Re: Searching for a Tek 7000 series scope

Sean Turner

Hi Dennis,

Keep in mind that the 7904A timebase is not be calibrated at 200 ps/div (see the note on the front panel above the trigger source controls). The 7B15 is really intended for use in the 7104 with a 7B10 timebase, so it's minimum time/div is 200 ps/div with 10x zoom. However, because it's such a fast timebase, triggering on that signal is easy. The 7B92A timebase will not cleanly trigger on the same signal. It will trigger, but it's much uglier.

The signal generator in question is my HP 8664A, 10 kHz-3 GHz, set for 1.1 GHz carrier. The frequency response dies quickly beyond that.

According to my calculation, the ~520 ps period shown originally at 200 ps/div corresponds to roughly 1.93 GHz as you mentioned. At 1.1 GHz, the period should be just slightly under 1 ns. If you look at the pictures I added to the album, you'll note that at 500 ps/div it's showing the correct period, but at 200 ps/div the signal seems to be getting compressed in the time domain. It should be quite a few more divisions at 1.1 GHz and sweep speed combo.

Still, it's very good performance and a testament to how well engineered this scope is. I can get a stable trigger up to about 1.43 GHz, at which point the amplitude is rolling off very fast.


On Sat, Apr 20, 2019 at 03:53 PM, Dennis Tillman W7PF wrote:

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 it to display that at one or two
divisions of vertical no matter what you did.

What I don't understand is what you had to do to get that 2GHz sinewave on the
screen of a 7904A with a just a 7A19. Also how hard was it to get the 7B15 to
trigger at that frequency? One last question: What was your signal source?

My complements to you for whatever you did to get your new scope to do that.
Everybody should sit up and take notice of what a 7901A can do. It would be
even faster with a 7A29 in it. You are certainly capable of putting this scope
to very good use.

Dennis Tillman W7PF

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