I have a test setup comprised of an ADF7021 tied directly to a circuit shown below
The problem is that the power output is too low and the RF MOSFET gets hot pretty fast.
The frequency response of the lowpass part is far from being optimal. 2nd harmonic is at -10dBc. I have already proposed a change here: https://github.com/M17-Project/TR-9/issues/3#issuecomment-727211097
http://www.elenota.pl/datasheet-pdf/161389/Renesas/RQA0009?sid=855aac943830b7e4cdd6c1448ed59464 (page 10)
The quality from DMR radio to M17 is magnificent. This is with the PCM information passed straightforwardly from the md380 vocoder to the codec2 vocoder. I added a setup alternative ‘GainAdjustDb’ in DMR2M17.ini with a default setting of - 6dB for PCM information got back from codec2, on the grounds that without this degree of weakening the M17 transmissions were smothering my DMR radio speaker. Estimations of - 6dB to - 10dB appear to get the sound to a healthy level. google
Wrong topic, but thanks for the feedback