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Re: A scoping question

Hi Finn,

	Very happy to here you fiber probes are ready to go ;-)

I think you will find the Tektronix scope to be very well behaved and it
will do exactly what you need.  Triggering in tough situations is easy for
this scope.  It is just such situations that separate Tektronix scopes from
those "other guys" ;-)

I will be very interested in hearing how this goes!

Cheers,

	Terry


At 10:59 PM 12/08/1999 +0100, you wrote:
>I am going to try my new rotary out on sunday, and since the coil is
>permanently situated at the museum 50 miles away, I want to be well
>prepared, since I can`t just run back to the workshop and fix something
>up.
>
>To monitor the primary capacitor voltage, I will use the fiber probes,
>with the 50kV transducer across the cap, and in order to get all 3
>breaks displayed relative to 50 Hz, I must trigger on the primary
>voltage into the pig, right? (this will be with the 500V transducer and
>the other channel of the receiver).
>
>I will then adjust the electrodes for equal bang size.
>
>However, with the lowly Gould 20 MHz scope, That I have been using up to
>now, I have had problems locking on to the slow 50 Hz signal, while the
>coil was running. This was sensing the secondary field with a small
>antenna (but it survived being 4 meters away from the coil).
>
>I now have a Tektronix 485 (350 MHz), which I bought because I assume
>that such a great analogue scope would have better ability to lock to a
>slow signal. (This is all something that I have heard, I have little
>experience in this field).
>I have about 10 meters of optic fiber cable, so the scope can be
>situated safely in the trunk of the car, that long away from the coil,
>but the question is this, should I expect the scope to be able to
>trigger on the 50 Hz signal at one channel, in the presence of a 100kHz
>signal on the other channel, or do I have to make some sort of pulsing,
>or a square wawe at 50 Hz, to enable the scope to sync reliably on 50
>Hz? And if, how do I convert a sine wawe to square in a simple fasion
>(there is little time, now)?
>
>I have rather great expectations to this scoping event, since the scope
>has a delayed sveep function, allowing me to focus into part of the
>signal, I imagine a shot, where i see the top trace documenting the
>positioning of the breaks relative to the 50 Hz signal on the bottom
>trace, and then a zoom in on one of the ringdowns, hopefully displaying
>details about whatnotch quenching is occurring. Would be quite an
>informative screendump, if I manage to capture it on film from this
>analogue scope.
>
>Cheers, Finn Hammer
>