[TenTec] AM Receiver distortion in Orion II

[Barry N1EU]

On 1/24/07, Paul Christensen <w9ac at arrl.net> wrote:
> The O2 has a sharp AM audio response cutoff at exactly 3 kHz (6 kHz of BW),
> as expected.  On the FFT display, it is clearly a very sharp DSP cut-off
> with no detectable skirt.  Audio response cuts off at 3 kHz and nothing
> escapes beyond that point.  The O2 low-end response extends to below 80 Hz,
> but rolls off smoothly below 90 Hz.

I just ran my v1.373 O1 audio through SpectraPlus.  In AM mode, with
6Khz selectivity there is a full 6Khz of audio bandwidth (NOT 3Khz as
Paul noted in the O2).  On the main receiver, the effect of the 6Khz
roofing filter can be seen as a gentle (10dB/octave) roll off above
3Khz.  Manually switching in the 20Khz roofing filter restores the
full 6Khz audio bandwidth to the O1 main receiver and makes it
virtually identical to the subreceiver.

73,
Barry N1EU