[Gb-ccb] Ka Band Receiver / CCB Test Update...

[Brian Mason]

Thanks Randy, Jason.

My last hot/cold in the lab, with ccb+receiver, was 19oct. At that point I 
believe that we did *not* have the new cables between the ccb+receiver-- 
the new cables were completed and installed only after the Ka receiver had 
gone back up for spectral line commissioning. The 19oct levels showed the 
expected (4500 count vs cold, 12000 count vs hot) power levels, and are 
summarized in a file called ccbTsys19oct05.pdf that I think I sent to the 
mailing list the following week.

  Brian

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Brian Mason                           | office: +1(304)456-2338
Associate Scientist                   | fax:    +1(304)456-2229
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On Sat, 19 Nov 2005, Randy McCullough wrote:

> All,
> 
> Jason and I spent some time today sorting out the proximate cause for the
> anomalous readings seen last week with the Ka Band Receiver/CCB setup.
> 
> As you'll recall, Brian reported that, when looking at the sky, he would expect
> to see total power counts of about 2,000 to 2,500; but, instead, all channels
> seem to be setting somewhere around 14,000 to 14,500 counts.
> 
> After going through many gyrations, Jason and I determined that the new
> TWINAX cable sets had actually swapped the polarity of our differential
> signals going into the CCB's input ports...
> 
> Since this would make our readings appear to be "upside down" (i.e.,
> "full scale" would read "zero", while "zero" would read "full scale"), this
> could easily explain the anomaly which Brian reported...
> 
> What I DON'T understand though, is how we could have possibly missed
> this while conducting our "final" lab tests...  Brian, is it possible that we failed
> to conduct any hot/cold tests after we introduced the new cables?  I realize
> that, by then, our focus had moved to sorting out phase switch glitches, etc...
> 
> Anyway, come Monday morning, we'll adjust the polarity of the TWINAX
> cables, check (and/or adjust) the calibration of the 16 amplifier boards; then
> run through a series of hot/cold tests to verify our changes...
> 
> INSTRUMENT STATUS...
> 
> At this point, the CCB is running in the Receiver Lab (as ccblab) with no input
> ports connected; although the receiver control cable is still attached. 
> 
> The "demo_client" was disabled at the end of our testing session; so the CCB
> should now be available on the network...
> 
> Randy
> 
> 
> 
> 
> 
>