The Motorola MaraTrac Index page

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and M400
Index Page
Maintained by Robert Meister WA1MIK

Information and Modification Articles:

An Overview of the Motorola MaraTrac Mobile radio by Robert Meister WA1MIK and Jim Kalkowski N1GTL
The MaraTrac is like a MaxTrac on steroids. Up to 99 channels, 100-110 watts, remote-mount. This article shows what's inside a UHF unit and a low-band unit. The Radius M400 is identical to the MaraTrac.

Activating the MaraTrac Remote Squelch Pot by Robert Meister WA1MIK
It seems many of these low-band radios come equipped with the remote squelch pot, but the radio doesn't know it's there. This article shows what seems to be the problem and how to fix it.

MaraTrac Interface Signals for Repeater Use by Robert Meister WA1MIK
MaxTracs can be used as repeaters, so why not their big cousins? This article identifies the signals available in MaraTracs (More Power!) and suggests an interface method. If you're going to build a repeater, use the MaraTrac as the transmitter as it's much better suited for longer transmit time. Use a MaxTrac as the receiver because it's much easier to get a COR signal out of. You can buy pre-made cables for this configuration on a popular auction site.

MaraTrac Manual Power Control by Robert Meister WA1MIK and Dave Malicki N1OFJ
MaraTracs, like MaxTracs, are often used on frequencies slightly out of their normal ranges. They also suffer the same indeterminate transmitter output power problem. This article shows how to add a manual power control adjustment pot specifically for the MaraTrac.

MaraTrac Low Power Control by Robert Meister WA1MIK
Based on the above article, you can add a single resistor to reduce the output power if you need to run the radio on batteries when the AC power fails.

Investigating the MaraTrac Squelch Circuit By Robert Meister WA1MIK
The MaraTrac claims to have an adaptive squelch circuit that produces a longer squelch tail when the signal is noisier. A low-band radio is tested to see how this works.

How the MaraTrac Controls Transmit Power and Deviation by Robert Meister WA1MIK
This article describes why the MaxTrac radios need manual power and deviation controls. Since the MaraTrac uses an identical logic board, the same techniques apply equally well.

Ham-friendly Firmware Mods for the MaraTrac By Robert Meister WA1MIK
What to change in the firmware to deal with out-of-band operation. A follow-up to the article above. Applies to Radius and MaxTrac radios too.

How to replace the firmware and what to align for the MaraTrac By Robert Meister WA1MIK
The procedure to replace the firmware chip and what needs to be realigned when doing so. A follow-up to the article above. Applies to Radius and MaraTrac radios too.

The Motorola Control Cable Connector Virus by Robert Meister WA1MIK
While this happened to some MaraTracs, it can also happen to a lot of other remote-mount radios that have control head cables and connectors. This article tries to explain which came first: the bent pin or the bad cable connector. It shows the problem and how to fix it.

Replacing the Dallas Memory Module In the MaraTrac By Scott Withrow KC9LQV
Radios that use the Dallas NVRAM will be losing their memory when the battery goes dead. They have about a 20 year lifetime, so any radio made prior to about 1992 will have this problem and the Dallas chip will need to be replaced. This article tells you what to do about it. While aimed at the MaxTrac, the MaraTrac suffers the same ailment.

Permanently Disabling the Extender on a Low-band MaraTrac Radio By Robert Meister WA1MIK
A simple jumper disables the noise blanker. This is necessary for radios that will be used as base station or repeater receivers.

A simple mod to the MaraTrac hand mike eliminates noises and audio dropouts By Robert Meister WA1MIK
A single jumper across the PTT switch contacts keeps the mike active all the time.

Converting a MaraTrac to a 6-meter Repeater Transmitter By Robert Meister WA1MIK

Having problems (Error 5: No power to radio or RIB) when programming your MaraTrac, yet the same setup works fine with a MaxTrac, Radius, or GM300? VE3BV had exactly this situation and after three days of pulling his hair out, he unplugged his wall-wart power pack and tried a 9V battery in the RIB. Everything worked flawlessly. He then tried the wall-wart again and found about 1VAC on the DC output line. Not sure why the MaraTrac would be more sensitive to this where the other radios weren't, but it's something to keep in mind next time you get strange programming failures. Neither one of us truly believed the error message, but it was pointing right at the problem.

Manuals, Brochures, Guides, and other printed material:

MaraTrac VHF Low-Band Service Manual 6880102W95-O 10 MB PDF Donated by Eric Lemmon WB6FLY.

MaraTrac VHF Low-Band Remote Squelch Supplement FMR-1735A-1 3.7 MB PDF
Donated by Bob WA1MIK, scanned by Eric Lemmon WB6FLY. Supplement for the low-band service manual above.

MaraTrac VHF High-Band Service Manual 6880102W18-A 8.2 MB PDF Donated by Eric Lemmon WB6FLY
Covers the radios with "AK" as the last two characters.

MaraTrac VHF High-Band Service Manual 6880102W94-O 16.6 MB PDF Donated by Eric Lemmon WB6FLY
Covers the radios with "BK" as the last two characters.

Radius M400 Service Manual 6880901Z56-O 16.6 MB PDF Donated by Eric Lemmon WB6FLY
This one manual covers all three splits / ranges on low-band, 150-174 MHz VHF, and 450-470 MHz UHF models. For all intents and purposes, the M400 radio is identical to the MaraTrac but it uses a different RSS. The M400 is to the MaraTrac like the Radius is to the MaxTrac; same hardware but sold through different channels.
This manual also has Installation Instructions.

MaraTrac / M400 RSS Error Codes 41 kB PDF
Extracted from the MaraTrac / M400 RSS User's Guide by Bob WA1MIK.

An Official MaraTrac VHF Sales Brochure 1.2 MB PDF

An Official MaraTrac Accessories Brochure 90 kB PDF

An Official MaraTrac Parts Breakdown 450 kB PDF

A transcription of the Advanced Control Head (A7) Operating Manual (fold-out card) 125 kB PDF

Scans of the Hand-Held Control Head (HHCH, A5) Installation Diagram and Control Cable 185 kB PDF

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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.

	An Overview of the Motorola MaraTrac Mobile radio by Robert Meister WA1MIK and Jim Kalkowski N1GTL The MaraTrac is like a MaxTrac on steroids. Up to 99 channels, 100-110 watts, remote-mount. This article shows what's inside a UHF unit and a low-band unit. The Radius M400 is identical to the MaraTrac.
	Activating the MaraTrac Remote Squelch Pot by Robert Meister WA1MIK It seems many of these low-band radios come equipped with the remote squelch pot, but the radio doesn't know it's there. This article shows what seems to be the problem and how to fix it.
	MaraTrac Interface Signals for Repeater Use by Robert Meister WA1MIK MaxTracs can be used as repeaters, so why not their big cousins? This article identifies the signals available in MaraTracs (More Power!) and suggests an interface method. If you're going to build a repeater, use the MaraTrac as the transmitter as it's much better suited for longer transmit time. Use a MaxTrac as the receiver because it's much easier to get a COR signal out of. You can buy pre-made cables for this configuration on a popular auction site.
	MaraTrac Manual Power Control by Robert Meister WA1MIK and Dave Malicki N1OFJ MaraTracs, like MaxTracs, are often used on frequencies slightly out of their normal ranges. They also suffer the same indeterminate transmitter output power problem. This article shows how to add a manual power control adjustment pot specifically for the MaraTrac.
	MaraTrac Low Power Control by Robert Meister WA1MIK Based on the above article, you can add a single resistor to reduce the output power if you need to run the radio on batteries when the AC power fails.
	Investigating the MaraTrac Squelch Circuit By Robert Meister WA1MIK The MaraTrac claims to have an adaptive squelch circuit that produces a longer squelch tail when the signal is noisier. A low-band radio is tested to see how this works.
	How the MaraTrac Controls Transmit Power and Deviation by Robert Meister WA1MIK This article describes why the MaxTrac radios need manual power and deviation controls. Since the MaraTrac uses an identical logic board, the same techniques apply equally well.
	Ham-friendly Firmware Mods for the MaraTrac By Robert Meister WA1MIK What to change in the firmware to deal with out-of-band operation. A follow-up to the article above. Applies to Radius and MaxTrac radios too.
	How to replace the firmware and what to align for the MaraTrac By Robert Meister WA1MIK The procedure to replace the firmware chip and what needs to be realigned when doing so. A follow-up to the article above. Applies to Radius and MaraTrac radios too.
	The Motorola Control Cable Connector Virus by Robert Meister WA1MIK While this happened to some MaraTracs, it can also happen to a lot of other remote-mount radios that have control head cables and connectors. This article tries to explain which came first: the bent pin or the bad cable connector. It shows the problem and how to fix it.
	Replacing the Dallas Memory Module In the MaraTrac By Scott Withrow KC9LQV Radios that use the Dallas NVRAM will be losing their memory when the battery goes dead. They have about a 20 year lifetime, so any radio made prior to about 1992 will have this problem and the Dallas chip will need to be replaced. This article tells you what to do about it. While aimed at the MaxTrac, the MaraTrac suffers the same ailment.
	Permanently Disabling the Extender on a Low-band MaraTrac Radio By Robert Meister WA1MIK A simple jumper disables the noise blanker. This is necessary for radios that will be used as base station or repeater receivers.
	A simple mod to the MaraTrac hand mike eliminates noises and audio dropouts By Robert Meister WA1MIK A single jumper across the PTT switch contacts keeps the mike active all the time.
	Converting a MaraTrac to a 6-meter Repeater Transmitter By Robert Meister WA1MIK
	Having problems (Error 5: No power to radio or RIB) when programming your MaraTrac, yet the same setup works fine with a MaxTrac, Radius, or GM300? VE3BV had exactly this situation and after three days of pulling his hair out, he unplugged his wall-wart power pack and tried a 9V battery in the RIB. Everything worked flawlessly. He then tried the wall-wart again and found about 1VAC on the DC output line. Not sure why the MaraTrac would be more sensitive to this where the other radios weren't, but it's something to keep in mind next time you get strange programming failures. Neither one of us truly believed the error message, but it was pointing right at the problem.

	MaraTrac VHF Low-Band Service Manual 6880102W95-O 10 MB PDF Donated by Eric Lemmon WB6FLY.
	MaraTrac VHF Low-Band Remote Squelch Supplement FMR-1735A-1 3.7 MB PDF Donated by Bob WA1MIK, scanned by Eric Lemmon WB6FLY. Supplement for the low-band service manual above.
	MaraTrac VHF High-Band Service Manual 6880102W18-A 8.2 MB PDF Donated by Eric Lemmon WB6FLY Covers the radios with "AK" as the last two characters.
	MaraTrac VHF High-Band Service Manual 6880102W94-O 16.6 MB PDF Donated by Eric Lemmon WB6FLY Covers the radios with "BK" as the last two characters.
	Radius M400 Service Manual 6880901Z56-O 16.6 MB PDF Donated by Eric Lemmon WB6FLY This one manual covers all three splits / ranges on low-band, 150-174 MHz VHF, and 450-470 MHz UHF models. For all intents and purposes, the M400 radio is identical to the MaraTrac but it uses a different RSS. The M400 is to the MaraTrac like the Radius is to the MaxTrac; same hardware but sold through different channels. This manual also has Installation Instructions.
	MaraTrac / M400 RSS Error Codes 41 kB PDF Extracted from the MaraTrac / M400 RSS User's Guide by Bob WA1MIK.
	An Official MaraTrac VHF Sales Brochure 1.2 MB PDF
	An Official MaraTrac Accessories Brochure 90 kB PDF
	An Official MaraTrac Parts Breakdown 450 kB PDF
	A transcription of the Advanced Control Head (A7) Operating Manual (fold-out card) 125 kB PDF
	Scans of the Hand-Held Control Head (HHCH, A5) Installation Diagram and Control Cable 185 kB PDF