Hello Clemens,
At the moment I am playing with the RX LF Ensemble.
It is an amazing kit.
Lying unscreened on my desk between my keyboard and monitor it is an
awesome performer at LF and lower HF.
I use WRplus and the audio is very good.
This afternoon I heard a VR2 station from Hongkong on 40 meter.
It was quite weak and the channel was overlapped from both sides by much
stronger contest stations.
The amazing thing was that the strong overlapping signals did not take
over the channel.
The VR2 was still clearly audible underneath the interfering stations.
This direct conversion concept has it shortcomings; e.g. the 3 x LO mixing
problem.
I found that the mixing products of 3 x LO are only 10 dB weaker than the
wanted products.
Hence for LF a good 500 kHz low pass filter is mandatory to get rid of
false broadcast stations from MW.
And one needs a decent (external) soundcard.
I use a EMU 202, which has peculiarities of its own.
I have not seen exact phase noise figures for the Si570 LO chip.
However at LF the output of the Si570 is devided by 16, which certainly
will improve the phase noise figure.
Subjective as a receiver it is as good as my PERSEUS.
Direct sampling is the way to go, but as a low cost introduction to SDR,
these DC receivers should not be overlooked.
73,
Roelof, pa0rdt
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