[hpsdr] Alex update?

[Henry Vredegoor]

Hi John, All,

Thank you John for the example diagram.
Of course I didn't mean to have "all" the data in comparison be 
availlable, just enough to get some idea/illustration of the problems 
you were having during the developement of "Alex-With-The-Chinese-Cores" 
(  ;-)  )
The example diagram of  the 80M LPF section gives a good idea.

After refreshing my knowledge a little by re-reading the Wiki pages for 
Alex etc., I was wondering if an IP3 check/measurement was/will be done 
with the combined boards of Mercury and "Alex-With-The-Chinese-Cores" (I 
read on the Wiki that this was done by Phil - VK3APH with good results 
for the original Alex)
I could imagine cores fabricated by different manufacturers having 
impact on this figure?
Or is this somehow obvious (for the people with the appropriate 
knowledge anyway.... ;-)  ) from your measurements-data?

73's,

Henry.

John Ackermann N8UR schreef:
> The measurements on the original alpha board with Amidon toroids are 
> on my website at http://www.febo.com/pages/alex/index.html .
>
> I'm not sure how useful the comparative data are, since Graham has 
> made a number of circuit changes based on those results and therefore 
> they don't really bear resemblance to the production version.
>
> Just to give an example, though, attached is a plot comparing the 
> original ("old") and Chinese ("new") toroids in the 80M LPF section.  
> In this case the old and new cores track quite closely, but some of 
> the other filters showed more substantial discrepancy, and as a result 
> of these tests Graham has made significant further adjustments to some 
> of the filters.  (The data is from an Agilent 8712ES network analyzer.)
>
> We'll plan to do the same tests on the production units, but the fly 
> in the ointment is that we may get those in hand just as I'm packing 
> up my basement for a move to another city, so I can't guarantee the 
> timing.
>
> John
> ----



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