From: Marco Denicolai
Date: Tue, 10 Jul 2001 14:18:48 +0300
Subject: Re: [TSSP] Toroid breakdown voltage indirect meas.
Hi Paul, I got the CCPS "almost" repaired. That means that the damaged driver works, but it gets warmer than the others and its performance is slightly lower. I can't find right now the cause, but I have become a kind of fatalist with these things: if it's a major problem, it will eventually cause a fault and then it will reveal itself. In the mean time, I added the second strike rail to Thor for a resulting: secondary diameter: 400 mm original strike rail diameter: 1300 mm added strike rail diameter: 860 mm strike rails (both) elevation from the primary: 150 mm I also added a sharp bump to the toroid. Now, as soon as the RSG starts triggering (around 10 kV), I also get streamers from the bump. I think that the streamers I get now at full power are much thinner than what I got without the bump, while their length is almost unchanged (max 3 meters). Tonight or tomorrow I'll measure secondary base current and (indirectly) voltage. Current with a Pearson current probe (model 110A, calibrated a few months ago, reads "High bandwidth", 0.1V/A) and voltage with the "flying" scope probe. The Pearson current probe has got a N coax connector, but I use a N-to-BNC adapter and a length of about 4 m shielded cable (I guess is a 50 ohm one). The probe should have a 3 dB attenuation @ 20 MHz, if I get it right from http://www.pearsonelectronics.com/Pages/Standard_Currrent_Monitors.html. Questions from you RF measuremnt guys: - should I set my scope input impedance to 50 ohms (to have a correct termination) and then multiply my reading by 2? Best Regards Paul wrote: > > Marco Denicolai wrote: > > > I could place a current transformer on the secondary grounding, > > then a length of 50 ohm coax to the memory scope. > > Do you know the frequency response of the CT, up to say 3MHz? > > Instead of the CT, a current shunt of around 1 ohm would provide > a nice flat-response feed to the coax. The test need only be done > at low voltage. > > Hope the CCPS repairs go OK - tricky stuff. > > Cheers, > -- > Paul Nicholson, > Manchester, UK. > -- -- _____________________________________________________________ Marco Denicolai Senior Design Engineer Tellabs Oy tel: +358 9 4131 2769 DSL Products mobile: +358 50 353 9468 Sinikalliontie 7 fax: +358 9 4131 2410 02630 Espoo FINLAND email: marco.denicolai@tellabs.com _____________________________________________________________
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.