Copyright TEL
31/01/96
2.3
Mixer
(Refer to Figure 2.2.)
IC301 is a high level mixer requiring a local oscillator (LO) drive level of +17dBm (nom-
inal). The voltage controlled oscillator (VCO) generates a level of +22dBm (typical) and
this is fed to the mixer via a 2dB attenuator pad. A diplexer terminates the IF port of the
mixer in a good 50 ohms, thus preventing unnecessary intermodulation distortion.
2.4
IF Circuitry
(Refer to Figure 2.2.)
Losses in the mixer are made up for in a tuned, common gate, post mixer amplifier
(Q303). Several stages of amplification and filtering are employed in the IF circuitry.
The first crystal filter is a 4-pole device (&XF301) which is matched into 50 ohms on both
its input and output ports. This stage is followed by a two-stage amplifier which is
designed as a 50 ohm block, after which the signal is mixed down to 455kHz with the
second local oscillator (20.945MHz).
The 455kHz signal is filtered using a six-pole ceramic filter (&XF303) before being lim-
ited and detected.
The second IF mixer, limiter, detector and RSSI is in a 16-pin IC (IC303). Quadrature
detection is employed, using L319, and the recovered audio on pin 7 of IC303 is typi-
cally 0.3V p-p for 60% system deviation.
Содержание T830 Series
Страница 10: ...31 01 96 Copyright TEL...
Страница 12: ...31 01 96 Copyright TEL...
Страница 16: ...31 01 96 Copyright TEL...
Страница 20: ...31 01 96 Copyright TEL...
Страница 22: ...31 01 96 Copyright TEL...
Страница 24: ...31 01 96 Copyright TEL...
Страница 28: ...31 01 96 Copyright TEL...
Страница 30: ...31 01 96 Copyright TEL...
Страница 32: ...31 01 96 Copyright TEL...
Страница 38: ...31 01 96 Copyright TEL...
Страница 40: ...31 01 96 Copyright TEL...
Страница 50: ...31 01 96 Copyright TEL Figure Title Page 3 1 3 2 Channel DIP Switch Setting Test Equipment Set up 3 3 3 6...
Страница 62: ...31 01 96 Copyright TEL...
Страница 68: ...31 01 96 Copyright TEL...
Страница 70: ...31 01 96 Copyright TEL...
Страница 84: ...31 01 96 Copyright TEL...
Страница 88: ...31 01 96 Copyright TEL...
Страница 94: ...31 01 96 Copyright TEL...
Страница 98: ...31 01 96 Copyright TEL...
Страница 99: ...M830 00 T835 PCB Information B6 2 13 Copyright TEL 31 01 96 T835 PCB Layout Top Side 220 01186 02...
Страница 100: ...B6 2 14 T835 PCB Information M830 00 31 01 96 Copyright TEL T835 PCB Layout Bottom Side 220 01186 02...
Страница 101: ...M830 00 T835 PCB Information B6 2 15 Copyright TEL 31 01 96 T835 Test Points Options Top Side 220 01186 02...
Страница 102: ...B6 2 16 T835 PCB Information M830 00 31 01 96 Copyright TEL T835 Test Points Options Bottom Side 220 01186 02...
Страница 103: ...M830 00 T835 PCB Information B6 2 17 Copyright TEL 31 01 96 Sheet 1 T835 Synthesiser 220 01186 02...
Страница 104: ...B6 2 18 T835 PCB Information M830 00 31 01 96 Copyright TEL 6K8S 3K9S Sheet 2 T835 Audio Processor 220 01186 02...
Страница 105: ...M830 00 T835 PCB Information B6 2 19 Copyright TEL 31 01 96 Sheet 3 T835 Regulator 220 01186 02...
Страница 106: ...B6 2 20 T835 PCB Information M830 00 31 01 96 Copyright TEL 8K2S Sheet 4 T835 Receiver 220 01186 02...
Страница 108: ...31 01 96 Copyright TEL...
Страница 110: ...31 01 96 Copyright TEL...
Страница 116: ...31 01 96 Copyright TEL...
Страница 118: ...31 01 96 Copyright TEL...
Страница 140: ...31 01 96 Copyright TEL...
Страница 142: ...31 01 96 Copyright TEL...
Страница 148: ...31 01 96 Copyright TEL...
Страница 160: ...31 01 96 Copyright TEL...
Страница 162: ...31 01 96 Copyright TEL...
Страница 166: ...31 01 96 Copyright TEL...
Страница 172: ...31 01 96 Copyright TEL...
Страница 180: ...31 01 96 Copyright TEL...
Страница 181: ...M830 00 T836 837 PCB Information C6 2 17 Copyright TEL 31 01 96 T836 837 PCB Layout Top Side 220 01178 02...
Страница 182: ...C6 2 18 T836 837 PCB Information M830 00 31 01 96 Copyright TEL T836 837 PCB Layout Bottom Side 220 01178 02...
Страница 183: ...M830 00 T836 837 PCB Information C6 2 19 Copyright TEL 31 01 96 T836 837 Test Points Options Top Side 220 01178 02...
Страница 184: ...C6 2 20 T836 837 PCB Information M830 00 31 01 96 Copyright TEL T836 837 Test Points Options Bottom Side 220 01178 02...
Страница 185: ...M830 00 T836 837 PCB Information C6 2 21 Copyright TEL 31 01 96 Sheet 1 T836 837 Synthesiser 220 01178 02...
Страница 186: ...C6 2 22 T836 837 PCB Information M830 00 31 01 96 Copyright TEL Sheet 2 T836 837 Audio Processor 220 01178 02...
Страница 187: ...M830 00 T836 837 PCB Information C6 2 23 Copyright TEL 31 01 96 Sheet 3 T836 837 Regulator 220 01178 02...
Страница 188: ...C6 2 24 T836 837 PCB Information M830 00 31 01 96 Copyright TEL Sheet 4 T836 837 Exciter PA 220 01178 02...
Страница 190: ...31 01 96 Copyright TEL...
Страница 192: ...31 01 96 Copyright TEL...
Страница 196: ...31 01 96 Copyright TEL 1 3 Versions Description Version 10 136 174MHz...
Страница 198: ...31 01 96 Copyright TEL...
Страница 204: ...31 01 96 Copyright TEL...
Страница 212: ...31 01 96 Copyright TEL...
Страница 218: ...31 01 96 Copyright TEL...
Страница 220: ...31 01 96 Copyright TEL...
Страница 222: ...31 01 96 Copyright TEL...
Страница 224: ...31 01 96 Copyright TEL...
Страница 228: ...31 01 96 Copyright TEL...
Страница 232: ...31 01 96 Copyright TEL...
Страница 236: ...31 01 96 Copyright TEL...
Страница 238: ...31 01 96 Copyright TEL...
Страница 240: ...31 01 96 Copyright TEL...
Страница 243: ...T800 Memory PCB IPN 220 01144 00 Top Side Copyright TEL 31 01 96...
Страница 244: ...31 01 96 Copyright TEL T800 Memory PCB IPN 220 01144 00 Bottom Side...
Страница 245: ...M830 00 T800 Memory PCB Information E2 5 Copyright TEL 31 01 96 T800 MEMORY T800 Memory 220 01144 00...
Страница 246: ...E2 6 T800 Memory PCB Information M830 00 31 01 96 Copyright TEL...
Страница 250: ...31 01 96 Copyright TEL...
Страница 251: ...T830 VCO PCB IPN 220 01176 01 Bottom Side Copyright TEL 31 01 96...
Страница 252: ...31 01 96 Copyright TEL T830 VCO PCB IPN 220 01176 01 Top Side...
Страница 253: ...M830 00 T830 VCO PCB Information E3 7 Copyright TEL 31 01 96 T830 VCO 220 01176 01...
Страница 254: ...E3 8 T830 VCO PCB Information M830 00 31 01 96 Copyright TEL...
Страница 256: ...31 01 96 Copyright TEL...
Страница 260: ...31 01 96 Copyright TEL...
Страница 264: ...31 01 96 Copyright TEL...
Страница 272: ...31 01 96 Copyright TEL...
Страница 278: ...31 01 96 Copyright TEL...
Страница 284: ...31 01 96 Copyright TEL...