Re: 7603 CRT max possible bandwidth?

Don Black <donald_black@...>

Thanks Dennis, the 7109 was a typo, meant 7104 (that sounds better than senior moment ;) ). I was aware of the examples of higher bandwidth special amplifiers using the 7104 and the trade off of frequency at the expense of bad transient response. However it's good to see your more detailed description. I thought some of the foreign GHz scopes might have been direct view but you may be right about them all being coupled to readout tubes. I guess the old 519C was direst view without any MCP.
It would be interesting to know what they used the modified 3GHz 7104 system for. If it was impulse work the poor transient response would seem significant (I wonder if they could analyze the results and allow for the pulse distortion)? If it was just frequency response then something like a sampling scope or spectrum analyzer would seem better. Perhaps they just did it to prove they could (higher, faster, stronger).

Don Black.

On 13-Jul-13 2:57 PM, Dennis Tillman wrote:

Hi Don,


There was no 7109. But you may be thinking of something B&H Engineering (Bernie and Harvey Horowitz, Monroe, NY) made. They modified a Tek 7104 to take advantage of the exquisite 1 V/Div vertical deflection sensitivity of the 3GHz CRT. The did this by removing the entire vertical interface, differential delay line, and vertical amplifier and replacing it with a single ended connection using a proprietary 3GHz amplifier module they developed.


They designed two vertical amplifier plugins for it. The M2000 was a 3GHz, 50 ohm plugin and the M3000 was similar except it had a variable delay feature. The output of both plugins was single ended and coupled to the mainframe using a SMB connector. The heart of these two plugins is a single module made from discrete parts for amplification, the 3002, which they designed and sold. The module was not Gaussian. It had terrible overshoot and ringing.


They don’t remember if they made 2 or 3 complete systems for the Navy. I have one of each of the vertical plugins. I met with them last month to learn the fate of the mainframes in hopes I could get one donated to the VintageTEK museum but they were given to the Navy for whom they were developed and lost track of them.


From the exterior, the 7104 they modified looks exactly like a conventional 7104. If you open one up it would become immediately obvious that the vertical amplifier was removed and replaced with a 2” x 2” module which directly drove the vertical deflection plates.


There is no way to verify their claim that this scope was capable of 3GHz. The technology to do that didn’t exist in a form that a small company of their size could afford at that time. Even Tek was unable to confirm the performance of the CRT beyond 3GHz.




From: Don Black, Sent: Friday, July 12, 2013 8:00 PM

I don't think that's what I had in mind. I believe there was mention of it several years ago here when there was discussion of the 7109, third party amplifiers and pushing it's bandwidth to 3 GHz. It might have been discussion around the old 519 without amplifiers, just talking about the tube frequency limit. Does anyone else remember it or are the pixies playing with my mind?

Don Black.

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