M860-00-Preliminary
T869 Circuit Operation
D2.7
Copyright TEL
30/06/98
2.3.1
Power Control
The DC voltages from the directional coupler representing forward and reflected power
are buffered by the two voltage followers, IC1 pins 1, 2 & 3 and pins 8, 9 & 10. Their out-
puts are summed at an integrator (IC5 pins 1, 2 & 3), which drives the series pass control
elements (Q19 & Q20).
Forward and reflected power are summed so that, under high output VSWR, the power
control turns the PA down. This is because the control loop adjusts for the same DC
voltage from the directional coupler that would have been present if there were no
reflected power.
2.3.2
Driver Power Level
The maximum output power of the T869 can be limited by placing a ceiling on the
driver output power level using RV69 (accessible through the side cover). For example,
if RV69 is set for a maximum output power of 50W, the range of adjustment using RV63
(front panel power adjust) will be 20 to 50W.
Note:
The driver power level clamp (RV69) is factory set to give a maximum
power output of 110W. The unit may be damaged if this level is increased.
2.3.3
Thermal Protection
At excessively high temperatures, the output power will automatically reduce to a pre-
set level (set by RV74), thus preventing the PA from overheating.
A thermistor controlled voltage divider (R85, R193) applies a voltage to a comparator
with hysteresis (IC1 pins 12, 13 & 14).
The output current from the comparator is summed into the power control network via
RV74 so that the power level to which the PA must turn down may be set.
2.3.4
Forward And Reverse Power Alarms
If forward power drops below, or reverse power rises above, presettable limits, alarms
may be triggered.
The alarm outputs are open drain configuration and are low under normal conditions
(i.e. forward and reverse power levels are normal).
IC1 pins 12, 13 & 14 and pins 5, 6 & 7 form comparators with thresholds adjusted via
RV48 and RV52 respectively. The inputs are from the forward and reverse power signals
from the directional coupler, buffered by IC1 pins 1, 2 & 3 and pins 8, 9 & 10. Thus, the
power levels at which the forward and reverse power alarms are triggered are defined
by RV48 and RV52 respectively.
Содержание T860 Series II
Страница 6: ...AII M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 12: ...A2 4 Mechanical M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 18: ...BII M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 20: ...B1 2 T865 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 30: ...B1 12 T865 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 32: ...B2 2 T865 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 42: ...B2 12 T865 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 56: ...B3 14 T865 Initial Tuning Adjustment M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 58: ...B4 2 T865 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 84: ...B5 20 T865 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 86: ...B6 2 T865 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 90: ...B6 6 T865 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 110: ...T865 Preliminary PCB Information T865 Grid Reference Index Page B6 26...
Страница 112: ...CII M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 114: ...C1 2 T867 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 148: ...C4 2 T867 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 154: ...C4 8 T867 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 156: ...C5 2 T867 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL Figure Title Page 5 1 RF Diode Probe Circuit 5 5...
Страница 170: ...C5 16 T867 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 172: ...C6 2 T867 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 176: ...C6 6 T867 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 204: ...T867 Preliminary PCB Information T867 Grid Reference Index Page C6 34...
Страница 206: ...DII M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 208: ...D1 2 T869 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 214: ...D1 8 T869 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 216: ...D2 2 T869 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 224: ...D3 2 T869 Initial Adjustment M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 230: ...D4 2 T869 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 233: ...M860 00 Preliminary T869 Fault Finding D4 5 Copyright TEL 30 06 98 replace A4 pages D4 5 D4 6 with A3 pages D4 5 D4 6...
Страница 234: ...D4 6 T869 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL replace A4 pages D4 5 D4 6 with A3 pages D4 5 D4 6...
Страница 238: ...D4 10 T869 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 240: ...D5 1 2 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 244: ...D5 2 2 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 254: ...D5 2 12 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 256: ...EII M860 00 Preliminary 30 06 98 Copyright TEL...
Страница 258: ...E1 2 T860 VCO PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...