[hpsdr] Alex update from Toroid Hell

[Dan Mitchell]

Scott;
Thanks for the quick and complete update.
Dan, W0IQ

-----Original Message-----
From: hpsdr-bounces at lists.openhpsdr.org
[mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of Scott Cowling
Sent: Wednesday, August 25, 2010 9:50 AM
To: hpsdr at openhpsdr.org
Subject: [hpsdr] Alex update from Toroid Hell

***** High Performance Software Defined Radio Discussion List *****

Hi Dan & patient Alex co-sufferers,

Here is the current state of Alex...

We received all of the toroids. There are 22 different core/turns
combinations.

Of the 22 types:
4 are wound on the incorrect cores (70% - 85% to high in permeability)
8 others measure out of inductance tolerance by more than 10%
10 are useable with no circuit changes

Graham is evaluating the filters containing the 8 out-of-tolerance 
inductors to see if he can tweak the values of the other components 
to compensate for the larger inductance. If not, we have an alternate 
plan to modify these 8 toroids locally to remove one or more turns, 
strip and re-tin the wires to get the inductance to where it needs to be.

On the 4 that are wound on the incorrect cores, the manufacturer has 
agreed to re-wind these on the correct cores. However, even this 
inductance is proving to be 15% to 30% too high, so Graham is 
evaluating that impact so that we can adjust the number of turns to 
get the target inductance.

Graham's work should be complete next week. We can then get the CM 
started on the rewinding and we can modify any of the 8 others that we need
to.

I do not have a timetable for the rewinding, but I'll post an update 
once we get a commitment from the CM.

Sorry it has take so long, but we are maintaining our quality 
standards (such as they are) by being very careful with these. I 
would hate to have 400 assembled units in my warehouse that had 
defective filters due to incorrect inductance values. Almost as much 
as you would hate to have one hooked up to your antenna. :-)

I should have another update (maybe even new toroids!) by DCC.

You are going to DCC, right???? This year's line-up is looking pretty 
impressive, and Vancouver, WA (across the river from Portland, OR) is 
very nice. Steve assures me that the schedule will be up shortly at:

http://www.tapr.org/dcc.html#intro

The Sunday seminar alone is worth going for: Rick Muething KN6KB will 
be talking about DSP Tools, Techniques and Tips. This is a 4-hour 
seminar on how to get started in DSP. If you are interested in DSP 
but don't quite know how to get started, this one's for you.


73,
Scotty WA2DFI

At 06:25 2010-08-25 -0700, Dan Mitchell wrote:
>***** High Performance Software Defined Radio Discussion List *****
>
>Is there any recent news on how TAPR is doing with the Alex?
>Dan, W0IQ


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