[hpsdr] ATLAS PCB fab status ??

Tue Mar 28 15:38:26 PST 2006

Note to Phil

On the next Atlas model put in 2 pads that go 'nowhere just for show'(as
Tevye sung) for the obligatory Red wire jumper (my wire wrap stuff is red)
It Fools people looking at it into thinking that we are not perfect. (Knock
Wood)

(*smile*)
Eric

-----Original Message-----
From: hpsdr-bounces at hpsdr.org [mailto:hpsdr-bounces at hpsdr.org] On Behalf Of
Eric Ellison
Sent: Tuesday, March 28, 2006 6:29 PM
To: 'Ray Anderson'; 'High Performance Software Defined Radio Discussion
List'
Subject: Re: [hpsdr] ATLAS PCB fab status ??

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

Ray

You'll have one of the boards. I agree that electrical integrity rather than
the more sophisticated tests is in order for meshing with the desire of
folks who have ordered the now "Production Model" is the most important.
However, if you notice in your testing that we might include active/passive
termination, we could either go with a second alpha or discuss to see if it
makes this fundamental product in the chain better than it is. A week or 2
turn around for boards is great, and worth the test to avoid the "Blue or
Yellow (if you are KD5TFD) obligatory jumpers. I'd rather have the 'added'
jumper just for show, rather than really needed to make it work!

Thanks
Eric

-----Original Message-----
From: Ray Anderson [mailto:ray.anderson at xilinx.com] 
Sent: Tuesday, March 28, 2006 6:06 PM
To: Eric Ellison; High Performance Software Defined Radio Discussion List
Cc: Ray Anderson
Subject: RE: [hpsdr] ATLAS PCB fab status ??

Eric et al :

I'd expect that if one were to run a VNA test on the signal lines you'd
find the impedance to be around 55-60 ohms for the internal traces and
around 75-80 ohms for the external ones with lots of high-frequency
resonances (in the GHz region) due to the unterminated connectors acting
as open stubs. Same thing if you TDR the lines. With all the open
unterminated connectors you'll have a morass of reflections. To do tests
that mean anything with either a VNA or a TDR you need to have a pretty
decent probing technique. You probably could get by with a chunk of thin
micro-coax soldered to a two pin header to push on the .100 spaced pins
of the DIN connectors you could probe between ground and the y-bus on
one side of the connector (columns a & b) and the x-bus on the other
side (columns b & c). One could plug and unplug the probe across the
width of the connector checking the impedance profile for gross
differences in a fairly short amount of time.

My gut feeling is that a few hours of time spent with a ohmmeter would
probably be just as informative at this point. You could look for opens,
and shorts to adjacent lines and power busses. Some of these would be
tough to find with a VNA or TDR due to probing limitations.

I've got a set of connectors on hand and both a VNA (Agilent 300 kHz to
20 GHz) and a pair of Tek TDR's in my lab downstairs. Once I build up a
unit I could scan all the lines with a VNA in pretty quick order at
lunchtime.

If you want to send one of the boards to me when they come in I'll take
on the VNA testing (and maybe some TDR checks) as well as ohmmeter
checks for power opens, shorts etc.

-Ray	WB6TPU

Raymond Anderson
Senior Signal Integrity Staff Engineer
Product Technology Department
Advanced Package R&D
Xilinx Inc.

-----Original Message-----
From: Eric Ellison [mailto:ecellison at comcast.net] 
Sent: Tuesday, March 28, 2006 5:21 PM
To: 'Robert W McGwier'
Subject: RE: [hpsdr] ATLAS PCB fab status ??

Bob.

Beats me! (smile)

Well, I guess the obvious is to build up the external connector(s)
section
with all parts. Power on tests, with an ATX supply make sure power is
where
it should be at all connectors and not where it should not be on any of
the
buss lines. Test on-off cold switch function leds etc. Test of ease of
soldering with the thermals. 

It would be nice to see if we could run some dynamic tests on the
traces.
See how fast we can go, perhaps try lvds on various buss members.
Reflections? Impedance?

Final test with a Tinus Olsen (I have one at work we use for 2x4s) for
bearing load.

Ray, can you help me out here? Anyone else? I hate to show my ignorance
but
it's shown! Dan, elaborate on the VNA and possible tests? Phil VK6APH
and
Rick - VE3MM have them working.

Thanks
Eric

-----Original Message-----
From: Robert W McGwier [mailto:n4hy at idaccr.org] 
Sent: Tuesday, March 28, 2006 12:31 PM
To: p.convington at gmail.com
Cc: Eric Ellison
Subject: Re: [hpsdr] ATLAS PCB fab status ??

Please tell me the tests you want run.

Bob

Lyle Johnson wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>   
>> Bob - N4HY , Lyle - KK7P, As Amsat engineers / developers can you or 
>> someone in Amsat bench test one or more of these protos?
>>     
>
> I'm afraid I could only do the simplest of tests at the moment.
>
> Lyle KK7P
>
> _______________________________________________
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>
>   

-- 
Robert W. McGwier, Ph.D.
Center for Communications Research
805 Bunn Drive
Princeton, NJ 08540
(609)-924-4600

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