[TenTec] Pegasus / Softrock 5

[Mark Erbaugh]

Duane,

Thanks for the reply.  I went back and reviewed your original posting.

> http://lists.contesting.com/archives//html/TenTec/2004-12/msg00116.html

> In the case of the Pegasus and its design similar siblings I
> often thought that the 45 MHz IF is the best place to apply
> this idea. Unfortunately in the case of the QSD that high of
> a frequency is a bit of a challenge to get to. Although I
> think decent results could also be had by applying the QSD to
> the 455 kHz IF of the Pegasus instead. The other limitation
> of using a radio like the Pegasus or its sibs for such work
> is that the 45 MHz IF roofing filter will limit any
> QSD/external DSP IF to ~15 kHz of bandwidth. To me that is
> too restrictive given the increasingly common use of 96 kHz
> bandwidth in the SDR radio programs like Rocky, PowerSDR, and
> Winrad. I suppose if you only want a narrow bandwidth IF then
> that is not an issue (that's exactly what I had with the CII
> experiments I did). I suppose with some creative design you
> could actually do both bandwidths, narrow for optimal DR
> performance and wide for panadapter purposes.

I hadn't really looked at the Pegasus mixing scheme, which kind of messes up 
what I was thinking about. I was really thinking about using some frequency 
in the Pegasus (I forgot about the 45 MHz) as the VFO for the QSD.  That 
would require a frequency near the intended tuning range, which probably 
doesn't exist in the Pegasus.


> Also in the case of the Pegasus and its sibs the prospect of
> TX with a QSE (or any other baseband to RF mixer scheme) may
> be a bit challenging to implement, not likely to be a
> "restorable" mod to make. For some reason I can't ever bring
> myself to making mods of this level to a radio that can't be
> undone.

I figured I'd just use the Pegasus' transmitter.


> And finally I do know that there are some that are taking the
> 12 kHz IF out of the RX 320(D) and feeding it directly into
> Winrad. This works because Winrad does not need I/Q inputs to
> work. This was discussed within this last week on the RX 320
> group on Yahoo.

I have modified both my Pegasus and my RX320 to bring out the 12 kHz IF and 
have decoded that with a computer, but I was thinking that a QSD mixer might 
work better, plus you would be able to get twice the bandwidth if you have 
both I and Q - though I hadn't thought about the roofing filter.

73,
Mark