I know that there is a hardware replacement kit that is available for Osmocombb phones that help make the phones be used as uplink sniffers, but unfortunately the kit uses components that operate in the European GSM bands. Are there any hardware replacement kits for Osmocombb phones that operate in the U.S. GSM frequency bands?
The HHM1526 balun is specified for both PCS and DCS and the one for the lower band should be close enough.
Cheers,
Sylvain