LBI-38652 Mobile Communications MDS 148-174 MHz MOBILE RADIO COMBINATION TABLE OF CONTENTS MAIN BOARD ASSEMBLY . . . . FRONT PANEL ASSEMBLY . . . . POWER AMPLIFIER ASSEMBLY SERVICE SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LBI-38756 LBI-38757 LBI-38758 LBI-38759 Printed in U.S.A.
LBI-38652 LBI-38652 SPECIFICATIONS TABLE OF CONTENTS GENERAL Page Frequency Range Transmit: 148-174 MHz Receive: Same as Transmit 2 Channel Spacing 25 kHz OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Frequency Stability ±5.0 ppm INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Operating Temperature Range -30 to +60°C RADIO DESCRIPTION . . . . .
LBI-38652 LBI-38652 SPECIFICATIONS (Cont.) Spurious Emissions Radiated Conducted Meets FCC requirements -57 dBm maximum Rx Spurious Response 70 dB minimum Adj Ch(2-Sig) Selectivity -75 dB max @ 30 kHz (EIA) Intermodulation Attenuation -75 dB minimum Rx Modulation Acceptance ± 7 kHz minimum Audio Distortion 2% maximum @ 0.
LBI-38652 LBI-38652 Figure 1 - MDS Conventional Radio Block Diagram 3
LBI-38652 Receiver The RF front end of the receiver includes the PIN diode T/R switch, the tuned bandpass preselector filters, and the low noise RF amplifier. The filters have a 12 MHz bandwidth, and are factory tuned for receiving in the 150-162 MHz bandwidth. Refer to the Service Section LBI-38759 for retuning to a different frequency. The first mixer (with its low side injection from the VCO) generates a 45.000 MHz IF signal which is filtered with monolithic crystal filters having a 15 kHz bandwidth.
LBI-38652 LBI-38652 ceived and optionally de modulated by the repeater as part of the system protocol when so installed. EXTERNAL SPEAKER (Optional) Receive-Only Operation The power connector provides a place to connect an external speaker. The internal speaker must be disconnected when an external speaker is used. Channels can be programmed to receive-only operation. Channels cannot be programmed for Transmit-only operation.
LBI-38652 LBI-38652 In the Type 99 Monitor Mode the receive audio remains unmuted permitting the user to monitor all activity on the channel. When the user’s own Type 99 tones are decoded, a beep sounds and an "A" will be displayed, calling his attention to his own call now on the channel. Table 3 - Tone Groups Toggling the RESET button allows the user to choose either the Type 99 Select Mode or Type 99 Monitor Mode of receiving. The second tone group is A.
LBI-38652 LBI-38652 NOTE Group Call code numbers range from 00 to 99. However, there are several Group Calls with the same Tone B frequency. This limits the total number of Group Calls to 40. Example 1 - Group Call Code 07 (also code 27 and 37): The digit "0" in Table 5 shows that Tone B is in Tone Group 2 along with 20 to 29 and 30 to 39. Tone number 7 in Tone Group 2 is 832.5 Hz (see Table 6).
LBI-38652 8 MECHANICAL PARTS BREAKDOWN LBI-38652
LBI-38652 PARTS LIST LBI-38652 9
