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B2.8
T865 Circuit Operation
M860-00-Preliminary
30/06/98
Copyright TEL
The audio can also be disabled using the "RX-DISABLE" inputs, pads 225 or 228, having
connected the "RX-DISABLE" link between pins 1 & 2 of PL260. An adjustable time
delay (RV220) is provided on these lines. In order to disable the audio, either pad must
be pulled to 0V.
An undedicated relay is provided (RL210) for transmitter keying or other functions and
this can be operated from the mute line by linking PL270.
2.8
Power Supply And Regulators
(Refer to the regulators circuit diagram (sheet 6) in Section 6.)
Figure 2.4 T865 Power Supply And Regulators Block Diagram
The T865 is designed to operate off a 10.8-16V DC supply (13.8V nominal). A 5.3V regu-
lator (IC630) runs directly from the 13.8V rail, driving much of the synthesiser circuitry.
It is also used as the reference for a DC amplifier (IC640, Q630 & Q620) which provides
a medium current capability 9V supply.
A switching power supply, based on Q670 and Q660, runs off the 9V supply and pro-
vides a low current capa20V supply. This is used to drive the synthesiser loop
filter (IC740), giving a VCO control voltage of up to 20V.
The 13.8V supply drives both output audio amplifiers without additional regulation. A
separate 5V regulator (IC610) drives the microprocessor and associated digital circuitry.
The output of this regulator is monitored by the Low Voltage Interrupt (LVI) circuit
(IC650).
LVI
LVI
5V
Reg
DC
Amp
Switching
PS
5V Dig
Reg
µP
Reset
13.8V
Nom.
5V
5V Dig
9V
20V
13.8V Nom.
From Rear
D-Range 1
Summary of Contents for T860 Series II
Page 6: ...AII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 12: ...A2 4 Mechanical M860 00 Preliminary 30 06 98 Copyright TEL...
Page 18: ...BII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 20: ...B1 2 T865 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 30: ...B1 12 T865 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 32: ...B2 2 T865 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Page 42: ...B2 12 T865 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Page 56: ...B3 14 T865 Initial Tuning Adjustment M860 00 Preliminary 30 06 98 Copyright TEL...
Page 58: ...B4 2 T865 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Page 84: ...B5 20 T865 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 86: ...B6 2 T865 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 90: ...B6 6 T865 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 110: ...T865 Preliminary PCB Information T865 Grid Reference Index Page B6 26...
Page 112: ...CII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 114: ...C1 2 T867 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 148: ...C4 2 T867 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Page 154: ...C4 8 T867 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Page 170: ...C5 16 T867 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 172: ...C6 2 T867 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 176: ...C6 6 T867 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 204: ...T867 Preliminary PCB Information T867 Grid Reference Index Page C6 34...
Page 206: ...DII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 208: ...D1 2 T869 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 214: ...D1 8 T869 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 216: ...D2 2 T869 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Page 224: ...D3 2 T869 Initial Adjustment M860 00 Preliminary 30 06 98 Copyright TEL...
Page 230: ...D4 2 T869 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 238: ...D4 10 T869 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 240: ...D5 1 2 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 244: ...D5 2 2 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 254: ...D5 2 12 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 256: ...EII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 258: ...E1 2 T860 VCO PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...