[hpsdr] Proposal for a 'low-end' RX/TX board for HPSDR

[Philip Covington]

On 7/27/06, Ahti Aintila <oh2rz.sdr at gmail.com> wrote:

> Phil,
>
> You are talking so nicely about the active integrator, so I have no
> alternative  but admit. Being a simple and silly person myself, I love
> KISS. Here is my latest simple schematic
> diagram:<http://kotisivu.dnainternet.net/ahti/sdr-1000/newmix4.pdf>
>
> I figured out that the OPA1632 is a combination of two inverting
> amplifiers, so why not they could not work as two integrators.
> Unfortunately, I am still waiting for the ordered components to come,
> so no tests made yet. This is just a paper exercise. If this idea
> works the QSD (and QSE likewisw) can be put to a really small area.
>
> By the way, I like isolating tranformers to separate the dirty digital
> world from the sensitive analog circuits.
>
> What do you say, and what am I missing this time?
>
> 73, Ahti OH2RZ

Ahti,

Here is another circuit to look at:

<http://www.philcovington.com/HPSDR/TEMP_STUFF/isd_07282006-1.pdf>

Using a quad op amp reduces the component count even further and there
is still differential output.

73 de Phil N8VB

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