MAXTRAC programming

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.