Copyright TEL
31/01/96
3.6
Alignment Of Receiver Front End And IF
Note 1:
In this and following sections deviation settings are given first for wide
band sets, followed by settings in brackets for narrow band sets [ ].
Note 2:
Frequency Range
136-156MHz:
With the power supply switched off, solder bridge links
1-6 and link B in the front end.
148-174MHz:
Solder bridge link A and ensure links 1-6 and link B are
not connected.
Align the synthesiser as instructed in Section 3.5. For multichannel operation the
receiver should be aligned on a frequency in the middle of the required band.
Inject a strong on-channel RF signal with 3kHz deviation [1.5kHz] at 1kHz into
the antenna socket and adjust L304, L305, L309 & L310 to give best sinad.
Continually decrease the RF level to maintain 12dB sinad.
Roughly tune IF coils L315/L316/L317, VC301 and quad coil L319 for best sinad.
While maintaining a low level unmodulated RF input to the receiver, loosely cou-
ple into the first IF an additional high level signal at 21.4MHz - a beat note will be
heard.
Trim the synthesiser TCXO (IC2) for zero beat.
Readjust the front end doublets (L304, L305, L309 & L310) to give best sinad.
Change the RF signal level to -75dBm and modulate with 3kHz deviation
[1.5kHz] at 1kHz.
Connect an oscilloscope probe to the RSSI test point (pad 115 or 125) and connect
plugs PL101 and PL103 to give a flat audio response (refer to Section 3.3).
Readjust IF coils L315/L316/L317, VC301 and quad coil L319 to give a maximum
amplitude response on the oscilloscope with minimal amplitude modulation.
Further adjust these coils, along with L319, for minimum audio distortion, ensur-
ing that the 455kHz level (on the oscilloscope) does not fall significantly.
Check that the distortion reading is less than 2%.
Reconnect plugs PL101 and PL103 to give a de-emphasised audio response (if
required) and reduce the RF level until 12dB sinad is reached. The receiver sensi-
tivity should be better than -117dBm, assuming that the audio levels are not being
overdriven (refer to Section 3.8).
Summary of Contents for T830 Series
Page 10: ...31 01 96 Copyright TEL...
Page 12: ...31 01 96 Copyright TEL...
Page 16: ...31 01 96 Copyright TEL...
Page 20: ...31 01 96 Copyright TEL...
Page 22: ...31 01 96 Copyright TEL...
Page 24: ...31 01 96 Copyright TEL...
Page 28: ...31 01 96 Copyright TEL...
Page 30: ...31 01 96 Copyright TEL...
Page 32: ...31 01 96 Copyright TEL...
Page 38: ...31 01 96 Copyright TEL...
Page 40: ...31 01 96 Copyright TEL...
Page 62: ...31 01 96 Copyright TEL...
Page 68: ...31 01 96 Copyright TEL...
Page 70: ...31 01 96 Copyright TEL...
Page 84: ...31 01 96 Copyright TEL...
Page 88: ...31 01 96 Copyright TEL...
Page 94: ...31 01 96 Copyright TEL...
Page 98: ...31 01 96 Copyright TEL...
Page 108: ...31 01 96 Copyright TEL...
Page 110: ...31 01 96 Copyright TEL...
Page 116: ...31 01 96 Copyright TEL...
Page 118: ...31 01 96 Copyright TEL...
Page 140: ...31 01 96 Copyright TEL...
Page 142: ...31 01 96 Copyright TEL...
Page 148: ...31 01 96 Copyright TEL...
Page 160: ...31 01 96 Copyright TEL...
Page 162: ...31 01 96 Copyright TEL...
Page 166: ...31 01 96 Copyright TEL...
Page 172: ...31 01 96 Copyright TEL...
Page 180: ...31 01 96 Copyright TEL...
Page 190: ...31 01 96 Copyright TEL...
Page 192: ...31 01 96 Copyright TEL...
Page 196: ...31 01 96 Copyright TEL 1 3 Versions Description Version 10 136 174MHz...
Page 198: ...31 01 96 Copyright TEL...
Page 204: ...31 01 96 Copyright TEL...
Page 212: ...31 01 96 Copyright TEL...
Page 218: ...31 01 96 Copyright TEL...
Page 220: ...31 01 96 Copyright TEL...
Page 222: ...31 01 96 Copyright TEL...
Page 224: ...31 01 96 Copyright TEL...
Page 228: ...31 01 96 Copyright TEL...
Page 232: ...31 01 96 Copyright TEL...
Page 236: ...31 01 96 Copyright TEL...
Page 238: ...31 01 96 Copyright TEL...
Page 240: ...31 01 96 Copyright TEL...
Page 243: ...T800 Memory PCB IPN 220 01144 00 Top Side Copyright TEL 31 01 96...
Page 244: ...31 01 96 Copyright TEL T800 Memory PCB IPN 220 01144 00 Bottom Side...
Page 246: ...E2 6 T800 Memory PCB Information M830 00 31 01 96 Copyright TEL...
Page 250: ...31 01 96 Copyright TEL...
Page 251: ...T830 VCO PCB IPN 220 01176 01 Bottom Side Copyright TEL 31 01 96...
Page 252: ...31 01 96 Copyright TEL T830 VCO PCB IPN 220 01176 01 Top Side...
Page 253: ...M830 00 T830 VCO PCB Information E3 7 Copyright TEL 31 01 96 T830 VCO 220 01176 01...
Page 254: ...E3 8 T830 VCO PCB Information M830 00 31 01 96 Copyright TEL...
Page 256: ...31 01 96 Copyright TEL...
Page 260: ...31 01 96 Copyright TEL...
Page 264: ...31 01 96 Copyright TEL...
Page 272: ...31 01 96 Copyright TEL...
Page 278: ...31 01 96 Copyright TEL...
Page 284: ...31 01 96 Copyright TEL...