I am using for DAB-DX the Sangean DPR-69 Plus portable radio. To connect an external antenna I drilled a hole on the left side of the radio and mounted a bnc female connector.
Inside the radio the little coax from the receiver board to the telescoop whip antenna is desoldered from the whip antenna. Then the coax is reconnected to the bnc connector.
The antenna is an 10 element Yagi DL6WU Design. The pre-amp is mounted near the dipole feedpoint of the yagi antenna. The pre-amp is dc powered via the coax cable. I inserted into the coax cable a dc inserter.
Watch out that never the dc is put directly on the bnc connector of the radio. The receiver input is dc shorted and probably the input coil would be destroyed. Maybe its better to put a condensator in serie. Someday I will do that.
The pre-amp is homemade. I use a 3SK183 dual gate GaAs Fet, the Gain is 18.8db and noise figure 0.24db. Below a picture of the measured values. This pre-amp is very important part in the DAB receiving system.
The antenna and pre-amp are only covering DAB channel 10D - 13A. For the lower part of the DAB band a seperate antenna and pre-amp is used.