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Strategies & Market Trends : 2026 TeoTwawKi ... 2032 Darkest Interregnum -- Ignore unavailable to you. Want to Upgrade?

To: maceng2 who wrote (49237)	4/26/2009 1:35:27 PM
From: Haim R. Branisteanu	Read Replies (1) \| Respond to of 217688

thanks I am familiar with the phenomena but did not know it is now called "ringing"

To: maceng2 who wrote (49237)	4/26/2009 1:42:27 PM
From: elmatador	Read Replies (1) \| Respond to of 217688

Power supplies generate spurious frequencies. I'm not sure but it may refer to a system oscillating. When I was microwave engineer, (in my days of analog technologies), if a power supply was badly designed, it would generate spurios frequencies. We had a problem once. I did the donkey work. The engineers would analyse. It went like that: Changed a part. 'swept' the base band with a level meter. Change a cable and swept the based band again. From 60Khz to 4.0Mhz slowy, (960 telehone channels) very slowy to see if a I could get spurious frequencies. They were there at all time spaced by a certain freq. (which was the problem), recorded and gave to the engineers. They ran out of ideas. I took a Sunday at a microwave station while the engineers were home (I was pole climber learning) and was learning about modulation. I thought we were having intermodulation. No one would believe if I would have said. I brought all parts from a new site to be installed. Brought sandwiches, coke, pencil, labels and cigarettes. Then I conducted an experiment: Since they have already changed all active parts and cables, I decided to change EVERYTHING. Starting from the bottom up. The power supplies were at the bottow, one operating, one standing by. I started with them. I kept only one working. Swept the Base band. Spurious were there. The first power supply I exchanged the spurious were not there. I stopped went out smoked one cigarette. It could not be possible it was the cause at the first try. Labelled. Put the original one. Spurious were back. Labelled. Put the two old. Problem returned. Put new one. Problem was away. Recorded. Went to hotel. Called S. Paulo and said: "Talk to the fatory. We send the power supply. They will surely will replicated the problem there. They said to me wait for them to see. I replicated the experiment. It was solved. Those spurious frequencies- generated by the power supplies (which feeds all the DC voltage of the system inside the rack)- would modulate the Local Oscilators and created freq. products that would appear inside the baseband (the band used for telephony traffic). They re-designed which had to be better shielded, the power supplies' components changed for better specs power transistors, made better grounding contacts.