--- In TekScopes@..., "Dennis Tillman" wrote:
>
> The 7104 that Dick is selling is the fastest analog scope ever made. By
> coincidence I took this CRT photo on mine yesterday which will give you an
> idea of what it is capable of. This is a 2GHz 350mV signal displayed on the
> 7104 with the identical plugins that Dick has in his 7104. The 7104 is
> spec'd at 1GHz. The gain at 2GHz is down by about 9X but there it is
> triggering and the waveform is clear as a bell.
>
>
>
> Dennis

Dennis,

You need to qualify that statement a bit. The 7104 is the fastest production conventional analog scope ever made. Key qualifiers: Production and Conventional.

The former Soviet Union built scopes for government use that were faster. As with their scan converter digitizers, the CRTs were very long (well over a meter), allowing low deflection angles. These were custom built and not sold outside of a few government labs. I have never seen one, but have heard accounts directly from former users. They did not have microchannel plates, so cameras were needed for single shot capture. The amplifiers were not DC coupled.

Iwatsu had a couple of models of scan converter based "analog scopes" that were faster as well. These are funny animals – in one sense they act like an analog scope, but the display is digital. No memory, and conventional scope trigger only (no view of the pre-triggered portion of the waveform). But they have color LCD displays with unique colors for each channel's trace. The scan converter requires much less deflection angle than a conventional human viewed CRT, the target being only a couple of millimeters high. Hence the exotic amplifier chain used in the 7104 is not required to drive it. They are still fast amplifiers however.

I believe Iwatsu made these through the late 1990s.

The Tek 519 also has 1 GHz BW, but is direct access (input drives the CRT, having no amplifiers) and weird deflection factors like 1.37 V/cm. The calibrated area of the CRT is only 2 divisions high, one on either side of ground. While these restrictions are very limiting, I have heard from users at EG&G that it actually has better vertical linearity that the 7104. I have never seen a working 519 and can not verify that statement, but I remember hearing that the linearity and thermal compensation in the 7104 are not as good as in other Tek lab scopes. Some tradeoffs needed to be made to design this wonderful scope.

Steve