A07B500S manual
Pag. 40
5.8
LCDP board
All the input and output data concerning the transmitter are controlled by the DLCD board, to
which also the keyboard and the LCD display control and visualisation board are connected.
A Motorola microprocessor 68HC11 controls the whole transmitter through the J1 and J2
connectors: the keyboard is multiplexed by U6 and U9.
All the values to be measured are fed to the E port with the proper protections against overvoltages
or polarity inversions (DZ1 - … - DZ8 diodes).
A self supplied clock (U21) is connected to the D port through three lines.
The microcontroller serial port is switched by U2 and U25 on the RS232 connector placed on the
front panel, on the rear one and on the RS485 port on the rear as well; the driver for RS232 is made
of U18 (MAX232), while the one for RS485 is U19 (SN75176).
The ports B, C and F of the µP are connected to an external 128KB flash memory, where the TX
management program is present, which at any time can be loaded through the front COM1 by any
PC.
The G port is for all the outputs (pre-emphasis enabling, mono-stereo, alarms, measurement
selection, etc.). The two external outputs for the alarms are uncoupled by two reed relays with
closed or opened contacts selected by two jumpers placed on the MBA board (Z1 and Z2).
A part of the H port is used, as output in PWM, to control the forward and reflected power and the
fine correction of the transmission frequency. The PWM mean value is detected with accuracy, to
avoid errors due to supply voltage variations or saturation and interdiction of the H port outputs.
The operational amplifiers U11,U12,U13 and U14 are part of the power control circuit .
The
control loop has a cut frequency of several hundreds Hertz, so in few milliseconds the power can be
controlled and eventually reduced or eliminated in extreme events. The microprocessor therefore
provides to the loop the forward and reflected power reference values, the quantities to be checked
are PWR and PWD, coming from the directional coupler, while the over stated operational
amplifiers represent the error amplifier.
The LCD display, driven by the A port, is a 40x4 alphanumerical characters type and allows an
useful displaying of data and transmitter settings.
5.9
AMP500 module
The 500 Watt amplifier, as already noted, is comprised of two 3dB coupled amplifiers. The
input coupler is made of fiberglass-stripline; input power is splitted in two parts, running on a
symmetrical path before the final sum by means of a last 3dB coupler. The amplifier circuit is
preceded by a phase and amplitude equalizer which allows the vector sum output to be regulated for
a maximum without sacrificing adaptation circuits. A high-Q impedance transformer with a 9/1
ratio precedes the MOS-FET input, adapting the impedance input. The bias current is thermally
Summary of Contents for A07B500S
Page 15: ...A07B500S manual Pag 15 A07B500S TRANSMITTER BLOC DIAGRAM...
Page 16: ...A07B500S manual Pag 16 A07B500S POWER SUPPLY BLOC DIAGRAM...
Page 27: ...A07B500S manual Pag 27...
Page 34: ...A07B500S manual Pag 34...
Page 42: ...A07B500S manual Pag 42 ADJUSTMENT4 6 1 Module PWN PW500 power supply...
Page 46: ...A07B500S manual Pag 46...
Page 68: ...A07B500S manual Pag 68 fig 9a...
Page 69: ...A07B500S manual Pag 69 fig 9b...
Page 70: ...A07B500S manual Pag 70 fig 9c...
Page 73: ...A07B500S manual Pag 73 fig 9c...
Page 74: ...A07B500S manual Pag 74 DIAGRAMS AND LAYOUTS...
Page 75: ...A07B500S manual Pag 75 PWN BOARD POWER SUPPLY...
Page 76: ...A07B500S manual Pag 76 PWN BOARD POWER SUPPLY...
Page 79: ...A07B500S manual Pag 79 AUDIOIN BOARD AUDIO INPUTS...
Page 80: ...A07B500S manual Pag 80 AUDIOIN BOARD AUDIO INPUTS...
Page 81: ...A07B500S manual Pag 81 AUDIOIN BOARD AUDIO INPUTS...
Page 85: ...A07B500S manual Pag 85 LCDP BOARD DISPLAY DRIVER...
Page 86: ...A07B500S manual Pag 86 LCDP BOARD DISPLAY DRIVER...
Page 90: ...A07B500S manual Pag 90 MBP BOARD MOTHER BOARD...
Page 91: ...A07B500S manual Pag 91 MBP BOARD MOTHER BOARD...
Page 92: ...A07B500S manual Pag 92 MBP BOARD MOTHER BOARD...
Page 93: ...A07B500S manual Pag 93 MBP BOARD MOTHER BOARD...
Page 97: ...A07B500S manual Pag 97 258 1 74HC00N Gate 2 Input NAND U23 KEY BOARD KEY...
Page 98: ...A07B500S manual Pag 98 KEY BOARD KEY...
Page 100: ...A07B500S manual Pag 100 SINTD BOARD VCO OSCILLATOR...
Page 101: ...A07B500S manual Pag 101 SINTD BOARD VCO OSCILLATOR...
Page 104: ...A07B500S manual Pag 104 Total DMPX BOARD STEREOCODER...
Page 105: ...A07B500S manual Pag 105 DMPX BOARD STEREOCODER...
Page 108: ...A07B500S manual Pag 108 AGC BOARD AUDIO AUTOMATIC GAIN CONTROL...
Page 109: ...A07B500S manual Pag 109 AGC BOARD AUDIO AUTOMATIC GAIN CONTROL...
Page 112: ...A07B500S manual Pag 112 MBP500 BOARD MBP A500 CONNECTION...
Page 113: ...A07B500S manual Pag 113 MBP500 BOARD MBP A500 CONNECTION...
Page 115: ...A07B500S manual Pag 115 A15 BOARD RF DRIVER AMPLIFIER...
Page 116: ...A07B500S manual Pag 116 A15 BOARD RF DRIVER AMPLIFIER...
Page 118: ...A07B500S manual Pag 118 DC250 BOARD DIRECTIONAL COUPLER...
Page 119: ...A07B500S manual Pag 119 DC250 BOARD DIRECTIONAL COUPLER...
Page 122: ...A07B500S manual Pag 122 A500 BOARD POWER AMPLIFIER A500 BOARD POWER AMPLIFIER...
Page 123: ...A07B500S manual Pag 123 A500 BOARD POWER AMPLIFIER...
Page 124: ...A07B500S manual Pag 124 PW500 BOARD AUXILIARY POWER SUPPLY...
Page 125: ...A07B500S manual Pag 125 PW500X BOARD AUXILIARY POWER SUPPLY...
Page 126: ...A07B500S manual Pag 126 PW500 BOARD AUXILIARY POWER SUPPLY...
Page 127: ...A07B500S manual Pag 127 PW500X BOARD AUXILIARY POWER SUPPLY...
Page 130: ...A07B500S manual Pag 130 LPF500 BOARD RF LOW PASS FILTER...