The Maratrac and Radius M400 Mobiles

General Information

The Radius M400 is actually NOT the same radio as the Maratrac. Although they do use the same software, the VCO boards are physically different. The Radius M400 uses a MaxTrac / Radius type VCO board, whereas the Maratrac uses a unique VCO board specific to it. The standard Maratrac & M400 software does not allow out-of-band programming by using the SHIFT key, but the Maratrac Lab software allows direct out-of-band frequency entry.

The Radius M400 does NOT perform very well out-of-band, at least with the UHF 450-470MHz model that was tested. The radio was programmed both by modifying the .OVL file of the standard software, and by using the lab software, and here were the results:

Something in the Radius M400 does not allow the PA to operate outside the specified band limits of 450-470. This appears to be a firmware or software limitation. When the radio was programmed, it received beautifully in the ham band, but put only milliwatts of power out. The Maratrac on the other hand has no problems operating in the amateur band as we've been told. The M400 is a suitable radio for use in the 450-470MHz band, but it IS internally different than the Maratrac.

The M400 Programming Port is the same as a standard Maxtrac / Radius Mic Jack. You can plug in a Radius microphone and use it to key the radio, talk on the radio, etc, it's the SAME THING.

Check out the programming cable. Now, don't email us asking why this is the cable since you can't find anywhere to plug it in to. You may have to pop the lid on the transceiver and there is a jack on the front interconnect board where you plug in programming cable, click here to see where.

The 16 channel and the 8 channel clamshell head are electrically the same. The only difference is the label and what the switch label says. All you have to do is change it to clamshell with scan in the RSS and program the scan list and also the hang-up box, if used, has to go between pins 24/27 not 27/30.

You can find the pinout of the control head cable here.

The pinout of the VIP connector on the A7 head should be something like this:

Pins 4, 5, 20, 21, 37, 38 go to the Siren Interface

Pin 4  = Mic High
Pin 5  = Analog Ground
Pin 20 = PTT In
Pin 21 = Digital Ground
Pin 37 = PTT Out
Pin 38 = On/Off

Pin 35 = Hub 
Pin 36 = Hub Ref

Pin 19 = Emergency Ref
Pin 3  = Emergency

Pin 2  = Horn Relay
Pin 34 = Light Relay

Pin 1  = VIP Out

Pin 18 = B+

The siren for the Maratrac can be used in a stand-alone application, you do need the DEK (direct entry keyboard) with the control buttons in order to use it though.

If you have a low band Maratrac and want to figure out which split it is (without reading it with RSS), then open up the radio and look at which RF board is installed:

The part number for the Maratrac DTMF microphone is HMN1022 (for an A7 head).

There is an advanced head for a Maratrac that has a squelch knob on it, yes it is factory. The audio/squelch board is different on the radios that support the squelch control. Drawers with a HLN5342ESP01 audio/squelch board can use the head mounted squelch control, older ones will not. You can view the board component layout as well as the schematic diagram of the HLN5342ESP01 audio/squelch board. The rest of the schematic can be found in your Maratrac Service Manual, this is the only important part with the comparator circuit used for the squelch knob.

Accessory/Option Connector

The M400 also has a Radius style 16 Pin Accessory connector inside it. This connector pinout is NOT the same as a normal Raduis. See below.

** - The terms IN and OUT here refer to audio going IN to and OUT of the option board. If you're not doing any audio processing, make sure that JU1501 is in the IN position.

The pin numbering is here.

The only signal conspicuously absent from J22 is COR/COS, but never fear... It's available on the adjacent Audio Board connector, J21. By soldering a jumper between pins 11 and 13 of J21, you can make the SQUELCH_DECISION (read: COS) signal, appear at J22-12, the spare line. This is an active low that can provide COS to your controller or other equipment. Now, all the commonly desired signals are available on the easily accessible Option Connector.

If ignition control is needed with the advanced head Maratrac (99 channel), jumper JU1003 inside the control head must be clipped. If your radio has ignition control enabled from the factory, you probably have the usual orange and green wires in your harness. These will need +12V to power up the radio.

Low Band Extender Information

On many of the low band radios, they have an "extender" circuit built into the receiver.

It is really an extended noise blanker. It is standard on most low band radios made by Motorola. It is good for blocking out noise (pops and hiss) on low band.

Service Manuals

Here are a listing of the Service Manual part numbers for this series of radios:

Programming Without a Control Head

If you need to program a Maratrac, and do not have a control head available, all is not lost. What you do need is a control cable from a Maratrac, Mitrek, Mocom 70, or Motrac.

What you want to do is wire pin 17 and 13 to NEGATIVE, and pin 19 and 4 to 12VDC. This can be used to power the radio up. Then you just use the programming port in the radio to do the programming.

This power cable can also be used to power up the radio to use as a transmitter without a control head. Again, you just use the programming port to access the PTT and mic audio pins.

Adding PAC-RT Operation

If you want to add PAC-RT operation to the Maratrac you need cable part number NKN6214B which has been modified for special application SP09. Click the link to see the wiring diagram of part number NKN6214BSP09.

If you are adding PAC-RT to the Maratrac, you will need to do the following modifications:

This modification routes mobile receiver audio to the PAC-RT using the transmit LED wire. Transmit light function is disabled. These modifications are from the Motorola service bulletin and are to be used in conjunction with the above cable.

Out of Band Modifications

Open the file indicated in your hex editor (such as Hex Workshop) and apply the changes you want, you do not need to correct a checksum once your changes have been made.

The tables below show the locations in the file corresponding to each bandsplit. The first set of locations listed correspond to what is displayed in the Radio Wide Configuration screen as the bandsplit of the radio. The second set are the ones that affect what the RSS will allow you to enter and program into the radio.

Radius M400 Version 2.00 Modifications

We only have the locations for the 450-470 bandsplit.

It appears that you can program the Maratrac with Radius M400 RSS.

The modifications apply to the M400OVL2.OVL file.

Displayed bandsplit:

Hex Offset	Hex Value	Decimal Value	Frequency (MHz)

B186		9411		4500			450.0
B18D		5C12		4700			470.0

Programming bandplit:

Hex Offset	Hex Value	Decimal Value	Frequency (MHz)

DBA8		9411		4500			450.0
DBAF		5C12		4700			470.0

Radius M400 Version 2.01 and 3.00 Modifications

The modifications apply to the M400OVL2.OVL file.

Displayed bandsplit:

Hex Offset	Hex Value	Decimal Value	Frequency (MHz)

B141		2901		297			29.7
B148		6801		360			36.0

B152		6801		360			36.0
B159		A401		420			42.0

B163		A401		420			42.0
B16A		F401		500			50.0

B174		E100		225			22.5
B17B		2901		297			29.7

B185		5005		1360			136.0
B18C		1806		1560			156.0

B196		A005		1440			144.0
B19D		CC06		1740			174.0

B1A6		BE0F		4030			403.0
B1AD		CC10		4300			430.0

B1B6		9411		4500			450.0
B1BD		5C12		4700			470.0

B1C6		5C12		4700			470.0
B1CD		4C13		4940			494.0

B1D6		4C13		4940			494.0
B1DD		0014		5120			512.0

Programming bandsplit:

Hex Offset	Hex Value	Decimal Value	Frequency (MHz)

DD9D		2901		297			29.7
DDA4		6801		360			36.0

DDAE		6801		360			36.0
DDB5		AE01		430			43.0

DDBF		A401		420			42.0
DDC6		F401		500			50.0

DDD0		E100		225			22.5
DDD7		2901		297			29.7

DDE1		5005		1360			136.0
DDE8		1806		1560			156.0

DDF2		A005		1440			144.0
DDF9		CC06		1740			174.0

DE02		BE0F		4030			403.0
DE09		CC10		4300			430.0

DE12		9411		4500			450.0
DE19		5C12		4700			470.0

DE22		5C12		4700			470.0
DE29		4C13		4940			494.0

DE32		4C13		4940			494.0
DE39		0014		5120			512.0

Maratrac Version 4.02 and 4.03 Modifications

The modifications apply to the MARATRC2.OVL file.

Displayed bandsplit:

Hex Offset	Hex Value	Decimal Value	Frequency (MHz)

1708D		2901		297			29.7
17094		6801		360			36.0

1709E		6801		360			36.0
170A5		A401		420			42.0

170AF		A401		420			42.0
170B6		F401		500			50.0

170C0		E100		225			22.5
170C7		2901		297			29.7

170D1		5005		1360			136.0
170D8		1806		1560			156.0

170E2		A005		1440			144.0
170E9		CC06		1740			174.0

170F2		BE0F		4030			403.0
170F9		CC10		4300			430.0

17102		9411		4500			450.0
17109		5C12		4700			470.0

17112		5C12		4700			470.0
17119		4C13		4940			494.0

17122		4C13		4940			494.0
17129		0014		5120			512.0

Programming bandsplit:

Hex Offset	Hex Value	Decimal Value	Frequency (MHz)

19B17		2901		297			29.7
19B1E		6801		360			36.0

19B28		6801		360			36.0
19B2F		AE01		430			43.0

19B39		A401		420			42.0
19B40		F401		500			50.0

19B4A		E100		225			22.5
19B51		2901		297			29.7

19B5B		5005		1360			136.0
19B62		1806		1560			156.0

19B6C		A005		1440			144.0
19B73		CC06		1740			174.0

19B7C		BE0F		4030			403.0
19B83		CC10		4300			430.0

19B8C		9411		4500			450.0
19B93		5C12		4700			470.0

19B9C		5C12		4700			470.0
19BA3		4C13		4940			494.0

19BAC		4C13		4940			494.0
19BB3		0014		5120			512.0

Now that you know what locations you have to change, you need to figure out what to put in. It is fairly simple to figure out, you can use either the Base Converter in Hex Workshop, or any ordinary calculator that can do DEC-to-HEX conversions.

For example, if you wanted to change the low end of the 450-470 bandsplit radio from 450 to 440... as you can see from the above pattern, you will need to convert 4400 from decimal to hex. When you do this you should get 1130. All you have to do is swap the high and low order bytes and you get 3011.

This is the number you would replace the 9411 with and there you have it, your radio will now be able to be programmed from 440-470. Note however, that just because you can program the frequencies into the radio, it doesn't mean that the radio will work well there, if at all.

Modifications for Effective 6meter Use

Some information regarding moving the Maratrac out of band (50 to 54 mhz):

The Maratrac is a real bear to modify for amateur use. Its front end is designed for 42 to 50, and that's about it. Above 50, it rolls off very steep and is useless in the FM portion of the band. Also neither the transmit or receive VCOs will lock reliably much above 51 so you'll need to change out the coils (available from Digikey). Fortunately, the injection oscillator, exciter, and power amplifier are pretty flat and you won't need to make any changes there. The one nice thing is that the only physical modifications that are needed are all on the RF board. You don't have to hack the radio apart. You can install a stock RF board and return the radio to stock condition. With the modified board, your radio will now operate from about 46 to 54 MHz and you'll lose the 42 to 46 MHz sensitivity (if you can lock the VCOs)

In addition to the VCO coils, you'll need to make extensive modifications to the RF board (like changing out 20 or so chip capacitors). Its a good idea to sweep the entire front end before making the changes to try and shift the front-end curve up by 4 MHz. When you finish, if you're lucky, the sensitivity should be about spec. (0.35uV for 12 dB SINAD).

It's a nice radio but a lot of work to convert, not to mention the need for the software that will allow you to program it out of band.

The bottom line is that, unless you like spending few bucks on parts and several nights working under a magnifying glass, stick with the crystal bound radios - this one wasn't designed for amateur use.


After programming up the radio out of band, you should be able to tune up the RF board the same way you do the low band Maxtrac using the SL point. More than 10 of these have been done using this technique and it works without a flaw. There is no need to change any parts on the board unless you want it broad-banded. Maratracs have been made to TX and RX as high as 56 MHz without loosing any power.

So, what have you got to lose? Give it a try.

Converting to 99 Channels

Converting to 99 channels is fairly straight forward. First, you need the "advanced" control head (looks like a cheap X9000 head) and control cable. The radios are the same whether they are 8, 16 or 99 channels, it is onle the control head that is different.

Then, all you have to do is power up the radio, it doesn't matter if it has the advanced or clamshell head, go into the Service Menu, and change the radio control head type to Advanced.

That's it, go back in program in your extra channels.

X9000 Head on a Maratrac

Someone in the Texas Highway Patrol uses this setup (you have to program the head with X9000 RSS and the Maratrac with Maratrac RSS). Supposedly it involves adding an interface board to the X9000 head.

We do not have much info on this, but as is comes in, it will be added.

So far, it looks like the interconnect board you need for this modification is HLN5343CSP01.

The interesting thing though is in talking to some of the tech's at DPS, they like have never seen this combination. As far as they are aware, DPS never purchased a Maratrac through HQ. So, this is probably the work of a ham or a county owned combo, as the HQ radio shops only purchased and installed VHF Syntor X9000, Spectra 9000, and Astro 9000 mobiles. We have been told positively that the 9000/Maratrac combo was not a standard installation.

In 1985 DPS bought the first of several large amounts of Syntor X9000's with integrated sirens. In 1995 they started replacing them with System 9000 Astro radios. The siren controls are integrated with the main control head (No DEK boxes).