Up one level (MaxTrac index) Up two levels (Moto index) Back to Home

Converting a Trunking 900 MHz MaxTrac to Conventional An Alternate Method By Greg Stahlman KJ6KO HTML'd for Repeater-Builder by Mike Morris WA6ILQ

A note from Mike WA6ILQ:
A recent thread on the AR902 Yahoogroup (which is oriented exclusively towards the 902 MHz Amateur Radio frequencies) covered converting a 900 MHz Maxtrac from trunked to conventional operation. The method discussed there works, but Greg described an alternate method that is simpler. I sent him an off-list email asking him write something up. I suggest that you read Bob Meister's article first for the background information there. Here is Greg's writeup:

This procedure simplifies the conversion process so only ONE program is required to do the conversion and NO realignment is necessary.

You will need:

• Maxtrac Lab Conventional RSS
• The 900 MHz Conventional Firmware FVN4019A burned into a 27C256 EPROM
• An operational 900 MHz trunking maxtrac that has NOT been previously blanked and is in "decent" alignment

First open the radio and replace the existing trunking firmware EPROM with the replacement FVN4019A firmware. Be careful that you don't fold a pin underneath, and make very sure that the notch in one end of the chip goes towards the RF shield. See the photo below. BE CAREFUL not to install the EPROM backwards!! It is instant death for the EPROM chip if you do!

Yes, the photo shows VHF / UHF firmware, but it also shows the notch...

If you try to blank the board with the trunking firmware still in it while using conventional RSS, it will give you the dreaded "MODEL NOT SUPPORTED".

Now power up the radio. It will probably not operate and nothing will be on the display...this is OK.

Now connect to the computer, open the CONVENTIONAL LAB RSS.

Follow this procedure:

• F2---SERVICE
• F8---MAKE BLANK BOARD
• F3---MAKE BLANK BOARD WITH NORMAL CODEPLUG / SAVE OLD TUNE DATA

Ignore the warning about "losing all data" and F2 to continue. It will take about 10-15 Seconds and it will return you to the service screen when it is done.

Now...

• F6---BOARD REPLACEMENT
• F2---LOGIC BOARD

Click on the picture for a larger image

The F3 screen - ignore the color shifts, they are a product of the digital camera

Important: If the F3 option that is hhighlighted in yellow above is missing that means that the board was blanked using F8 "DO NOT SAVE OLD TUNE DATA"!
If you accidently blanked the board using F8 instead of F3, the F3 option will be missing and you will have to do a complete alignment on the radio!

It will now ask you for information. Enter the following:

• PRODUCT LINE... "MAXTRAC HIGH SIG"
• MODEL NAME... use "MAXTRAC 300"( if it is a 16 channel radio) or "MAXTRAC 100" (for a 2 channel radio)   (see note below)
• RANGE... "896-941"
• MODEL #... Should already be filled in. Verify number of channels and the RF power of the radio. There are only a couple choices here. 2ch or 16ch... and 12 watts or 30 watts.
• PANEL #... "000" for 2 channels or "001" for 16 channels (see note below)
• SERIAL NUMBER... read the radio tag and fill it in
• NOW...F3...PROGRAM RADIO WITH OLD TUNE DATA....     NOT F8 !!!!!

Note: You can convert a 2 channel Maxtrac to a 16 channel radio by replacing the 2 channel faceplate with one from ANY multi channel Maxtrac (even a super-cheap 800 MHz trunking one). BUT... you MUST swap the microphone connector and "HEARCLEAR" board from the old 900 radio faceplate into the replacement faceplate as the microphone jack and associated circuit board from the 900 radio is SPECIFIC TO THE 900 RADIO!!

Now read the radio and program the channels. NOTE the SCAN button and the rest of the buttons will now be in different locations than they were in a trunked radio. Your "new" panel will function as below:

You can buy a replacement excutecheon from Moto if you like. The multiple-channel conventional escutcheon is part number 1380277L01, for the 2-channel conventional escutcheon change the last character of the part number from a 1 to a 2.

Read the MAXTRAC USER'S MANUAL for instructions on the SCAN functions and other operational features.

At this point the radio has now been initialized as a conventional radio. Turn it off, disconnect the power cable, replace the shield over the microprocessor on the logic board, put the plastic cover(s) back on, and remount the control head to the front of the radio.

I have made several tests and verified that the old tune data is NEVER removed from the radio by "Saving Old Tune Data". It was originally thought that the data was temporarily stored on the computer, but it is not. I tried several things to "brick" a Maxtrac this way like shutting off the radio and resetting the computer between blanking and programming the radio and the radio NEVER lost the tune data. You can actually blank a radio, put it on the shelf for a week and come back and initialize it and the old tune data will still be in it! The worse thing that happened was shutting off the radio or computer in the middle of programming the radio or in the middle of a "FULL ALIGNMENT". When it was restarted, the radio gave a constant "death howl", but I was able to start over with the process and when I got to where I was when it was shut off, the "death howl" stopped and the radio worked fine... still with the old tune data!

If the radio doesn't work satisfactorily, you may, on rare occasion, have to return and do a complete alignment, which requires a GOOD service monitor, a test setup for the Maxtrac and about 45 minutes to an hour.
Some people would rather do a complete alignment anyway, and that's OK, but I have done about one hundred 900 MHz Maxtracs this way for myself and others (we have a large 900 MHz group here in the Sacramento, California area), and have never found one that needed it. Most of us don't have the required equipment to do a proper alignment anyway!

Some other notes on 900 MHz MAXTRACS...
The logic board (actually the audio/logic board) is the same on the low band, high band, uhf radios, and is unique on the 900 MHz radios. The 900 MHz board is unique and has several differences, two of which are important to us:

• First, unlike the low band, high band, uhf radios the JU 551 jumper on the logic board HAS NO AFFECT on the de-emphasis of the audio that feeds pin 11 on the accessory jack.
  This is because in the 900 MHz radio the de-emphasis is done in the "HEARCLEAR" circuitry on the microphone connector / HEARCLEAR board! JU 551 will only select between raw discriminator audio and squelched, high-pass-filtered (PL Filtered) receive audio. The pin 11 audio will NOT be de-emphasized either way! If you want de-emphasized receiver audio, you need to pull it from pin 8 on the microphone jack. If you want de-emphasized receiver audio on the 16 pin accessory connector you need to jumper the center pin of JU 551 to pin 8 on the microphone connector.
  
  
• Second, the microphone input (pin 2) on the 16 pin accessory connector is NOT pre-emphasized! Again, this is done in the HEARCLEAR circuitry on the microphone connector / HEARCLEAR board. If you want pre-emphasized transmit audio, you must use the microphone jack on the front of the radio, perhaps with a DC-blocking capacitor in line. The rear connector does work, but it delivers non-pre-emphasized (flat) transmit audio.

MaxTrac, PL, DPL, HearClear, and a whole lot of other things are trademarks of Motorola, Inc.

Contact Information:

Greg can be contacted at: his-callsign [ at ] innercite [ dot ] com.

Back to the top of the page
Up one level (MaxTrac index)
Up two levels (Moto index)
Back to Home

Article posted 05-Jun-2010

Article text copyright 2010 by Greg Stahlman KJ6KO
Conversion to HTML © Copyright 2010 for Repeater-Builder by Mike Morris WA6ILQ

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.