Service manual

32
µPD 858 – Ex a mpl e
There is a range of AM/SSB rigs which includes the Cobra 138/139 XLR, Realistic
TTRC457/458/449 and "President Adams" that use the uPD858 PLL and can readily be
converted to the American "Novice" Band. This particular PLL uses BCD coding and the
standard "N" code values are 91 to 135. Although ten pins exist on this PLL, only eight are
fed by the channel switch. The codes on pins 22 and 19 do not change and are permanently
grounded. We need use only seven (*) of the eight, however, to get 40 unique location
codes. The resultant codes are thus :-
pins 22 - - - - - - - - 13 "N" *switch
* * * * * * *
40 0 1 0 0 1 1 0 1 0 1 135 35
39 0 1 0 0 1 1 0 1 0 0 134 34
38 0 1 0 0 1 1 0 0 1 1 133 33
37 0 1 0 0 1 1 0 0 1 0 132 32
36 0 1 0 0 1 1 0 0 0 1 131 31
35 0 1 0 0 1 1 0 0 0 0 130 30
34 0 1 0 0 1 0 1 0 0 1 129 29
33 0 1 0 0 1 0 1 0 0 0 128 28
32 0 1 0 0 1 0 0 1 1 1 127 27
31 0 1 0 0 1 0 0 1 1 0 126 26
31 0 1 0 0 1 0 0 1 1 0 126 26
30 0 1 0 0 1 0 0 1 0 1 125 25
29 0 1 0 0 1 0 0 1 0 0 124 24
28 0 1 0 0 1 0 0 0 1 1 123 23
27 0 1 0 0 1 0 0 0 1 0 122 22
26 0 1 0 0 1 0 0 0 0 1 121 21
25 0 1 0 0 0 1 1 0 0 0 118 18
24 0 1 0 0 1 0 0 0 0 0 120 20
23 0 1 0 0 0 1 1 0 0 1 119 19
22 0 1 0 0 0 1 0 1 1 1 117 17
21 0 1 0 0 0 1 0 1 1 0 116 16
…… … … … … … … … … … … ……… ……
…… … … … … … … … … … … ……… ……
09 0 1 0 0 0 0 0 0 0 1 101 01
08 0 1 0 0 0 0 0 0 0 0 100 00
07 0 0 1 0 0 1 1 0 0 0 98 58
06 0 0 1 0 0 1 0 1 1 1 97 57
05 0 0 1 0 0 1 0 1 1 0 96 56
04 0 0 1 0 0 1 0 1 0 1 95 55
03 0 0 1 0 0 1 0 0 1 1 93 53
02 0 0 1 0 0 1 0 0 1 0 92 52
01 0 0 1 0 0 1 0 0 0 1 91 51
The "N" codes to shift from 29.965 MHz up to 28.105 MHz are easily worked out as in
the following table. The Eprom codes need consist only of the first seven BITs (+) since
the three Most Significant Bits do not need to change and can be wired permanently high or
low, as indicated. The eighth output from the Eprom may be left unconnected since it is not
required.