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All, I just wanted to wrap up and let you know where this ended up. My last post I was fighting an issue with the -15v rail. Now, when I started working on this scope, the -15 was fine. Sometime

Hi Sean, OK, I looked at the pictures. The third picture really caught my attention!!! My first reaction was "This is not possible". The bandwidth must be so far down at 2GHz that you would barely get

I think that offset-feedback loop is not affected by lack of sampling, so offset control is still functional (just as the input signal were always zero). Feedback signal enters the head at pins 2&B,

Hi Sean, Congratulations on capturing a 7904A - it is an astounding instrument. It was nice of John Griessen to offer you one of his scopes. Most of the scope carts that are wide enough for a four

One can also find three-shelf heavy-duty plastic carts that work well as ‘scope carts. I have one made by Rubbermaid on which I kept a Tektronix 575 for many years. DaveD Sent from a small flat

Sean, Good choice. The Tektronix model 204-2 ‘scope cart is made specifically for the 7000-series ‘scopes. It has five slots that hold spare plug-ins as well as a drawer that may be used to hold

Hi Reginald, How did you find out the operating hours and power up figures? I have an 11403A and there is nothing in the Utility Menus that would give me that kind of information. Just a wild guess

Harvey, Thanks for your thoughts. Right now I definitely don't have the floor space for a scope cart, but I'm planning a move in the near future and am looking at houses. One criteria is enough floor

Hi Nenad, I agree that the avalanche pulse alone is probably so slow that the clipping lines simply act as a shortcut. But how to explain the response to the Offset control? When you change Offset

Hi Sean, Where are you located? Dennis Tillman W7PF

Hi Albert, In my case (without the snap-off signal) the head sensitivity to input signal was zero. The explanation is in the structure of the strip line to which C52 and C54 are attached. This

I have a scope mobile cart that will hold a 7000 series scope (no, not for sale). Some observations: The scopemobile was designed to be a roll around home for a scope in a lab/facility that had a

I wanted to thank everyone for their replies, direct emails, and advice. After consideration of many kind offers, I ended up purchasing a 7904A + plugins from John Griessen. It arrived yesterday!

Hi Nenad, I overlooked your second last message in which you answered my question about DC response and more. I have to admit that I fail to understand what is exactly going on when R62 is

Whaw Nenad, what a good luck that you discovered the fault in S-

It's alive - sort of. I had to perform quite a bit of surgery on the guts. I found that the mounting posts on the big board that attaches to the right side RF module had broken loose from the board,

Heh, I just fixed it, it's working now. While probing all components inside S-4, I found that the bottom lead of R62 was cold soldered (the one soldered to the gold plated PCB strip), it snapped off

A termination would present the same issue of wear. I'm not going to be monitoring a data link 24x7, so I'll be connecting and disconnecting more often. My 11801 had 44,000 operating hours but was

Thanks for the responses. I think I'll skip that project. It's not something I need. I'm getting a custom 1 MHz version of Leo Bodnar's <40 ps rise time square wave generator for TDR work with a

If possible, position things so that the tip of the drill points up. Stray shavings will fall away from instead into the hole. Thanks, Barry - N4BUQ