Honeywell
COMPONENT MAINTENANCE MANUAL
PART NUMBER 964-0452
1I.B.1516A Page 38
Mar 30/01
23-12-01
3 Data Bus Amplifier Control, A33 —> Controller, A8
Signals VSWR, BITHF, BITAMP, CM50V, CMTEM, and CMAMP can be applied
to the data bus with MS3 = L and MRD = L via bus driver D11-A, and inquired
by Controller, A8. The generation and significance of these signals is explained
later in this section.
Signals CM50V, CMTEM, and CMAMP are also applied, directly and via RC
sections, time delayed at the inputs of 4-bit comparator, D5-A. Therefore, each
time the 3 signals change, the P and Q values of the comparator will differ for a
short time, and level L is present at output D5.6 for approximately 15 to 20µs.
The subsequent inverter, D8-A, connects through transistor, V1, and line CMINT
(X1.26), which is normally set to H by a pull-up resistor in Controller, A8, is set
to L level for 15 to 20µs. This causes Controller, A8, to inquire the CM messages
by data bus.
4 Control Branches
The voltages of signals FORV and REVV are referred to the ZERO signal in
Harmonic Filter A32. Although connected to ground in Harmonic Filter, A32, this
signal does not correspond exactly to the frame potential at Amplifier Control,
A33, owing to ground currents between the modules.
Consequently, the FORWARD and REVERSE signals are obtained with the 2
operational amplifiers, N1-A and N1-D, connected as differential amplifiers from
the FORV, REVV, and ZERO signals. These now form an exact measurement
of the forward and reverse power at the transceiver output.
The output power of the XK516D1 HF Transceiver is regulated by Amplifier
Control, A33, in such a way that a forward power of 400W
pep
(peak power con-
trol) or 125W
cw
(average power control) is present under normal operating con-
ditions. Two further control branches are activated in the event of mismatching
at the transceiver output, namely the VSWR control and reverse power control.
The dissipated power control and overcurrent control protect the amplifier from
damage in the event of a malfunction or abnormal operating conditions.
In conjunction with peak power control, the FORWARD signal is compared by
N3-B with the SPRFP control input, and the difference between the weighted
signals is amplified with N3-C. Depending upon the power stage, amplification
is converted with the 2 transistors,V32 and V33, and resistors, R71, R91, and
R89, in order to keep the loop gain of the entire control circuit constant. This
equation applies at the initiation threshold of the control:
10 * FORWARD – 6.46 * SPRFP = U
N3.8
≈ +0.3V (low power stage)
5.64 * FORWARD – 3.64 * SPRFP = U
N3.8
≈ +0.3V (medium power stage)
2.82 * FORWARD – 1.82 * SPRFP = U
N3.8
≈ +0.3V (high power stage)
For average power control, the FORWARD signal passes through a low-pass
filter with a limit frequency of 2Hz by means of R132, R135, R134, and C131,
and is then compared with the reference voltage, VREF, in operational amplifier,
N6-D. This equation applies at the initiation threshold of the control:
0.70 * average FORWARD value – 0.30 * VREF = U
N5.1
≈ +0.3V
(whereby VREF = +4.88)
Page 60
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