OsmocomBB

h2. Motorola filter replacement

In order to use the phone as a passive uplink sniffer, you will have to remove and replace the RX filters.

To replace filters on Motorola phones you will need:

* "HHM1526":http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=HHM1526

* "HHM1523C1":http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=HHM1523C1

* "04025A150JAT2A":http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=04025A150JAT2A

* "04025A220JAT2A":http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=04025A220JAT2A

h3. Remove existing baluns

First you will need to remove existing balun:

{{thumbnail(motorola_filter_replacement_step_1_low.jpg, size=250)}}

{{thumbnail(motorola_filter_replacement_step_2_low.jpg, size=250)}}

h3. Solder new baluns

Clean up the phone and solder HHM1526 and HHM1523C1 on the right places (the black dot goes up):

{{thumbnail(motorola_filter_replacement_step_3_low.jpg, size=250)}}

{{thumbnail(motorola_filter_replacement_step_4_low.jpg, size=250)}}

{{thumbnail(motorola_filter_replacement_step_5_low.jpg, size=250)}}

h3. Solder ceramic capacitors

Last step is to solder ceramic capacitors 04025A150JAT2A and 04025A220JAT2A:

{{thumbnail(motorola_filter_replacement_step_6_low.jpg, size=250)}}

{{thumbnail(motorola_filter_replacement_step_7_low.jpg, size=250)}}

h3. Credits

Thanks to "Sylvain":http://246tnt.com/gsm/rx_filter.html and Peter who made this possible.