The TS-450S radio and related series(TS-850, TS-690) has a connector in rear panel labelled as DSP2. This connector was original used to supply the 4th IF to optional DSP-100. This signal has a frequency of 36.891 KHz, so with a simple converter it can be moved to 12KHz, then sampled with a computer's soundcard and processed with any SDR software.I use this signal to receive the Digital Radio Mondiale with Dream Software.
I made a prototype converter, based on a double balanced mixer. Now I am working in a more sophisticated mixer with less intermodulation and higher SNR.
The prototype
