C OUNTER UNIT (PB- 1 978, PB- 1 979, PB- 1 980)
The premix lo cal signal from the PREM IX LOCAL
circuit is fed to amplifier Q230 1
( 3 SK5 1-03 ) ,
lo cat
ed on PB- 1 9 8 0 . The amplified signal is then fed to
waveshaper Q2 3 02
(MC l O l 1 6 ) .
Q1303
(MPS3 640)
acts as an interface between Q2302 and the TTL
circuitry . The signal is then fed to the counter gate,
Q1 304
( SN74 SOON).
The clock pulses are generated by Q23os
(MSM5564 ),
which produces a 6 5 5 . 3 6 MHz signal .
The sign al is divided by a factor of 2 1 7 , producing
a 5 Hz sign al which is fed to the counter gate.
The pulses which pass through the gate are fed to
d e cade counter Q2309
( SN74 1 96N),
which counts
1 0 Hz digits. In turn , Q23o2 - Q23o 7
( SN74LS 1 96N )
count 1 00 Hz, 1 kHz, 1 0 kHz, 1 00 kHz, 1 MHz,
and 1 0 MHz digits . The BCD output signal from
Q23o2 - Q130 7 is fed throu.gh drivers Q22o s - Q 1 2 1 3
(MSM56 1 )
to the display digits , DS2 1 0 1 - DS2 1 06
(HP 5082-7623 ) .
The system o f presetting the counter can best b e
e xplained by e x ample . F o r a frequen cy of 3 . 5 00
MHz LSB, the premix lo cal frequen cy is 1 2 . 4 8 6
M H z . The L S B preset code i s 9 1 .0 1 4 . 0 . 1 2 .486
+
9 1 .0 1 40 . 0
=
1 03 . 500. The " l " digit on the left
hand side is dropped (overflow), and the "O"
preceeding the "3 " causes a blanking signal to be
sent to the 1 0 MHz digit . The result is a frequency
o f 3 . 500 MHz , and this number is displayed .
Nominal Premix
L S B
Local Frequency
1 6 0m
1 0 . 4 8 7 5 - 1 0 . 9 8 7 5 ( M H z )
1 0 . 4 86 - 1 0 . 9 86 ( M H z )
80m
1 2 . 4 8 7 5 - 1 2 . 9 8 7 5
1 2 . 4 86 - 1 2 . 986
40m
1 5 . 9 8 7 5 - 1 6 . 4875
1 5 . 9 86 - 1 6 . 4 86
20m
2 2 . 9 8 7 5 - 23 . 4 8 7 5
22 . 986 - 23 . 4 8 6
1 5m
29 . 9 8 7 5 - 30 . 4875
29 . 9 86 - 30 . 486
l Om A
36 . 9875 - 37 . 4875
36 . 9 86 - 37 . 486
l Om B
37 . 4875 - 37 . 9 8 7 5
37 . 486 - 37 . 9 86
l Om C
37 . 9 8 7 5 - 38 . 4875
37 . 9 86 - 38 . 486
l Om D
3 8 . 4 8 7 5 - 38 . 9875
38 . 486 - 38 . 9 86
For USB, the p reset number is 9 1 .0 1 1 .0. F or a
frequency of 1 4 . 000 MHz USB, the manipul ation
is as follows : 9 1 .0 1 1
+
2 2 . 9 8 9 (Premix freq . )
=
1 1 4.000. The first digit is the overflow digit , and
the remaining digits are displayed. Note that the
second digit from the left is not zero , so no blank
ing signal is sent to the 1 0 MHz digit .
For a CW frequen cy of 2 1 .000 MHz, the p remix
frequency is 2 9 . 9 8 83 , and the preset frequen cy is
9 1 .0 1 1 . 7 . The manipulation is : 9 1. 0 1 1 . 7
+
2 9 . 9 8 8 3
=
1 2 1 . 0000 . The first digit is d ropped , and the
remaining digits are displayed .
The preset frequencies are programmed
by
Q230 7
and Q230 8
(µ PA54H )
and diode m atrix D2 3o6 -
D23 1 2
( 1 S 1 55 5 ) .
Please refer to Table
5
for
definition of the premix frequen cies for the various
bands.
The 5 volt supply is regulated by Q2310
(µPC
143 05 )
for the TTL circuitry . The DIM control
controls the emitter/colle ctor voltage at Q220 1
( 2SA496Y ) ,
to control the brightness o f the
digital display and lamps.
l O M H z l M H z l OOkHz lOkHz
lkHz
l OOH z
( Q z 2 0 7 )
( Q2 2 0 5 ) ( Q z 2 o s ) ( Q z 2 o d
( Q 2 2 0 3 )
( Q22 0 2 )
L S B
9
1
0
1
4
0
U S B
9
1
0
1
1
0
c w
9
1
0
1
1
7
Preset Number
,
Table 4
U S B
c w
1 0 . 489 - 1 0 . 9 89 ( M H z )
1 0 . 4883 - 1 0 . 9883 ( M H z )
1 2 . 489 - 1 2 . 989
1 2 . 4883 - 1 2 . 9883
1 5 . 9 89 - 1 6 . 489
1 5 . 9 8 8 3 - 16 . 4883
22 . 989 - 23 . 489
22 . 9 8 8 3 - 2 3 . 4883
29 . 9 89 - 30 . 489
29 . 9 8 8 3 - 30 . 4883
36 . 989 - 37 . 489
36 . 9883 - 37 . 4883
3 7 . 4 89 - 37 . 989
37 . 4883 - 37 . 9883
37 . 989 - 38 . 489
37 . 9 8 8 3 - 3 8 . 4883
3 8 . 489 - 38 . 989
38 . 4883 - 3 8 . 9 8 8 3
Table 5
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