Upgrading AllStar Node’s Radio to Maxtrac
Why Upgrading?
When someone gives you Motorola Maxtrac UHF version for free you take it without asking questions!
The Maxtrac is reliable and robust radio and for quite a while I wanted to upgrade because of low power of the chinese QYT which transmits 5w in high power mode (and 4.5w on low. what a joke).
COR Line Mod
The Maxtrac I got is 5 pin version which is limited and doesn’t have COR signal like the 16 pin board has so I had to modify it with small wire and resistor to pin 1 on the microphone jack.
More info can be found here: http://www.repeater-builder.com/motorola/maxtrac/maxtrac-interfacing.html#5-pin
Programming
After connecting everything with RJ-45 to female pin header (like I did with the QYT, with the same order of wires) it was time to test it.
When testing, I noticed that the Maxtrac is transmitting weird noise in the end of every transmission like I used to hear on taxis.
Did some research and found that it’s called PTT-ID or ANI and that my version of Maxtrac shouldn’t have that.
After consulting with some experts, I did a reset to the board and it’s gone.
The programming done with old PC and the Motorola RIB. Very messy.
Tweaks
When the hardware was done, I had to check the Allstar configuration.
Using simpleusb-tune-menu script, I changed the RX and TX audio levels to fit this radio.
Power
The power output of the Maxtrac is around 40 watts.
Using 40w isn’t ideal for Allstar node and will require some serious cooling.
So turning it down to 10w should be OK.
When I asked someone, he told me not to use the RSS software to decrease the power.
The reason, according to what he said, is that the CPU has a table of frequencies and power values.
The ham band is out of the range of the Maxtrac (449-470 MHz) so when the CPU tries to check what value to use against the table, it founds nothing and can use some weird values and output more than 100% of it’s power capability.
Thus, there’s modification for it here:
http://www.repeater-builder.com/motorola/maxtrac/maxtrac-manual-rf-power-control.html
This mod uses potentiometer to adjust the resistance and bypass the CPU control over the power output.
I didn’t do this mod yet and decreased the power with the RSS software for now (tested with meter) it’s seems to be stable but having manual control would be more safe way to go.
Maybe in the future.
That’s it for now.
If you have any comments or question, type it in the comments section.
73!
