Spectra Mobile Radio Command Board Flat (PA) Cables

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Command Board
Flat (PA) Cables
By Robert W. Meister WA1MIK

The flat cable that plugs into the rear of the command board carries signals to the PA in all cases, but it also carries signals to the DA-15F accessory jack on those radios that have one mounted on the heat sink. The low and mid power radios have a DA-15F accessory jack mounted on the Power Amplifier (PA) heat sink. The high power radios do not. The wiring diagram for this cable is available here.

The low and mid power cable layout and folding diagram is available here. There is no documentation anywhere for the high power radio cable, unfortunately. Item 22 in this image from the VHF Basic Service Manual and the 110 watt PA diagram in the Detailed Service Manual were all I could find. This article documents the wiring of both cables.

The information below is sorted by command board pin number. The cable is standard flat wire, however the connector orientation and the way the cable is folded could affect which pin on the PA is number 1. Note that the high power PA cable utilizes only 12 conductors.

The columns below are identified as:

Signal Name: Command Board Signal Name with notes in brackets.
CmdBrd: Command Board J502 pin.
L/M PA: Low or mid power PA Board pin.
H PA: High-power PA board pin.
DA-15: DA-15F Accessory Connector pin on low or mid power PA heat sink.

Signal Name [Notes] CmdBrd L/M PA H PA DA-15

Pin on PA not used 1

V. Control Limit 1 2 1

V. Control Drive 2 3 2

(A+) Current Sense (+) 3 4 3

Keyed 9.4V 4 5 4

A+ 5 6 5

Temp Sense 6 7 6

Keyed Slot 7 8 7

Fwd Volt Detect 8 9 8

A+ 9 10 9

9.6V 10 11 10

Current Sense (-) 11 12 11

Pin on PA not used 12

Dig Gnd 12 8

Mic Hi [6] 13 15

Speaker Lo 14 7

Bus+ 15 14

Speaker Hi 16 6

Data PTT [1] 17 13

Ignition [4] 18 5

VIP Out 1 [5] 19 12

SWB+ 20 4

Det Audio [3] 21 11

VIP Out 2 [3] 22 3

Bus- 23 10

Emergency 24 2

Busy [2] 25 9

TX Audio 26 1

Command Board Signal Name Notes (from the manual):
[1]: SWB+ Sense in "SP" customer applications.
[2]: Serial Bus Reset in "SP" customer applications.
[3]: Voice Inhibit in "SP" customer applications.
[4]: SWB+ in "SP" customer applications.
[5]: Data Inhibit in "SP" customer applications.
[6]: Ground or Serial Bus Reset in "SP" customer applications.

Signal Name [Notes]	CmdBrd	L/M PA	H PA	DA-15
Pin on PA not used		1
V. Control Limit	1	2	1
V. Control Drive	2	3	2
(A+) Current Sense (+)	3	4	3
Keyed 9.4V	4	5	4
A+	5	6	5
Temp Sense	6	7	6
Keyed Slot	7	8	7
Fwd Volt Detect	8	9	8
A+	9	10	9
9.6V	10	11	10
Current Sense (-)	11	12	11
Pin on PA not used			12
Dig Gnd	12			8
Mic Hi [6]	13			15
Speaker Lo	14			7
Bus+	15			14
Speaker Hi	16			6
Data PTT [1]	17			13
Ignition [4]	18			5
VIP Out 1 [5]	19			12
SWB+	20			4
Det Audio [3]	21			11
VIP Out 2 [3]	22			3
Bus-	23			10
Emergency	24			2
Busy [2]	25			9
TX Audio	26			1

Acknowledgements and Credits:

Motorola and Spectra are trademarks of Motorola, Inc.

This information was extracted from the Motorola Spectra Two-Way FM Radio Detailed Service Manual 6880102W61, Motorola VHF Spectra FM Two-Way Radio Basic Service Manual 6881070C95, Motorola UHF Spectra FM Two-Way Radio Basic Service Manual 6881071C05, Motorola 900 MHz Spectra Two-Way FM Radio Service Manual 6880101W37-O, and Motorola 900 MHz Spectra Two-Way FM Radio Service Manual 6880101W37-C.

Contact Information:

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

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This page originally written 22-Sep-13.

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.