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

[Ray Anderson]

>> 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

While compiling an order of prototype parts to experiment with various
QSD designs I found that the 75auc1g66 that Bob used appears to only be
available via normal distribution channels (i.e. Newark an Digikey) in
the CSBGA (chip scale BGA) package while the 74auc2g66 is plentiful from
both sources in a leaded SSOP-8 package.

It looks like the 74auc2g66 is easier to work with and also has the
advantage of having two independent switches inside a single package
which would cut down on the layout size.

The 74auc2g53 that Phil is proposing  appears to be readily available in
the SSOP-8 package.

-73's de Ray  WB6TPU



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