[hpsdr] Some answers to call for comments for the design of ALEX

[Henry Vredegoor]

Comments solicited:
1. Too many external (BNC) connections? Or not enough?

----> I think the amount of BNC's is OK. Individual choices can be made by
populating less or all BNC's

2. Would you be willing to assemble this yourself, as opposed to purchasing
a manufactured module? 
    It is a mix of through-hole and some surface mount components, and will
also require some mechanical assembly. 
    It is not the kind of assembly that most contract manufacturers are used
to dealing with. 
    I could limit the surface mount components to larger pitch ICs and
larger passives.

---> I think it will be most cost effective if the boards can be assembled
by DIY. (Saves us in the EU probably also up to 20 % VAT as well.......)
      Larger pitch IC's / more thru hole components is better for people
with less DIY experience.

3. There are about 20 ea. T-50 toroids and 5 wire coils that will need to be
wound. 
    Would you prefer a kit of pre-wound toroids?
    Or would you rather wind them yourself?

---> Same as for 2:  A kit of pre-wound toroids could be easier for less DIY
experienced people and could have the advantage that the coils could have a
tested inductance.
      Also another separate kit for all the other components please if
possible !


Additional/questions remarks:

- Did I miss something and was the digitally continuously tuned
preselector/filter idea abandoned and are we back to a number of fixed
filters?

- Where is the receiver protection? I think it should be closest to the
antenna and as far away as possible from the sensitive electronics.

- Why not use relays for ALL the switches instead of using Hittite switches
for the receiver? Simpler BOM, consistency?

- What about daisy chaining of filter-boards (e.g. say I want a 16 X RX
bandpass filter configuration)

- Since it seems we are back to individual filters and seeing the
resemblance between the RX and TX block diagrams, would there be a
simplification possible by designing just a single board for use in both an
RX- and a TX configuration?
 Filters could be separate modules (as suggested already in the previous
discussions) layed out for individual preferences. (Frequency, Filter
architecture type, low- high- or band-pass, LNA)
It would contain only the power supply, the  relays, the switching logic and
mounting space and connection points for the individual filtermodules.

This would require however another separate, (remote- ?) "RX/TX switch over,
SWR-bridge, antenna-select, receiver protection" board/unit of some sort.
(Quite a different setup, I am aware of that, but it would be my personal
preferred solution)

73 's,

Henry.

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