Qsl radioaficionado

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Simple uni-directional and bi-directional repeater interface cables.

Figure 1 16 pin accessory connector uni-directional repeater cable diagram Figure 1 above shows the relevant circuitry as used in the Motorola RICK with respect to repeat audio. Figure 1 is for a unidirectional repeater cable and figure 2 below is for a bidirectional repeater cable. These cables are for use with 16 pinaccessory connector radios like many Maxtrac and Radius mobiles including the GM300, M10 and M120 types. A cable diagram for radios that have a 5 pin accessory connector instead is shown also. Component values are not critical. An internal jumper JU551 on the radio’s logic board should be placed in the B position. This makes squelched de-emphasized audio available at accessory pin 11. The jumperlocation is marked on the logic board. COR* is the signal that indicates that a valid signal is received, it is used to key the transmitter when it goes low (*). If the accessory connector pins are programmable, then pin 8 (COR*) should be programmed for “CSQ Detect” or “DPL/PL CSQ Detect” and active low (*). This is done in the Radio Wide (F2) >Other Accessory (F9) screens of the Radio Service Software.Some models like the 8 channel GM300, M10 and M120 don't have programmable pins and default to COR* for pin 8. The Emergency pin 9 should be disabled or programmed active low when no jumper is used between pin 7 and 9. Copyright © Wijnand Romijn 2005. Few rights reserved. Page 1 of 5

The repeat audio gain control in the cable should be adjusted for equal repeated audio when compared to theinput audio or 3 dB higher. Make this adjustment while not driving the audio into limiting. Preferably some level around half the maximum deviation. Setting the repeat audio 3 dB higher produces a bit of gain to the voice audio. Many Motorola repeaters provide this option. It helps in producing more equal audio from the repeater with different user input voice levels.

Figure 2 Mic jack dummy plugThe dummy plug with pins 3 and 4 jumpered as pictured in figure 2 should be inserted in the RX radio’s mic connector. This causes the RX radio's local speaker to open with the correct PL only. Without it, the local speaker audio will open for all received signals. This does not effect repeater operation; the repeater COR is only determined by the programmed settings. Pressing the MON button willnot place the repeater audio in the CSQ mode. Make sure to set the timeout timer in the TX radio to something reasonable. The timeout timer is a government requirement that may prevent the transmitter from staying on the air in case of a system failure. With some radio models when the RX radio is turned off, the COR line will go low causing the transmitting radio to key up. The timeout timer turnsof the transmitter when this happens. The 8 channel GM300, M10 and M120 models will not cause this problem because of their open collector COR circuit. It is important that both receiving and transmitting radios are well grounded to the same source. Preferably connect a heavy cable between both radio’s power ground connections. Alternatively, make sure both frames are well connected together.This prevents the TX radio's ground from floating up with respect to the RX radio's ground when the TX radio transmits and draws a high current. Do not depend on a connection between both radios accessory connectors pins 7 to supply this function. This pin can not handle high currents and is only grounded with a small circuit board trace in some radio models. Figure 3 below shows the cable for abi-directional repeater. This cable is identical to the uni-directional repeater cable other than that the circuitry is implemented both ways. All settings and adjustment now apply to both radios.

Copyright © Wijnand Romijn 2005. Few rights reserved. Page 2 of 5

Radio A accessory connector COR* 8 RX Audio 11

Radio B accessory connector 3 PTT*

2 Mic Seaker 15 jumper 16 PTT* 3 7 Gnd 8...
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