Hello Paul, >> Now to come back on the EMC subject, the same parallel problems exist with >> CENELEC. >> They don't have to justify they're action, they impose CE rules with >> different requirements than other countries. >> WHY? >> What justify this?
Paul, emission standards you have to meet are actually about the _same_ as other countries. Even in countries without standards published, the customers require compliance either with CISPR-22 (the same as EN 55022) or FCC Part 15, Class B, and some of those countries (such as Australia) have adopted CISPR-22 requirements as their own standard, too. >> How to get rid of this superior behaving people and have them use >> existing rules? You are doing that in your meetings with BIPT. It is possible that their reaction is not so good -- but people only scratch after the flea bites, no? >> If nobody complains, if nobody take the attention to this situation, >> if nobody put pressure on those guy's, nothing will change and the >> industry will remain the junk of those guy's with one common sense: >> PAY the cost. This is a basic problem in relations between industry and government, everywhere. >> So I'm looking for cheap pre-compliance measuring equipment. Not the >> conventional ones who are overpriced (even second hand). >> To start: >> Did anybody use a scanner (+/- $US 700) as mesuring receiver? >> It's computer controllable, has a wide frequency range, is sensitive. I have several receivers (some cost more than US $700) and I think they could be useful, but you should understand that the amplitude calibration is not all that good. If you are talking about 10 dB, it's probably OK. If you are talking about 3 dB I find neither the ICOM R7000 nor the ICOM R7100 to be able to give the kind of fine discrimination needed. However, I have notattempted to use the R7100's data output as a level meter. If you do this, it may have enough steps to be if use -- but do remember that calibration on these receivers may change when you change frequency bands. Also, bandwidth is only approximately the same as the 120 KHz required for emissions testing and 9 KHz for conducted emissions (WFM and WAM modes). This means response to broadband signals will differ from a set using the right filters. You will also not be able to use a quasi-peak detector (unless you build one external to the receiver). I also have some wide-range hand-held scanners and Amateur Radio portable transceivers which are useful in locating the places from which radio signals are being emitted. One transceiver (which has wide receiving coverage) is smaller than a pack of cigarettes, including antenna. Using such a device means I do not have to carry a spectrum analyzer out to my equipment table for probing, but it's not always satisfactory. Sometimes I still must use a spectrum analyzer instead. I will note that the R7000 and R7100 do not as sold receive frequencies below 25 MHz, and would be of limited use for conducted emission reading. I have equipped my R7000 with an up-converter made by a British company, so it is able to receive about 0.1 - 2000 MHz. Sensitivity at the low end is not as good as it is higher up. This has to be taken into account when measuring signals in that range. The Yupiteru 7100 and AOR 8000 hand-held receivers cover (with reduced sensitivity) down to 0.5 MHz and are capable of being set at lower frequencies where they may or may not work. The AOR has a magnetic antenna built-in which could confuse measurements taken with it at low frequencies. Their amplitude levels are not so easy to read, though. >> Did anybody design an antenna for 30 - 200 or/and 200 - 1000 MHz range? You can easily build antennas which will work over these ranges. However, calibrating a wide-band antenna so that its antenna factor is known, is not all that easy. You also ned a signal source of a steady level and wide frequency coverage. Then, if you can borrow an antenna with a known antenna factor at ranges you expect to use, you can compare signals received with each one and thereby establish a calibration for your antenna at your measurement site. This calibration is not good anywhere else, though. The "Roberts dipole" design, named after the USA Bureau of Standards engineer who first built them, is published in some of our commercially available EMC guides and magazines, and you could build this one yourself. The advantage to this is that with reasonable construction, its calibration may be assumed from its dimensions. The problem is, you will then have to change dipole length as you go through the test -- and a 30 MHz diole is 5 meters long. Also, using a dipole close to the EUT may throw off the readings. >> Did anybody made a LISN? There's no reason you can't do this. And... you don't need a BIPT license for it. Anything you can make that will couple RF out of the power cord for measurement will do the job if you have some way to compare it to what a LISN will produce. Paul, one company I worked at had only a screen room, a LISN, an old HP 141T spectrum analyzer mainframe and two plug-ins (cost for this today in the USA about $3000) and some antennas. In spite of this, we were able to pre-test and design our equipment so it almost always met emission standards on the first try. Emissions are relativiely easy to measure. Radiated and conducted immunity really can'tbe tested without specialized and costly test equiment, but I recall one place did a crude pretest using a "Jacob's Ladder" high-voltage arc generator as an RF and impulse source. The certification test _must_ be done with the right waveforms, levels and field strength. There's no getting around this. Cheers -- and Happy New Year. Cortland
