FMCOMMS5 - Transmission using external amplifier ADL5602

Hello,

We use the board FMCOMMS5 and we tried to use the external amplifier ADL5602 on the Tx channel of the AD9361

https://ez.analog.com/wide-band-rf-transceivers/design-support/f/q-a/80396/fmcomms5-works-in-wide-tuning-range

We noticed that the pass band filter (Johanson Technology @ 2.4 GHz) before the amplifier ADL5602 kill the polarisation voltage at the input of the amplifier.

The output power of the amplifier is then very low and not expected!

Could you confirm that the current design must request to insert a capacitor between the pass band filter and the amplifier to polarize the amplifier or a filter which not shorcut the DC?

Regards,

Patrick