selection is nr.4 and LW band is nr. 2.
In all case it is necessary after selection, to press the band or tuning a step receiver.
For reset Cpu system and active normal freq. reception, power off/on
(at89c2051 system), for return in trasparent mode.
Reference nr. flash led to change bit (decimal):
1 = - 64 2 = - 128 3 = - 256 4 = - 1024 5 = - 2048 6 = - 4096 7 = - 8192
8 = - 16384 9 = + 256 10 = + 512 11 = + 1024 12 = + 2048 13 = + 4096 14 = + 8192
15 = + 16384 16 = + 32768.
Note: For receiver the 50-51 Mhz, set the RX on 17.232 - 18.232 Khz and then
selection flash led nr.16 + 32.768 Khz and press SW.
Input antenna in extra plug Rca, (see ..Antenna banda 30-60 Mhz su ATS818).
For receiver in addition (28.310 - 34.310 Khz), the 140-146 Mhz (Normal sensibility),
set the RX on 11.926 - 17.926 Khz and then selection flash led nr.15 + 16.384 Khz.
Use original stilus antenna (see...RK765.. Come ricevere i..(144-146 Mhz)
I hope my description is helpful for alls interested.
73, Emil - ik1wjq
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