I read in sci.electronics.design that John Larkin jjlarkin@highSNIPland
THIStechPLEASEnology.com wrote (in lr1c50ls8v4stqisn34rcd8eoc4bkqu4vo@
4ax.com) about 'Extracting the 5th Harmonic', on Mon, 15 Mar 2004:
spam.yuk wrote:

I read in sci.electronics.design that John Larkin jjlarkin@highSNIPland
THIStechPLEASEnology.com wrote (in qvrb50hvn0t1nj7kq5cako00bjrtis7nnr@
4ax.com) about 'Extracting the 5th Harmonic', on Mon, 15 Mar 2004:
On Sun, 14 Mar 2004 21:27:21 +0000, Paul Burridge
wrote:

On Sun, 14 Mar 2004 12:04:18 -0800, John Larkin
wrote:


Why not just bandpass filter the 5th from the square wave? Too simple?

I suggested this a while ago, but no one seemed very keen on that
solution for some reason.

Write down their names for me please, so I can remember to not hire
them.

The reason no-one seemed keen is that the OP's **complaint** was that
his 5th harmonic BP filter didn't produce any output.


So I guess Fourier was wrong; makes sense, with a French name like that.

No, what has emerged from the discussion is that rather small deviations
from a perfect square waveform can drastically reduce the amount of one
or more harmonics in the spectrum, and this probably is the source of
the problem.

--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

On Mon, 15 Mar 2004 20:03:24 +0000, John Woodgate
wrote:


No, what has emerged from the discussion is that rather small deviations
from a perfect square waveform can drastically reduce the amount of one
or more harmonics in the spectrum, and this probably is the source of
the problem.

Either that, or a mistuned filter.

John

On Mon, 15 Mar 2004 20:03:24 +0000, John Woodgate
wrote:


No, what has emerged from the discussion is that rather small deviations
from a perfect square waveform can drastically reduce the amount of one
or more harmonics in the spectrum, and this probably is the source of
the problem.

Either that, or a mistuned filter.

John

On Mon, 15 Mar 2004 19:05:02 +0000, John Woodgate
wrote:

The reason no-one seemed keen is that the OP's **complaint** was that
his 5th harmonic BP filter didn't produce any output.

Eh?? Where did you get that from? I haven't even tried filtering yet!
I still haven't exhausted all the other suggestions made during the
course of this thread.

I think we have to supplement 'Read The Fascinating Manual' with 'RTCT'
- 'Read The Copulating Thread'.

Perhaps you should...
--

The BBC: Licensed at public expense to spread lies.

On Mon, 15 Mar 2004 19:05:02 +0000, John Woodgate
wrote:

The reason no-one seemed keen is that the OP's **complaint** was that
his 5th harmonic BP filter didn't produce any output.

Eh?? Where did you get that from? I haven't even tried filtering yet!
I still haven't exhausted all the other suggestions made during the
course of this thread.

I think we have to supplement 'Read The Fascinating Manual' with 'RTCT'
- 'Read The Copulating Thread'.

Perhaps you should...
--

The BBC: Licensed at public expense to spread lies.

On Mon, 15 Mar 2004 20:03:24 +0000, John Woodgate
wrote:

No, what has emerged from the discussion is that rather small deviations
from a perfect square waveform can drastically reduce the amount of one
or more harmonics in the spectrum, and this probably is the source of
the problem.

Not this particular problem, it isn't!

--

The BBC: Licensed at public expense to spread lies.

On Mon, 15 Mar 2004 20:03:24 +0000, John Woodgate
wrote:

No, what has emerged from the discussion is that rather small deviations
from a perfect square waveform can drastically reduce the amount of one
or more harmonics in the spectrum, and this probably is the source of
the problem.

Not this particular problem, it isn't!

--

The BBC: Licensed at public expense to spread lies.

On Mon, 15 Mar 2004 23:00:49 +0000, Paul Burridge
wrote:

On Mon, 15 Mar 2004 19:05:02 +0000, John Woodgate
wrote:

The reason no-one seemed keen is that the OP's **complaint** was that
his 5th harmonic BP filter didn't produce any output.

Eh?? Where did you get that from? I haven't even tried filtering yet!
I still haven't exhausted all the other suggestions made during the
course of this thread.

---
What???

According to your schematic, the input to R1 is a 2.16MHz square wave
and L1VC1 is a parallel tuned tank, (filter) tuned to 10.8MHz. So is
L2VC2C7. If you're not trying to do any filtering, what are those tanks
doing in there?

--
John Fields

On Mon, 15 Mar 2004 23:00:49 +0000, Paul Burridge
wrote:

On Mon, 15 Mar 2004 19:05:02 +0000, John Woodgate
wrote:

The reason no-one seemed keen is that the OP's **complaint** was that
his 5th harmonic BP filter didn't produce any output.

Eh?? Where did you get that from? I haven't even tried filtering yet!
I still haven't exhausted all the other suggestions made during the
course of this thread.

---
What???

According to your schematic, the input to R1 is a 2.16MHz square wave
and L1VC1 is a parallel tuned tank, (filter) tuned to 10.8MHz. So is
L2VC2C7. If you're not trying to do any filtering, what are those tanks
doing in there?

--
John Fields

On Mon, 15 Mar 2004 23:00:49 +0000, Paul Burridge
posted this:

On Mon, 15 Mar 2004 19:05:02 +0000, John Woodgate
wrote:

The reason no-one seemed keen is that the OP's **complaint** was that
his 5th harmonic BP filter didn't produce any output.

Eh?? Where did you get that from? I haven't even tried filtering yet!
I still haven't exhausted all the other suggestions made during the
course of this thread.

I think we have to supplement 'Read The Fascinating Manual' with 'RTCT'
- 'Read The Copulating Thread'.

Perhaps you should...

Errr... I read the thread. And in your first message you say. "All I
can get apart from the fundamental is a strong third harmonic on 10.32Mhz,
regardless of what I tune for. I've tried passing the osc output through two
successive inverter gates to sharpen it up, but still nothing beyond the third
appears after tuned amplification for the fifth."

If I'm not mistaken, "tuned amplification" IS "filtering".

Jim