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Sure...my RMX 1450 is 45 pounds in it's case..

In trying to find out what John is doing, I was brushed off..

There is some equip here I could glom, but don't know if it's any better or worse than what JC has. No info has been forthcoming from JC to determine the relative merit of the equip I have access to.

I want to characterize the equipment for the task, but wanted to know how JC did such for his setup, only to find he didn't.

I resigned myself to designing up an IA setup, using the CMMR of the device to null out the drive and cable signals, but find that the resistors TCR makes the circuit very sensitive to thermal variations on the order of bout half a degree. So, started work on a thermally controlled plate in an insulated package, with the intent of keeping temp variations down to about a tenth of a degree or better. (at work, they typically measure to within a millikelvin)
And, I am also wrestling with the fact that the cable under test forms a ground loop, and how to keep the shield resistance differences from altering the response of the setup..

Then summer hit, and I hit the road for a show here called wiz bang. 'Taining about 1000 people every sunday, this sunday the last of the year.. Then I can get back to play..

So, although it seems that just pluggin the stuff in should work, there are quite a few gotcha's that will throw the measurement off, and some of those gotcha's will be cable specific and repeatable, while actually artifacts of something that is not being accounted for..

""Which one of us will have some real results first?""peter

You, my guess...I'm gutting a kitchen to put up s'rock, cabinets, and tile floor..leaving about 30 minutes at lunchtime every day for play, when I'm not jogging or swimming.


""Since you could clearly set this up with a lot more care than JC, given your far greater expertise, this should be child's play for you.""peter

The detail required for this measurement is not child's play. And my "expertise" is in getting smacked in the face with the fine detail things not accounted for. Hence my desire to actually understand the test equipment and it's weaknesses. and to explain those weaknesses to all.

Cheers, John




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  • Sure...my RMX 1450 is 45 pounds in it's case.. - jneutron 10:21:06 08/22/03 (3)


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