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Extending the MT1000 Low-Band Programming Software Frequency Ranges
By Robert W. Meister WA1MIK
Low-band MT1000 radios can be made to operate in the 50-54 MHz range. See the article on Repeater-Builder by Mike May. Programming the radio with these frequencies is another matter. Existing information on the web takes you through a tedious process of entering mostly correct frequency values in the 42-50 MHz range, saving the code plug to disk, hex-editing that code plug to change the frequency values to the 50-54 MHz range, then loading that code plug back into the radio. Way too difficult. I don't know why people have put up with this inconvenient procedure for so long.
A reader inquired about using this modification allow it to handle the 10-meter amateur band, so I've added that information.
The MT1000 low-band radio uses P200 programming software. The low-band version of the Radio Service Software (RSS) for the P200 limits you to three ranges: 30.0 - 36.0 MHz, 36.0 - 42.0 MHz, or 42.0 - 50.0 MHz. You can change the range to be used by pressing F4 then F9 from the main menu. When you change the range, the in-memory code plug will be cleared and you'll be starting fresh, so make sure you choose the proper range for the radio you have before you do any programming on it. Changing the range through software does not alter the physical capabilities of the radio; you must still have the proper RF board in the radio to operate on the range you select. They must match.
IMPORTANT NOTE: Apparently the MT1000 programming software (MT1000.EXE) CAN be used on some MT1000 radios, especially those that have more than six channels. The same modifications can be applied to the MT1000 software. Just search for the appropriate values and change them. There are no checksums to deal with in either the P200LB or MT1000 programs.
In other words, all low-band MT1000 with six or more channels or an LCD display should be programmed with the MT1000 RSS. All six-channel low-band radios, either P200 or MT1000 models, should be programmed with the P200LB RSS.
Before you make any changes to the program, be sure you make a backup copy of the EXE file. Some hex-editors offer to do this every time you save changes, but I find it better to make my own. Keep it in a safe place; you never know when you'll need it, and if you make any mistakes hex-editing the file, you can always retrieve the backup and start over. It's better to have a backup and not need it, than to need it and not have it.
The modifications shown here were done with P200LB.EXE, Version D03.00.01, dated 01-Jun-90. This version seems to be the one commonly available "out there" on the web.
The P200LB.EXE and MT1000.EXE programs have the same values, but they're located at different addresses. You can search for the same data bytes and change them as described in this article to achieve the same results. Also, different program versions may store these bytes in different locations, so it is safer to use your hex editor and search for the values rather than just change absolute locations.
All addresses and data bytes are in hexadecimal. Data bytes you'll be changing are shown in bold red.
Changing the Upper Band Limit for 6-meters:
The software frequency limitations are stored in two separate areas within the P200LB.EXE file. One specifies the lower limits; the other specifies the upper limits. We're only concerned with the upper limit, which restricts frequency data to 50.0 MHz. The values are stored as 8-byte, double precision, floating point values. Hex Workshop (and probably any hex editor) can find the exact location (there's only one occurrence of the double precision value 50.0). This value is stored starting at hex address 3A122:
3A122: 00 00 00 00 00 00 49 90
The above eight bytes represent a value of 50.0 decimal.
Change the byte at location 3A128 from 49 to 4B to change the upper limit to 54.0 decimal. This lets you enter and edit transmit and receive frequencies from 42.0 through 54.0 MHz.
Changing the Displayed Range for 6-meters:
One more cosmetic change really needs to be made. The list of acceptable frequency ranges (on the F4, F9 menu mentioned above) should be changed to reflect the new band upper limit. This is a simple ASCII null-terminated text string and Hex Workshop can find the exact location for you (there's only one occurrence of the string "50.0"). This string starts at hex address 39337:
The above 17 bytes cause the string "42.0 - 50.0 MHz" to be displayed.
Change the byte at location 3933F from 30 to 34 to change the displayed text to become "42.0 - 54.0 MHz".
Save the file and you should be good to go. No more hex editing of the radio's code plug or worrying about reviewing the frequency values in RSS. Start RSS, read the code plug, make your changes, save the code plug to disk, and write the code plug to the radio. This is how it works on 42-50 MHz. This is how it should have worked on 42-54 MHz too.
Changing the Lower Band Limit for 10-meters:
The software frequency limitations are stored in two separate areas within the P200LB.EXE file. One specifies the lower limits; the other specifies the upper limits. We're now only concerned with the lower limit, which restricts frequency data to 30.0 MHz. The values are stored as 8-byte, double precision, floating point values. Hex Workshop (and probably any hex editor) can find the exact location (there's only one occurrence of the double precision value 30.0). This value is stored starting at hex address 3A0B2:
3A0B2: 00 00 00 00 00 00 3E 40
The above eight bytes represent a value of 30.0 decimal.
Change the byte at location 3A0B8 from 3E to 3C to change the lower limit to 28.0 decimal. This lets you enter and edit transmit and receive frequencies from 28.0 through 36.0 MHz.
Unfortunately, there's another limitation lurking around that I didn't find because I didn't have a radio to try to program. A reader made these changes and found he still couldn't go below 29.5 MHz. He searched for that value, found it, and changed it to 28.0 and that allowed him to enter frequencies down to 28.0 MHz. This value is stored starting at hex address 3A6DB:
3A6DB: 00 00 00 00 00 80 3D 40
The above eight bytes represent a value of 29.5 decimal.
Change the byte at location 3A6E0 from 80 to 00 and change the byte at location 3A6E1 from 3D to 3C to change the lower limit to 28.0 decimal. This creates the same value entered at location 3A0B2 and it lets you enter and edit transmit and receive frequencies down to 28.0 MHz.
Changing the Displayed Range for 10-meters:
One more cosmetic change really needs to be made. The list of acceptable frequency ranges (on the F4, F9 menu mentioned above) should be changed to reflect the new band lower limit. This is a simple ASCII null-terminated text string and Hex Workshop can find the exact location for you (there's only one occurrence of the string "30.0"). This string starts at hex address 39315:
The above 17 bytes cause the string "30.0 - 36.0 MHz" to be displayed.
Change the byte at location 39315 from 33 to 32 and change the byte at location 39316 from 30 to 38 to change the displayed text to become "28.0 - 36.0 MHz".
Save the file and you should be good to go.
Acknowledgements and Credits:
Motorola, MT1000, P200, and RSS are trademarks of Motorola, Inc.
Hex Workshop is a trademark of BreakPoint Software, Inc.
Dave N1OFJ tried this modification on his low-band MT1000 and reports it worked just fine.
Mike WB8VLC/7 submitted the info for the MT1000 program.
Mark W1ACP asked about the 10-meter modificationss and also found the 29.5 MHz limitation. He reported back that his 33 MHz MT1000 programmed right up and works fine from 29.100-29.600 MHz with 6 watts across that range.
The author can be contacted at: his-callsign [ at ] comcast [ dot ] net.
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This page originally posted 08-May-10.
Article text, layout, hand-coded HTML Copyright © 2010 by Robert W. Meister WA1MIK.
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.