I have an EMI problem with a high speed system. There is a pair of wires which are taken from a high speed driver to a high impedance electrostatic plate which resides in a vacumm. The plate is enclosed in a metal enclosure so does not emit, but the wires do. They are an untwisted pair about 4 inches of which is exposed, between 2 metal boxes. The signal on the wires is about 500 volts with a 1 nanosecond rise time and about 48 khz repetition rate. The rise time may not be compromised.I have tried coax type shielding, but this slows down the rise time. I was thinking the next step is a rigid conduit about 2 inch diameter, which may have a higher impedance/lower capacitance than a coax. Also, twisted pair is worth trying, but again I cannot afford to slow down the signal.

Hello Geoff,That sure looks like a trip to the next big hardware store. If you are lucky they might even have 2" copper pipe. See if 1" would do the trick, it's much easier to obtain. Sometimes they carry decorative brass tubing of almost 2" but that stuff is expensive (it looks cool though).Regards, Joerg

Any transmission line experts?

Mar 02, 2006 22 Replies

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Michael A. Terrell 20 years ago

Which was soon replaced by the Alexanderson Generator.

Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida

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Geoff C 20 years ago

"Dave (from the UK)" wrote in news:44081a1d@212.67.96.135:

My load is capacitive, that is unavoidable 'cos its a type of deflection plate. I'd like to know what the effect of twisted pair is on the Zo as apposed to parallel conductors.

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Joseph2k 20 years ago

At the same spacing twisted versus parallel is the same.

JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller

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