[hpsdr] HPSDR signal overload

[John Petrich]

All,

I want to speak to Steve's, K9SRB,post.  What Steve is describing is that
the receive DAC in Mercury acts like a broadband power meter.  That is, the
total signal power in the receive spectrum at the receiver input registers
in the DAC.  So, all RF source, at any frequency, in the HF spectrum will
effectively accumulate at the input to the DAC.  My QTH in  Western NA  is
mercifully remote from super strong HF broadcasting stations that afflict
our European colleagues.  My solution to front end overload is to put an HP
filter at the input to Mercury, with a cut off frequency of about 1500 KHz.
The powerful local BC stations are thereby attenuated, and the dynamic range
of the DAC is largely preserved.  My view is that for most American hams,
the input HP filter provides sufficient filtering to markedly reduce the
potential of Mercury front end overload.

Regards,
John, W7FU