In typical Motorola fashion, the Maxtrac and Radius line of mobiles are really the same radio! The only real difference is the actual firmware of the radio. All of the info provided here should work with varying degrees of success depending on the features of the original radio. The Service Manual is crammed full of stuff and would be well worth ordering if you plan to do any experimenting with the radio. The part number of the Service Manual is 6880102W84 for the Maxtrac and it contains info on all models of the radio (Low, VHF, UHF, and 800 MHz).
Do you need a pinout for the 16 pin accessory connector, the 5 pin accessory connector, or the mic connector, or how about the programming cable?
If you want to inject audio into your Maxtrac/Radius while tuning it up with the RSS, you will want to have a look at this schematic.
For a easy overview of all the programmable pin configurations on the accessory connector, check out this Excel Spreadsheet or this image.
If you want an easy way to connect to the Accessory Connector on these radios, you can order the HLN9242A or HLN9457A Accessory Connector kits. These include an accessory connector housing, some pins, and some wires with pins already attached. One thing to note, the HLN9242A kit also includes a pin extractor for removing previously installed pins.
If you would rather build your own accessory cables, the parts are available from DigiKey. You will want the following:
The first two parts are for a 16 pin accessory connector. The second two are for a 5 pin accessory connector.
Do you want to program frequencies outside of the normal bandsplit? For a Maxtrac look at Maxtrac, for a Radius look at Radius.
Having RSS errors? Look at the Radius Series RSS Error Codes
Some people's voices just suck when broadcast over a Maxtrac/Radius due to the the cutoff frequencies used in the TX Audio stage. Here is modification to make the audio more pleasing to the ear.
If you have a TDN8310A DTMF microphone from a Maxtrac and are looking for a schematic for it... look no further. The proper source for the schematic is in the 6880309C84 manual. However, this microphone is almost identicle to the VLN1017A DTMF microphone for the MCX1000. You can look at the Tone/Logic Board and the Microphone/Beeper Board schematics. Note that the part designations in these schematics are slightly different for the TDN8310A, but it is better than nothing. This board layout will make locating the proper jumpers a bit easier.
If you get the above mentioned 6880309C84 manual, you will find that it covers the following microphones:
Another microphone manual that may be of interest is the 6881085E15. It covers the Auto-Dial Touch Code Encoder Palm Microphones with Backlit Keypad. These are microphones:
One interesting feature of these microphones is they have an option jumper that allows the +12 volts of a Systems 9000 microphone connector to power the keypad backlight (you also need a Systems 9000 microphone cord with all 6 wires). These microphones have 9 auto-dial memories and one last number dialed memory (the manual has the programming info).
If you want to build a nice little programmer for the Maxtrac/Radius radios, one that does not require a RIB, check out this link. Just connect the BUS+ and GND wires from the circuit to the appropriate pins on the microphone connector as shown in the programming cable schematic. If you check the RIB page you will find some additional circuits you can try.
Identifying Model Variations
One thing difficult about this line of radios, it determining what radio you have in your hands without being able to read it with the appropriate RSS. This is because there is only so much information you can gain from the model number (namely band and power).
First a little bit about the model number. If you look at a typical model number, D35LRA5GB6BK, the quickest way to tell what sort of radio you have is to look at the second and third characters. They determine output power level and frequency range, respectively:
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Now, in order to narrow down the actual frequency split without reading the radio. You will have to disassemble the radio, remove the top shield on the RF board and look for the part number stamped or silk screened on the PC board. From the following chart, you should be able to determine the bandsplit of the radio:
| Part Number | Bandsplit |
| HLB4099A | 29.7-36.0MHz |
| HLB4100A | 36.0-42.0MHz |
| HLB4101A | 42.0-50.0MHz |
| HLD4321B | 136-162MHz |
| HLD4322B | 146-174MHz |
| HLE4424A(B) | 403-430MHz |
| HLE4425A(B) | 449-470MHz |
| HLE9310A(B) | 449-470MHz |
| HLF4095B | RX 851-870MHz TX 806-825MHz |
| HLF9122A | RX 851-870MHz TX 806-825MHz TX 851-870MHz |
The only thing left is to figure out which logic board you have. There are four different ones used in the Maxtrac series. The part number can be determined while you already have the radio apart, just locate the part number stamped on the logic board (bottom of the radio).
| Part Number | Description |
| HLN9313A | Full Options and Signalling Capable, 16 Pin Accessory Connector, Expanded Board |
| HLN9123A | Basic Limited Board, No Signalling, 5 Pin Accessory Connector, Limited Channels, Masked Board |
| HLN5173B | Signalling Capable, 5 Pin Accessory Connector, No External EEPROM (Limited Channels), Expanded Board |
| HLN5172A | Same as HLN9313A, Except 5 Pin Accessory Connector |
The logic boards can be found in just about any bandsplit radio. The logic board is not frequency dependent and it operation is determined by what firmware is installed in it (expanded boards), as well as what it was initialized with in the RSS.
This should give you a start on determining what radio you have in your hands. The only real way to determine the what all the options the radio is currently capable of is to read it. If you are going to be hacking on these radios, you would want to try and get one with either a 5172 or 9313 logic board in it, unless you are just building a repeater link or something.
Maxtrac/Radius Power Problems
Sometimes you may come across one of these radios which will not power up when you apply 12VDC to the power connector on the back of the radio. Well in this case, one of the first things you should check is that the radio has not been setup for Ignition Control. If it is, then the radio will not power up until you apply 12VDC to the appropriate Ignition Control pin on the Accessory Connector.
The quickest way to check to see if this is the case is to use an ohm meter and measure for continuity between the positive connection on the main power connector and Pin 5 of a 5 pin accessory connector, or Pin 10 of the 16 pin accessory connector. If you have continuity, then Ignition Control is not your problem... get out the service manual. If, on the other hand, you do not measure continuity, then read on!
You now have a choice, you can either continue to use the radio in this fashion, by getting the appropriate accessory connector for your radio and applying 12VDC to the Ignition Control pin to turn the radio on. Or, you can restore the radio to normal operation by replacing the missing component in the radio.
To restore the radio to normal operation, you will need to remove the head and bottom cover from the radio. This should expose the logic board. Now, locate the component that you are interested in, it is F801 for the 5 pin type logic board, or JU801 on the 16 pin logic boards. These devices are a 1A and 2A fuse in a 1/4W resistor type package. If the one in your radio is missing or burnt out, your radio will not power up without power applied to the accessory connector. It is quite common for the fuse to be blown when the pin on the Accessory Connector is shorted to ground. That is why when you replace or install this component, you must use the appropriate fuse, and not just a piece of wire, unless you want to replace your logic board in the future.
Once you replace this component, the radio should power up as it normally would.
Linking Maxtracs for Repeater/Crossband Use
Need to connect a couple of Maxtrac/Radius radios together? Here is a schematic of the R.I.C.K. to get you started. Order the service manual part number 6880901Z79 from Motorola.
An alternative method of linking 2 Maxtrac/Radius type radios together can be found here. DO NOT USE THIS WITH 900MHz RADIOS, the pinout of the microphone connector is different!
Trunking 800MHz Maxtracs
These are radios that usually have model numbers starting with D35 or D45.
You can convert a trunking Maxtrac or Radius back to conventional 800MHz operation. You will need to replace the trunking firmware in the radio with conventional firmware. You will then need to blank the logic board with Lab RSS, and re-initialize it as a conventional radio. Note that before changing the firmware and blanking the board, you should write down all the alignment settings in the radio.
Conventional Maxtrac's make nice receivers for receiving your local trunking system's data channel... for use in Trunker of course. If you don't know what Trunker is, you better check out Lindsay's Site. You will find that if you connect your data slicer to RX Audio (Pin 11) and Ground (Pin 7) on the Accessory Connector, you will have a nice little setup. One thing you will want to check though, is that JU551, a 3 pin jumper header on the logic board, is set to Position A. This will give you flat, unmuted audio on Pin 11 of the Accessory Connector. This is assuming of course that you are using a radio with a 16 pin Accessory Connector, otherwise, you are on your own.
If you're playing with Trunking Maxtracs and TrunkTrackers, you may be interested in this conversion spreadsheet. It is a Microsoft Excel document. It converts Motorola Talkgroup ID's to Maxtrac ID's and TrunkTracker ID's.
If you are working on tuning up a Trunked Maxtrac, here is the information on putting the radio into test mode.
900MHz Amateur Radio Conversion
The Maxtrac/Radius will work just fine in the Ham band. But, you will need to make some modifications to the RF section as well as some of the programming in order to get it to work properly.
Before you go any further, you must be trying to convert a 900MHz radio, these would be models that have model numbers starting with either D27 or D37. If you have a D35 or D45 radio, then you have an 800MHz radio, and you will not be able to convert these radios to the 900MHz band.
You can convert the trunking D27 "B2" radio, and make it into a 2 channel conventional radio.
If you want the straight forward instructions on converting the radio, then follow this link. The modifications presented there should provide sufficient results for most people.
If you are looking for an explanation on how the Pin Shift signal works and which VCO's do what, then you will want to look at the Pin Shift explained page.
If you are a die hard and want full coverage on transmit and receive, there are going to be some more modifications involved. You will want to investigate these modifications which came from Michael Roche, AA2LS.
You can also get a little help with some of the tune-up instructions if you check here.
50-54MHz (6 Meters) Amateur Radio Conversion
You've got a Maxtrac/Radius that you want to tune up on 6m... check here.
9600 Baud Packet Conversion
The Maxtrac/Radius Series are 9600 baud packet capable. They do need a minor modification though. For RX, its no big deal, just take RX audio from PIN 11 of the Accessory Connector and swing JU551 to the (A) position (Flat RX Unmuted). For TX audio, you will have to run a jumper to the junction of R223, C228, R222 on the RF board to inject the data (if applicable you may need to set the deviation pot in the radio to maximum). You might want to put a pot on your TX line somewhat like the setup Motorola uses (voltage divider) to adjust the deviation. It would be wise to do some measurements to make sure you have the deviation correct. You might also want run the RX and TX pins to the unused pins on the front mic connector after the mods are done.
Information Common to Both Maxtrac and Radius
Since these radios are so much alike, lets start with some things you can do that apply to both series of radios.
Codeplug Checksum Location
If you happen to be messing around in the codeplug file, be aware that the first 0x2D bytes need to have the proper checksum (stored at offset 0x2E).
For example, if you wanted to calculate the checksum of the following header in a codeplug file:
You would select the bytes and do a 1's Complement Hex Checksum calculation.
The Checksum-8 value is the one you want to enter into offset 0x2E. In this case you can see that they already match.
We've been told that the same applies if you are changing the serial number of the radio using the EEPROM access feature of Lab RSS. The nice feature of using the Lab RSS is that it has the option to correct the checksum for you.
Location of Model Index in Codeplug
First, lets take a look at an example from a .mdf file:
The highlighted entry contains all the info for a specific model of radio.
For the particular model selected, the index that refers to this radio is this:
Now, if you open the saved file (codeplug) for your radio, you'll see something like this at the beginning of the file:
Now, the tricky part of this is, the index isn't stored in one location. The red bytes are the index. Notice they match the index bytes you found in the .mdf file.
The significance of knowing the index number for your radio comes to when you start modifying the .mdf file for specific features in your model of radio. If you were to search for your model number in the .mdf file, you will have more than one hit, but, they each have unique index numbers...
Add Channels by Editing the .MDF File
This information is common to both the Maxtrac and Radius lines. Depending on which logic board and firmware is in your radio, this may or may not work. The example screenshots shown are for the Maxtrac version R06.01.00c RSS.
Open the MAXTRAC.MDF or RADMBL.MDF in your Hex editor, Hex Workshop is an excellent program for this. The Maxtrac and Radius RSS don't do any checksum checks of the file so you don't have to worry about correcting the checksum later.
Search for your model number in the file, you probably will come accross more than one entry so you can either change them all or use the information above to locate the proper index to change a specific model.
Once you find your model entry you should see something like this:
If you look at this model entry, the third byte after the model number (offset 0x1036) is a 0x20.
This is the hex representation for the number of channels in the radio, in this case 32 ch. Depending on your radio you might want to try changing this to 0x10, 0x20, or 0x28, or higher to give you 16, 32, and 40 channels respectively.
Also note the 0x02 at offset 0x1034, this is the bandsplit identifier for this radio and corresponds to the table entry at the top of the .mdf file.
The 0x01 at offset 0x1035 refers to the power level of the radio.
To find out if you picked the correct model number to edit, save the .mdf file and load your radio's codeplug into the RSS. Try adding channels with the Mode Utility and see what happens.
One thing you have to be careful of is that the RSS will let you put as many channels into it that you want, what the radio will accept is another thing. It appears that once you exceed the maximum number of channels for a radio and try to program them in, the firmware will "wrap" the extra data around to the beginning and start programming from channel 01. You will be able to tell if you have exceeded the maximum number of channels by trying to program in one channel at a time until it "wraps", ie. if the maximum number of channels your radio will take is 16 and you try to program 17 channels into it, once programming has finished you will find your radio will only show 1 channel. Another thing that might happen is that if you exceed the number of channels programmed into the radio, the display will show funny things as you scroll through the channels, it depends on the firmware in the radio.
.MDF File Structure
OK, we have finally figured out most of the information contained in a record in the .mdf file for the Maxtrac/Radius line.
By knowing this, we are able to do things like enable scan, signalling, etc. However, even if you enable the options by editing the .mdf file, it does not mean that they will always work, the firmware in the radio has to support the options as well.
Now, on to the structure itself. The highlighted area below indicates an individual record for a particular model Maxtrac. The Radius is essentially the same, just with different model numbers.
As you can see, this example covers a model located between offsets 0x01BB6 and 0x01BCA inclusive. The breakdown of the record is as follows:
| Offset (example) | Description |
| 0x1BB6-0x1BB7 | Model Index |
| 0x1BB8 | Displayed Model Name |
| 0x1BB9-0x1BC4 | Model Number |
| 0x1BC5 | Bandsplit Index |
| 0x1BC6 | Radio Power Level |
| 0x1BC7 | Number of Channels |
| 0x1BC8 | Displayed Power |
| 0x1BC9-0x1BCA | Radio Options |
Field descriptions:
Model Index
As can be seen elsewhere on this page, the Model Index is what actually tells the RSS what radio you are working with. It figures out the index from the codeplug in the radio or on file and locates the appropriate record in the .mdf file based on that information.
Once the RSS knows the Model Index, it can read all the specific information on what that radio is capable of by reading the rest of the model information in the .mdf file record.
Displayed Model Name
This byte determines what model name (ie. Maxtrac 300, Radius M214/216) is displayed in the RSS when you read the radio codeplug.
All the possible model names are stored at the beginning of the .mdf file. If you change this byte, the model name displayed will change. For example, this radio has a byte of 0x07. If you read this radio, it will have a name of Maxtrac 300. If you change the byte to 0x06, the name will change to Maxtrac 100.
Model Number
These bytes are the hex representation of the actual model number of the radio in question. That's about it. There are a number of radios in the Maxtrac/Radius series that have the exact same model number, but have different features or options. That is why there is no model breakdown chart for them. The only way to actually figure out the options in a particular radio is to read it.
Bandsplit Index
This byte determines which bandsplit information record is used for this radio. The bandsplit table is located just under the model names at the beginning of the .mdf file. More information on the structure of that table is available elsewhere on this page.
Radio Power Level
Not exactly sure on how this one works. It depends on what the bandsplit of the radio is and the power level (high or low).
Number of Channels
This byte is a hex representation of the number of channels in the radio. It is explained further elsewhere on this page.
Displayed Power
This byte is a hex representation of the power level of the radio. It is used to display the power level on the Radio Wide screen. By changing this byte, you will change the power field on the Radio Wide screen. It has no other effect.
Radio Options
These two bytes are some of the most important. They determine what options are enabled in the radio and are capable of being modified by the RSS. Now, just because you enable the options, it doesn't mean that your radio will support them, that depends on the firmware in the radio, as well as the codeplug in the radio. It is generally possible to upgrade the firmware in the radio, and usually will involve blanking, re-initializing, and re-tuning the radio in the process, but it is possible.
It also appears that some options need to be turned on in the codeplug of the radio, regardless of whether those bits are enabled in the .mdf file. The bytes in the radio that seem to affect these options are at offset 0x1FE and 0x1FF in a codeplug archive.
At any rate, what we have determined from the .mdf file is as follows...
Options are determined by whether a specific bit in the option bytes are turned on or off. Each of the two option bytes can be broken down into an upper nibble, and a lower nibble. When each nibble is converted to binary, you get all the possible option bits that can be changed.
In this example, our option bytes are the fairly common 0x27, 0x1C. This translates as follows:
NAME UPPER1 LOWER1 UPPER2 LOWER2
HEX 2 7 1 C
BIN 0 0 1 0 0 1 1 1 0 0 0 1 1 1 0 0
BIT# 4 3 2 1 4 3 2 1 4 3 2 1 4 3 2 1
If we look at the UPPER1 nibble, bits 1 through 4 correspond to the following options when set (1):
BIT# DESCRIPTION
1 Unknown, causes a ERROR #56 if set
2 Enables Emergency Alarm and Signalling (MDC1200/STAR/QCII/DTMF)
3 Unknown
4 Unknown
If we look at the LOWER1 nibble, bits 1 through 4 correspond to the following options when set (1):
BIT# DESCRIPTION
1 TPL/DPL/INV DPL/CSQ Squelch, Squelch field under Radio Wide set to CODED
2 TPL/DPL/INV DPL/CSQ Squelch, Squelch field under Radio Wide set to CARRIER
3 Enables Scan
4 Unknown
Note, if you do not set either bit 1 or 2 of LOWER1, then the only squelch option you are allowed in a Maxtrac is INV DPL, and in a Radius, CSQ. Normally both bits 1 and 2 are always set.
If we look at the UPPER2 nibble, bits 1 through 4 correspond to the following options when set (1):
BIT# DESCRIPTION
1 Enables Accessory Connector (if supported by radio)
2 Unknown
3 Unknown
4 Unknown
If we look at the LOWER2 nibble, bits 1 through 4 correspond to the following options when set (1):
BIT# DESCRIPTION
1 Unknown
2 Unknown
3 Affects TOT, base frequency, and signalling options, must be set
4 Enable Call List (used in conjunction with UPPER1, BIT#2
To determine what to put in the .mdf file in the option bit locations, figure out what bits you want set, convert the binary representation of the nibble to hex, and stuff it in the proper location in the .mdf. In general, if you want to enable scan and signalling (if supported by your radio), use the option bytes in this example (0x27, 0x1C).
Codeplug Hacking
Well, if you are brave enough to mess around in the codeplug using the EEPROM Access feature of the Maxtrac Lab RSS, there are some things you should know.
With version R07.02.00a Maxtrac RSS and newer, the codeplug errors you may get when reading the radio have been expanded from the usual Error #58 into a bunch of different codes. Depending on what the code is, determines the block of data in the codeplug which is corrupted. The blocks we have identified so far are as follows:
If you use the bit banger (EEPROM Edit Utility) in the RSS, you will find that the base address used is 0xB600. This is the equivalent to offset 0x0000 above.
If you use the Fix Checksum option (F6) the software will correct the checksum for first block listed (0xB600 to 0xB62D/0x000 to 0x02D).
So, if you are hacking around in the codeplug (or changing the serial number), the locations of the checksums for each block will be important.
To calculate the checksum for a block of data, you will have to enter the data into Hex Workshop (version 2.54) manually. Once the block of data is enterred, highlight all the bytes except the checksum byte and hit F12 (Calculate Checksum). Make sure the Selection, Hex, and 1's Complement options are checked off, and click Generate. The value that is generated in the Checksum-8 field is what you want to use for the checksum for the block of data when you modify it in the RSS.
MAXTRAC: Try using the "Shift method" same as with the Radius and see if your version of RSS supports it. Otherwise, well, you will either need to do some Hex editing of your saved file or get a copy of the LAB RSS.
If you are going to use the Hex editing method, see the steps below.
In the MAXTRAC.MDF file make a Checksum-16 of the whole file (the F12 option in Hex Workshop), in our case we ended up with 0x4528 (RSS V 06.00), write this down, you might need it later.
Look starting at about offset 0x2BA, you should see something like:
The highlighted area contains all the bandsplits recognized by this particular RSS.
A single bandplit entry in the table looks like:
If you look carefully at the highlighted portion, you should notice the following items>
02 00 = Bandsplit identifier (Note: it is at the end of the frequency assignments)
E4 05 = 1508 in decimal, ie 150.8000 MHz
54 06 = 1620 in decimal, ie 162.0000 MHz
Note there are 3 occurances of the strings E4 05 and 54 06, and another set of limits, 50 05 and 72 06. The first set is the limits displayed in the Radio Wide menu (F4-F2). The second set are the TX limits for the radio. The third set are the RX limits for the radio (note that if the TX and RX limits are not set the same the RX limits are screwed up). The fourth set are the limits that the radio is spec'ed to go and that Lab RSS would let you program (only giving an "Outside of FCC Limits" error), in this case the limits translate to 136.0000 MHz to 165.0000 MHz.
If you program outside these limits the Lab RSS reports that the frequencies are "Outside of FCC and Radio Bandwidth Limits". In other words, if you want to have your radio operate properly, don't exceed the limits in the "Lab" field.
To figure out what hex to enter for your bandsplits you can either use the Base Converter (in Hex Workshop), or use a calculator with a HEX --> DECIMAL conversion function.
If you are using a calculator enter your limit (ie 1360 for 136.000 MHz) and convert it to hex, you should get 0x0550. When you enter the data into the .mdf file you have to reverse the bits such that you would actually enter 0x5005 in the field you are changing.
If you are using Hex Workshop, launch the Base Converter utility and select "Intel Byte Order". Then, enter your desired frequency and write down the hex result.
You can then directly enter the hex result (0x5005) into the bandsplit field.
In this example we are changing the lower bandsplit of a 150.8-162MHz radio to 136-162MHz.
Save the new file (you might want to make a backup copy of the original if you haven't already.
Some of the RSS packages (we don't have codeplugs for everything, so we can't check them all) check the checksum of the .mdf file when you try and load a codeplug and return an error if the checksum of the .mdf file doesn't match the one stored in the program. Try running the RSS with the new .mdf file, if you don't get an error when you run the RSS and load a codeplug then you don't have to worry about the next step.
Correcting the .mdf File Checksum
If you get a corrupt .mdf file error then you will have to go back and correct the checksum in your edited .mdf file. Load the file back in your hex editor and make a Checksum-16 of the file. If you compare the new checksum
with the original one
You will find they are probably different.
The only way we have to correct the checksum of the file at this time is to keep editing bits and making Checksum-16 calculations until the edited file's checksum and the original match. You can either edit the Copyright statement or some of the model descriptions in the file. Just take one or a few of these insignificant bytes (some experimentation may be required depending on by how much the cheksum is out) and add or subtract a few bits of the numbers make a Checksum-16 of the file. You should notice the checksum has changed by the number of bits you added or subtracted. Keep going until the checksum's match.
Once the checksum's of the files match you should be able to run the RSS, load the codeplug, and enter the frequencies within your new bandsplits with ease.
Changing Band Limits in Maxtrac RSS Version 5.03
Search for F6 46 FE 01 75 03 in file MOBILE5.OVL and change the 0xF6 to 0xC6.
Search for B8 00 00 76 01 and change the 0x76 to 0xEB.
You can now program any frequency in, it is a matter if the hardware will do it.
Adding Type II/IIi Trunking to a Type I Maxtrac
First off you must start with a B5 B6 or B7 model (has to be 16 pin ACC)
The second step is to obtain a type II firmware chip for a Smartnet Maxtrac, the part number is HLN9383.
Next, you need to blank the logic board using Lab RSS.
Re-program the logic board with your trunking RSS so that it is now a Smartnet radio (either a C3, C5, or C6).
Realign the unit and you now have a unit capable of type I,II, and IIi.
Making a Maxtrac do PAC-RT
One similar way this can be economically achieved is by using a RICK unit, or building a repeater cable (see at the beginning of this page) yourself and plugging it into a second MaxTrac.
The second MaxTrac can be a simple 2-channel unit (or not) and will two-way repeat the first one and vice-versa. You can also construct this device to one-way repeat (just eliminating the second TX line) to construct a GMRS repeater out of two Maxtracs.
Otherwise, to actually use a PAC-RT with a Maxtrac you need the following cable:
MaxTrac PAC-RT Acc Conn. 3 -------------------- 6 13 -------------------- 1 11 -------------------- 21 (Shielded Cable) 2 -------------------- 19 (Shielded Cable) 7 -------------------- 8 ----- 2 | ----- 16 ----- 10 | ----- 17
Cable shields are connected to PAC-RT Pin 18 (Ground) and not connected at radio. There are two jumpers inside the PAC-RT Connector, Pin 2 to 16 (B+) and 10 to 17 (PTT Ground).
For on-off control: PAC-RT Pin 2 B+ to on/off switch Pin 9 & 15 other side of on/off switch (Pin 9 = PAC on/off, Pin 15 = Portable in/out) Both must be connected to B+ for unit to turn on, Pin 22 ground (not required, unless you want an indicator lamp, or something).
99 Channel Modification
Yes, there is a 99 channel Maxtrac. It was a SP model, low band unit that was made for Ontario Hydro in Eastern Canada. The model number is ACD51MJA9HA5AK and covers 42-50 MHz.
This radio was basically a stock low band radio, with a modified HLN9313A logic board. The logic board has a larger EEPROM installed to hold the very large codeplug as well as different (VLN5443A) firmware.
This modified radio is only able to be programmed with VVN4168A RSS. This is SP Maxtrac RSS that only supports this model.
If you are interested in the original manual supplement that covers this model, click to see page 1 and page 2.
You can convert a normal Maxtrac with the HLN9313A, 16 pin logic board, to a 99 channel model by following the instructions contained in the manual supplement. Once you expand the EEPROM and put the new firmware in, you will need to blank the logic board with Maxtrac Lab RSS and then re-initialize it with the 99 channel RSS service menu. Once you do that, you should have a radio that is capable of 99 channels, you will need to hack the .mdf file depending on what the bandsplit of the RF board is in your radio in order to be able to program the proper frequencies into it.
FYI, the firmware and RSS is NLA from Motorola. Good luck in locating it.
Panel Numbers for Lab RSS
OK, so you're hacking your poor Maxtrac with Lab RSS and have blanked the board. You are in the process of re-initializing the logic board using the Replace Logic Board options in the Service Menu. BUT, you've hit a snag... the RSS is asking you for something called a "Panel Number". What the heck is that?! Well, look no further. If you had been wise and used the built-in help (F1) when you got to this point, you would probably have found the following list, but you didn't, and now you are here.
Here are the panel numbers used when re-initializing various flavors of Maxtrac:
| Panel Number | Description |
| 0 | All 2 frequency models: Radius M100, Maxtrac50, Maxtrac100; Voice Reporter Models: H1135_, H1136_, H1138_, H1139_, H1134_ |
| 1 | All 6, 16 and 32 Frequency Models: Maxtrac 300 |
| 2 | All 6 Frequency Models with Signalling or Accessory Connector Option: Maxtrac 300 |
| 50 | Maxtrac 820 Trunked: D__MQA5GB5_K, D__MQA5GB1_K; Privacy Plus 250/750: T_5CPA5___H |
| 51 | Maxtrac 820 Trunked: D__MQA5GB3_K |
| 52 | Maxtrac 840 Trunked: D__MWA5GB5_K, D__MWA5GB6_K |
| 53 | Maxtrac 840 Trunked: D__MWA5GB7_K |
| 54 | Maxtrac 840 Trunked: D__MWA5GC0_K |
| 55 | Trunked Voice Reporter: H5011_ |
| 56 | Maxtrac 820 Trunked: D__MQA5GB4_K |
Life can be a lot easier for Radius owners. All you have to do is load your file into RSS, go the channel you want to program, when you are in the field you want to change, use the shift key and the numbers across the top of the keyboard to enter the frequency. Fill the entire field and make sure you release the shift key when you enter the decimal point. ie. 139.5500 would be !#(.%%)) Its as simple as that.
If the above method doesn't work, then you'll have to do some hex editing.
In the RADMBL.MDF file make a Checksum-16 of the whole file (the F12 option in Hex Workshop), in our case we ended up with 0xA402 (RSS V 08.00), write this down, you might need it later.
Look starting at about offset 0x29E, you should see something like:
The highlighted area contains all the bandsplits recognized by this particular RSS.
A single bandplit entry in the table looks like:
If you look carefully at the highlighted portion, you should notice the following items>
02 00 = Bandsplit identifier (Note: it is at the end of the frequency assignments)
E4 05 = 1508 in decimal, ie 150.8000 MHz
54 06 = 1620 in decimal, ie 162.0000 MHz
Note there are 3 occurances of the strings E4 05 and 54 06. The first set is the limits displayed in the Radio Wide menu (F4-F2). The second set are the TX limits for the radio. The third set are the RX limits for the radio (note that if the TX and RX limits are not set the same the RX limits are screwed up).
To figure out what hex to enter for your bandsplits you can either use the Base Converter (in Hex Workshop), or use a calculator with a HEX --> DECIMAL conversion function.
If you are using a calculator enter your limit (ie 1360 for 136.000 MHz) and convert it to hex, you should get 0x0550. When you enter the data into the .mdf file you have to reverse the bits such that you would actually enter 0x5005 in the field you are changing.
If you are using Hex Workshop, launch the Base Converter utility and select "Intel Byte Order". Then, enter your desired frequency and write down the hex result.
You can then directly enter the hex result (0x5005) into the bandsplit field.
In this example we are changing the lower bandsplit of a 150.8-162MHz radio to 136-162MHz.
Save the new file (you might want to make a backup copy of the original if you haven't already.
Some of the RSS packages (we don't have codeplugs for everything, so we can't check them all) check the checksum of the .mdf file when you try and load a codeplug and return an error if the checksum of the .mdf file doesn't match the one stored in the program. Try running the RSS with the new .mdf file, if you don't get an error when you run the RSS and load a codeplug then you don't have to worry about the next step.
Correcting the .mdf File Checksum
If you get a corrupt .mdf file error then you will have to go back and correct the checksum in your edited .mdf file. Load the file back in your hex editor and make a Checksum-16 of the file. If you compare the new checksum
with the original one
You will find they are probably different.
The only way we have to correct the checksum of the file at this time is to keep editing bits and making Checksum-16 calculations until the edited file's checksum and the original match. You can either edit the Copyright statement or some of the model descriptions in the file. Just take one or a few of these insignificant bytes (some experimentation may be required depending on by how much the cheksum is out) and add or subtract a few bits of the numbers make a Checksum-16 of the file. You should notice the checksum has changed by the number of bits you added or subtracted. Keep going until the checksum's match.
Once the checksum's of the files match you should be able to run the RSS, load the codeplug, and enter the frequencies within your new bandsplits with ease.
