On Wed, 17 Mar 2004 12:03:04 +0000, Paul Burridge
wrote:


Okay, well at least I can see this one! Not sure about the SA trace,
though. Came out clearly enough but I'm not sure what you were trying
to prove by it.

---
It's an FFT of what's coming out of Larkin's suggested two-stage
bandpass filter.

The first vertical marker (f1) goes through the first peak, 17.19MHz,
which proves the fifth is in a 3.44MHz square wave. The second marker
goes through 34.38, so so's the tenth.
---

As for the 'scope traces, there doesn't seem to be any
phase correlation between the two and you don't indicate at what point
the probe was inserted.

---
Are you kidding? Count the high frequency cycles between the first
leading edge and the same point on the second leading edge of the square
wave and you'll find there are exactly five.
---

The square wave r/f slopes look a bit tardy,
too.

---
That's because the generator wasn't isolated from the filter and you're
seeing the filter's input dragging it around.
---

What was the active device you used to generate them?

---
Tektronics FG502. Here's the layout:



[TEK FG502]-+-[BPF]-+-[TEK 2465A]---[HP5328A]
| |
| +-[HP54602B]
|
[TEK DC504]



--
John Fields