[hpsdr] Alex update?

[Henry Vredegoor]

Hi John, All,

Thank you for your explanations!
Will these informations and measurements be made available somewhere? 
(Alex Wiki)

Thanks again for all your good work.

73's


Henry.


John Ackermann N8UR schreef:
> Henry, for the most part the toroids had somewhat different inductance 
> than specified but other than that performed OK.  So the main work has 
> been changing the turns count to get the correct inductance, and in a 
> couple of cases changing the associated capacitance to optimize the 
> filter performance.
>
> After adjusting for the changed changed inductance, the stopband loss, 
> insertion loss, and power handling weren't much different between the 
> spec'd and actual toroids.
>
> (We did network analyzer measurements of each filter with both the 
> spec'd Amidon toroids and the Chinese ones -- over 40 captured data 
> sets in all -- as well as 100W saturation tests of the transmit 
> filters to measure both heating and spurious generation.  These 
> filters are *well* characterized!)
>
> John
> ----
>
> Henry Vredegoor wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Hi Scotty, Graham, All,
>>
>> I have a few technical questions about the changes for Alex; could 
>> you please explain a little bit more?
>>
>> - I understand that the currently used cores are manufactured in 
>> China, a lower price beïng the main reason for doing so, but that 
>> they initially did not meet the quality standards of TAPR; where/why 
>> more exactly didn't they meet the spec?
>> - The circuits of the filters had to be changed to accommodate the 
>> China manufactured cores.
>>   Are the quality or spec's  of the filters on the Alex boards 
>> compromised by this change and if yes what are the resulting 
>> differences/new specs/consquences?
>> - Would it still be possible to use the original cores (for maybe 
>> better quality or  tighter specs) ?
>>
>> I hope I am not bugging you too much with my questions, I highly 
>> appreciate the outstanding job you are doing for us all.
>> But "Ham-Radio minds" want to know.......................    :-)
>>
>> 73's,
>>
>> Henry.


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