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  MTR2000 Rear-of-station
(backplane) Connectors

Compiled by Robert W. Meister WA1MIK
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Here's a graphical identification of the various connectors.

bp1.jpg

Here's an actual photograph with pin numbers added. Click on it for a larger view.

bp2.jpg

The following connectors are located on the front (card-cage side) of the backplane and their designation runs from top to bottom. They are referenced by the tables below but are not detailed further.

The following connectors are located on the back of the station. An asterisk (*) at the end of any signal name in these tables denotes active-low. Notes are indicated as a digit within square brackets [n] and appear at the end of these tables.

Motorola sells a generic System Cable Kit, part number TKN9205A for these stations. This cable provides a housing shell that plugs into the 96-pin backplane connector, 30 loose pins, and a quantity of 24 gauge wires with a pin for the header crimped onto one end.

Notice the screw (in the photo above) holding the cable clamp just below the connector? It's centered exactly on J5 between pin columns 16 and 17. This makes a convenient starting point if you're counting pin numbers when testing the station.

J5 System Connector Row A (lower):

Pin #Pin AssignmentI/OTo / FromSignal Characteristics
A1GPO_8 (WCO)OJ1-C32, J2-C32OCO, 100mA, 40V
A2PA Fail (Aux I/O)OJ1-C31, J2-C31OCO, 100mA, 40V, active low
A3SCI_CLCK1OJ1-C30, J2-C30, J3-C28Do not use.
A4AC FailOP8-5, J1-C29, J2-C29, J3-C24TTL output, active high
A5GPI_3 (WCI)IJ1-C28, J2-C28Pulled up transistor input, 16V max
A6GP1_15 () (NS)IJ1-C27, J2-C27Negative side opto-isolated input, see C7
A7Ext Failsoft (Aux I/O)IJ1-C26, J2-C26Pulled up transistor input, 16V max
A8GPI_1 (NS)IJ1-C25, J2-C25Pulled up transistor input, 16V max
A9GPI_2 (NS)IJ1-C24, J2-C24Pulled up transistor input, 16V max
A10VSWR_Fail* (Aux I/O)OJ1-C23, J2-C23Pulled up transistor output (10kohms to +5Vdc), active low
A11GPO_2 (WCO)OJ1-C22, J2-C22Pulled up transistor output (10kohms to +5Vdc)
A12GPO_0 (WCO)OJ1-B25, J2-B25Pulled up transistor output (10kohms to +5Vdc)
A13Antenna RelayOJ10-1, J3-C26OCO, 200mA, active low
A14Not SupportedOJ1-C18, J2-C18, J3-C19 
A15Spare 310 
A16Spare 308 
A17Aux TX AudioIJ1-C16, J2-C16, J3-C16RSS programmable input sensitivity
A18Control 14.2 VDCOP8 pins 3, 4 (via F2)+14.2Vdc [1]
A19GNDStation ground 
A205 VDCOP8 pins 7, 8+5.1 0.25 Vdc
A21Not SupportedOJ3-C12 
A22GP1_7 (WCI)IJ1-C11, J2-C11Pulled up transistor input, 16V max.
A23Spare 323 
A24Spare 320 
A25Spare 903 
A26Ext PTT or GP1_14 (), [2]IJ1-C7, J2-C7Negative side opto-isolated input, see A29
A27GNDStation ground 
A28GPI_9 (WCI) or GPO_3 (NS)I/OJ1-C6, J2-C6Caution: See Auxiliary I/O section for jumpering information
A29Ext PTT or GPI_14 (+), [2]IJ1-C5, J2-C5Positive side opto-isolated input, see A26
A30AC Fail or GPO_14, [3]OJ1-C4, J2-C4One side of normally open relay, see B29
A31GNDStation ground 
A32Control 14.2 VDCOP8 pins 3, 4 (via F2)+14.2Vdc, [1]

J5 System Connector Row B (middle):

Pin #Pin AssignmentI/OTo / FromSignal Characteristics
B1RX Lock (Aux I/O)OJ1-B32, J2-B32OCO, 100mA, 40V, active high
B2GPO_13 (WCO)OJ1-B31, J2-B31OCO, 100mA, 40V
B3RdStat or GPO_15, [4]OJ1-B30, J2-B30One side of normally open relay, see C3
B4Carrier Detect SwitchOJ1-B29, J2-B29, J3-B24TTL output, active high
B5GPI_8 (NS)IJ1-B28, J2-B28Pulled up transistor input, 16V max
B6GPI_5 (NS)IJ1-B27, J2-B27Pulled up transistor input, 16V max
B7Ext Repeat* (Aux I/O)IJ1-B26, J2-B26Pulled up transistor input, 16V max
B8Trunk Duplex Enable*IJ3-B25TTL input
B9GPI_13 (WCI) or GPO_7 (NS)I/OJ1-B24, J2-B24 Caution: See Auxiliary I/O section for jumpering information
B10Spare 311N/C 
B11GPI_12 (WCI) or GPO_6 (NS)I/OJ1-B22, J2-B22 Caution: See Auxiliary I/O section for jumpering information
B12GPI_11 (WCI) or GPO_5 (NS)I/OJ1-B23, J2-B23 
B13Spare 301N/C 
B14Not SupportedIJ1-B19, J2-B19, J3-B19TTL input
B15GNDStation ground 
B16Spare 300 
B17Spare 321 
B18Control 14.2 VDCOP8 pins 3, 4 (via F2)+14.2Vdc [1]
B19GNDStation ground 
B205 VDCOP8 pins 7, 8+5.1 0.25 Vdc
B21RdStat or GPO_15, [4]OJ1-B12OCO, 100mA, 40V
B22Spare 322 
B23Spare 325 
B24Spare 309 
B25Spare 902 
B26Ext PTT or GPI_14, [2]IJ1-B7, J2-B7Pulled up transistor input, 16V max, see A29
B27GNDStation ground 
B28Line 4+OJ4-C10Wire line output balanced, (+)
B29AC Fail or GPO_14, [3]OJ1-B4, J2-B4Other side of normally open relay, see A30
B30Line 4OJ4-A9Wire line output balanced, ()
B31GNDStation ground 
B32Control 14.2 VDCOP8 pins 3, 4 (via F2)+14.2Vdc, [1]

J5 System Connector Row C (upper):

Pin #Pin AssignmentI/OTo / FromSignal Characteristics
C1TX Lock (Aux I/O)OJ1-A32, J2-A32OCO, 100mA, 40V, active high
C2Rdstat-R2 ControlOJ1-A31, J2-A31, J3-A26TTL output, high when unsquelched
C3RdStat or GPO_15, [4]OJ1-A30, J2-A30Other side of normally open relay, see B3
C4Failsoft Output (Aux I/O)OJ1-A29, J2-A29OCO, 100mA, 40V, active low
C5GPI_4 (WCI)IJ1-A28, J2-A28Pulled up transistor input, 16V max
C6Rx InhibitIJ1-A27, J2-A27, J3-B26TTL input, active low
C7GPI_15 (+) (NS)IJ1-A26, J2-A26Positive side opto-isolated input, see A6
C8Trunk TX Inhibit*IJ3-A25TTL input
C9RF Relay Ctrl Out (Aux I/O)OJ1-B5, J2-B5OCO, 200mA, 40V, active high
C10Ext PTT* Out (Aux I/O), [5]IJ1-A23, J2-A23, J3-A23 TTL input
C11RSSIOJ1-A22, J2-A22, J3-A22Typically 0.5Vdc for -120dBm to 3.5 Vdc for -40 dBm carrier. [6]
C12GPI_10 (WCI) or GPO_4 (NS)I/OJ1-A24, J2-A24 Caution: See Auxiliary I/O section for jumpering information
C13Spare 304 
C14Not SupportedOJ1-A19, J2-A19, J3-A19 
C15GNDStation ground 
C16GNDStation ground 
C17Disc RX AudioOJ1-A16, J2-A16, J3-A16Discriminator audio, flat response. 80mV to 400mV for 60% deviation
C18Control 14.2 VDCOP8 pins 3, 4 (via F2)+14.2Vdc [1]
C19GNDStation ground 
C205 VDCOP8 pins 7, 8+5.1 0.25 Vdc
C21Not SupportedOJ3-A12 
C22Spare 302 
C23Spare 324 
C24GPIO_0 (CNTR I/O)I/OJ1-A9, J2-A9, J3-A17TTL input/output
C25Spare 317 
C26Spare 901 
C27GNDStation ground 
C28Line 3+IJ4-C12Wire line input balanced, (+)
C29GPIO_1 (CNTR I/O)I/OJ1-A4, J2-A4, J3-A13TTL input/output
C30Line 3IJ4-A11Wire line input balanced, ()
C31GNDStation ground 
C32Control 14.2 VDCOP8 pins 3, 4 (via F2)+14.2Vdc, [1]

NOTES for the above tables:

  1. For dc-only 250W power supplies, this voltage is equal to the input supply voltage.
  2. This pin can be jumpered for Ext PTT (supported) or GPI_14 (not supported). See Aux I/O jumpers P2 and P9.
  3. This pin can be jumpered for AC Fail (supported) or GPO_14 (not supported). See Aux I/O jumper P5.
  4. This pin can be jumpered for RdStat (supported) or GPO_15 (supported). See Aux I/O jumpers P3 and P4.
  5. Ext PTT signal output, taken from Ext PTT input. The output signal can be inverted, depending on jumper settings. See jumpers P2, P6, P9.
  6. RSSI variation with carrier level is approximately 40mV/dBm.
  7. Fuses F1 and F2 (both 5A) are located behind the plate that latches the connector into J5, just below J10.
  8. In the Signal Characteristics column, "OCO" stands for Open Collector Output, "WCI" stands for Wild Card Input, and "WCO" stands for Wild Card Output.

Commonly Used Signals on J5:

The Ext. PTT Input inhibits the internal Tx PL/DPL signal. All audio, including PL/DPL, must come from another (external) source.

NameDescriptionPin #Signal Characteristics
RdStatTTL compatible logic output indicating Rx. Activation status. B3, B21, C2, C30.0 to 0.2Vdc with squelched receiver, 4.8 to 5.2Vdc with un-squelched receiver.
Disc. Rx. AudioUnfiltered and un-squelched discriminator audio without de-emphasis.C1780mV minimum to 400mV maximum for 60% system deviation. Output level is RSS programmable.
RSSIDC output volts related to received carrier level.C11 Typically 0.5Vdc for -120dBm to 3.5 Vdc for -40 dBm carrier. Variation with carrier level @ approximately 40mV/dBm.
Cntrl 14.2V14.2 volts dc output. For dc-only 250W power supplies, this voltage is equal to the input supply voltage.A18, B18, C18, A32, B32, C32 Total current through all of these pins should not exceed 1Amp.
5 V5.1 0.25 volts dc output.A20, B20, C20Total current through all of these pins should not exceed 500 mA.
GNDGround.A19, B19, C19, A27, B27, C27, A31, B31, C31 Total current through all of these pins should not exceed 1.5 Amp.
Aux.Tx AudioTx. modulation input from external source.A17 RSS programmable sensitivity. For R03.01 (host software) and earlier, the fixed sensitivity is @ 172 mVrms for 60% system deviation. RSS programmable for pre-emphasized or flat response. DC offset +2.4V. High impedance input.
Ext. PTTExternal Tx. keying signal.C10Grounding Ext. PTT pin causes Tx to key. 5.0Vdc on pin when Tx is not keyed. Note: To transmit signaling code (PL / DPL) by external PTT, it should be mapped (via RSS) to Wire line, and external modulation input should be routed to wire line.
AC_FailLogic output to indicate failure of AC line input.A4 Requires a Battery Revert dc supply. Line goes high (5.0Vdc) if AC fails.
Wire line Pair 3+/Additional wire line for other functions. C28, C30Line sensitivity and operation identical to line pairs 1 and 2.
Wire line Pair 4+/Additional wire line for other functions. B28, B30Line sensitivity and operation identical to line pairs 1 and 2

J6 Wire Line Terminals 1-4:

In the photo of the backplane, the wire line connector on my station is shown pushed up at an angle. It shouldn't be that way; it should come straight out at right angles to the backplane. I have fixed this.

The connector is meant to accept solid wire or stranded wire that's been twisted and tinned. The wires get inserted into the round holes. To release the wires, insert a round tool, a small nail, or another wire into the rectangular hole above the wire. Motorola also sells a Wireline Connector Tool just for this purpose: p/n 6600809D00.

Pin #SignalUsage and Other Notes
1Line 1-Tx wire line input for 4-wire configuration.
Input level is programmable by RSS between 0 dBm and 50 dBm.
Do NOT use this line pair for 2-wire wire line configuration.
2Line 1+
3Line 2-Rx wire line output for 4-wire configuration.
Output level is programmable between +7 dBm and 20 dBm for 100% deviation.
Use this line pair for 2-wire wire line configuration.
4Line 2+

J7 6809/MRTI Connector Pins 1-25:

More information is needed on the MRTI connector signals. The DCV and Notes were obtained by experimenting with a 100w UHF station configured as a repeater with MRTI Enabled.

The various audio signals have a frequency response of about 300 to 3000 Hz, i.e. they won't pass PL/DPL. If specified in the radio's personality, PL/DPL is transmitted along with MRTI Tx Audio when MRTI PTT is grounded.

Remember to use a DC blocking capacitor (10-100uF, 16V) on any audio signal that has DC voltage on it.

If anyone has additional information regarding the signals on the MRTI connector, please pass it on to the author.

Pin #Signal NameDCVNotes
1MRTI Tx Audio2.4Pre-emphasized, 0.4V/kHz at 1 kHz
2Trunk MRTI PTT*5.1Ground for Tx (same as pin 11)
3Spare  
4MRTI Monitor*5.1Ground probably disables Rx coded squelch
5Spare  
6Spare  
7MRTI Rx Audio2.4De-emphasized and limited to 3 kHz
8Patch Inhibit* or RSTAT5.1(same as pin 25)
9GND0.0 
10Aux Carrier* or TSTAT5.1Low when Tx is on (same as pin 12)
11Trunk MRTI PTT*5.1Ground for Tx (same as pin 2)
12Aux Carrier* or TSTAT5.1Low when Tx is on (same as pin 10)
13Trunk Tx Data+3.9 
14Spare  
15MRTI Rx Carrier*O.C.Goes to ground with properly coded carrier
16GND0.0 
17GND0.0 
18GND0.0 
19GND0.0 
20Spare  
21Trunk Tx Data-0.0 
22Trunk Rx Audio4.8De-emphasized and limited to 1 kHz
23Trunk Mute*5.1 
24PL Strip* or CCI*5.1Ground disables coded Tx
25Patch Inhibit* or RSTAT5.1(same as pin 8)
NOTE: O.C. = Open Collector, active-low.

P7 Power Amplifier Interface Pins 1-10:

Orientation looking into the rear of the station:

1   2
3   4 
5   6
7   8
9  10

Pin #Pin Assignment
1Voltage Forward
2PA Enable*
3PA Reset
4V Control
5GND
6PA D/A CS*
7SPI CLK
8MOSI
9MISO
10PA A/D CS*

J8 Backplane Power Pins 1-8:

This goes directly to the 8-pin connector on the power supply. Orientation looking into the rear of the station:

4   8
3   7
2   6
1   5

Pin #Pin AssignmentColor
1GNDBLACK
2GNDBLACK
3+14.2 VDCGRAY
4+14.2 VDCGRAY
5+5 VDCOR/WH
6+5 VDCOR/WH
7GNDBLACK
8AC FailBROWN

J10 Antenna Relay Pins 1-3:

Orientation looking into the rear of the station:

1   2   3
The external antenna relay connects to pins 1(-) and 3(+).
PTemp+ rests at +4.95 VDC.

Pin #Pin Assignment
1Antenna Relay*
2PTemp+
3+14.2 VDC

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

While not part of the backplane, this connector feeds DC power to the RF power amplifier and is visible from the back of the station. It is documented here for completeness.

UHF 100 Watt PA Power Connector Pins 1-6:

This goes directly to the 6-pin connector on the power supply. The 40w PAs operate from 14.2 VDC only. Orientation looking from the rear of the station:

3   6
2   5
1   4

Pin #Pin AssignmentColor
1+14.2 VDCBLUE
2GroundBLACK
3+28.6 VDCRED
4+14.2 VDCBLUE
5GroundBLACK
6+28.6 VDCRED

This information came from the Motorola MTR2000 Basic Service Manual, the MTR2000 Installation and Operation manual, the MTR2000 RSS Help screens and files, and the MTR3000 Basic Service Manual. Additional information, such as wire colors, came from direct examination of a 100w UHF MTR2000 station.

The author can be contacted at: his-callsign [ at ] comcast [ dot ] net.

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This page originally posted on 08-Jun-2011


Article text, photos, and hand-coded HTML © Copyright 2011 by Robert W. Meister WA1MIK.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.