On Sat, 13 Mar 2004 12:50:42 -0600, John Fields
wrote:

That's close enough to 50% that you should have no problem generating
and extracting a fifth harmonic.

Thanks, John. I'd have been surprised if having tweaked it for maximum
50:50 this still wasn't good enough (it's only a tiny bit out now).

If you've got the cap and resistor in series with the base, and no other
circuitry in there, then what you're doing is half-wave rectifying the
square wave in the base-to-emitter diode, and that's what you're seeing,
along with what looks like some AC at the fundamental riding on the
falling peaks and rising valleys of the square wave. The reason you
can't see the fifth harmonic is because it's far enough down that
everything else is so much higher in voltage that it's essentially down
in the mud. If you want the fifth out, you'll have to extract it using
a filter of some sort, the easiest being a series tuned trap or a
parallel tuned tank.

I've lashed up a 17.2Mhz BPF that should do the trick just fine. It'll
be a bit of a fiddle trying to hook it into the existing circuit but
I'll do my best.

Why don't you post your schematic so we can see exactly what you're
doing?

Will do....
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On Sat, 13 Mar 2004 12:50:42 -0600, John Fields
wrote:

Again, why don't you post a schematic of what you're up to? Please?-)

The schematic is now on abse....

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On Sat, 13 Mar 2004 12:50:42 -0600, John Fields
wrote:

Again, why don't you post a schematic of what you're up to? Please?-)

The schematic is now on abse....

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The BBC: Licensed at public expense to spread lies.

I read in sci.electronics.design that Reg Edwards
wrote (in
et.com) about 'Extracting the 5th Harmonic', on Sat, 13 Mar 2004:
Then along came Oliver Heaviside who turned the World upside down by
replacing jw with p.

I should probably change my name to Phon .oodgate in his honour. (;-)
--
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

I read in sci.electronics.design that Reg Edwards
wrote (in
et.com) about 'Extracting the 5th Harmonic', on Sat, 13 Mar 2004:
Then along came Oliver Heaviside who turned the World upside down by
replacing jw with p.

I should probably change my name to Phon .oodgate in his honour. (;-)
--
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 Sat, 13 Mar 2004 19:38:47 +0000, Paul Burridge
wrote:

On Sat, 13 Mar 2004 10:37:13 -0800, John Larkin
wrote:

On Sat, 13 Mar 2004 16:26:10 +0000, Paul Burridge
wrote:


Okay, I've now tweaked the osc. to get as near to 50% as possible.
Alas, still no sign of any 5th present in the multiplier's output.
Here's a shot of the (fundamental) output from the inverters. I can't
see any real problem with why it shouldn't be good for a reasonable
comb of harmonics, but our experts may know better. BTW, settings were
2V/div. and 0.1uS/div.

http://www.burridge8333.fsbusiness.co.uk/trace.gif



That waveform *has* bunches of 5th harmonic. All you need is a
properly functioning bandpass filter to pluck it out.

You must have bloody good eyesight, John! :-)

You can count the graticule lines fairly well; it's close to 50%, and
the edges are fairly fast. And no, in fact I have terrible eyesight.

BTW, can you recommend a sub nS Schmitt inverter that's easily
obtainable?

I don't know of any really fast Schmitts. An HC14 followed by an AC04
should have fast edges. My favorite thing like this is an OnSemi
NL37WZ16 with all three sections in parallel. Powered from +6 or so,
it puts 5 volts into 50 ohms in something like 750 ps.

The old original RCA AC-series parts were sub-ns - crude and rude,
they were - but some ACs are now a little slower to reduce ground
bounce.

Most of the LVDS-to-TTL LVDS line receivers make damned fine
comparators with sub-ns output edges.

For screaming edges, there's always the step-recovery diode, or a
medium-power gaasfet like the CLY2.

John

On Sat, 13 Mar 2004 19:38:47 +0000, Paul Burridge
wrote:

On Sat, 13 Mar 2004 10:37:13 -0800, John Larkin
wrote:

On Sat, 13 Mar 2004 16:26:10 +0000, Paul Burridge
wrote:


Okay, I've now tweaked the osc. to get as near to 50% as possible.
Alas, still no sign of any 5th present in the multiplier's output.
Here's a shot of the (fundamental) output from the inverters. I can't
see any real problem with why it shouldn't be good for a reasonable
comb of harmonics, but our experts may know better. BTW, settings were
2V/div. and 0.1uS/div.

http://www.burridge8333.fsbusiness.co.uk/trace.gif



That waveform *has* bunches of 5th harmonic. All you need is a
properly functioning bandpass filter to pluck it out.

You must have bloody good eyesight, John! :-)

You can count the graticule lines fairly well; it's close to 50%, and
the edges are fairly fast. And no, in fact I have terrible eyesight.

BTW, can you recommend a sub nS Schmitt inverter that's easily
obtainable?

I don't know of any really fast Schmitts. An HC14 followed by an AC04
should have fast edges. My favorite thing like this is an OnSemi
NL37WZ16 with all three sections in parallel. Powered from +6 or so,
it puts 5 volts into 50 ohms in something like 750 ps.

The old original RCA AC-series parts were sub-ns - crude and rude,
they were - but some ACs are now a little slower to reduce ground
bounce.

Most of the LVDS-to-TTL LVDS line receivers make damned fine
comparators with sub-ns output edges.

For screaming edges, there's always the step-recovery diode, or a
medium-power gaasfet like the CLY2.

John

"Mike Andrews" wrote in message
...
In
(rec.radio.amateur.homebrew), Paul Burridge wrote:
Hi all,

Is there some black magic required to get higher order harmonics out
of an oscillator?

The crystal osc itself, probably is sine wave, and therefore has low 5th
content.
Square it up, then pass through a filter, and moderate Q parallel resonant
tank on the 5th harmonic.

"Mike Andrews" wrote in message
...
In
(rec.radio.amateur.homebrew), Paul Burridge wrote:
Hi all,

Is there some black magic required to get higher order harmonics out
of an oscillator?

The crystal osc itself, probably is sine wave, and therefore has low 5th
content.
Square it up, then pass through a filter, and moderate Q parallel resonant
tank on the 5th harmonic.

On 13 Mar 2004 19:00:20 GMT, (Avery Fineman)
wrote:

[nostalgic history lesson snipped]
Quintuplers CAN be made, but, so far, Paul hasn't explained
enough specifics about his circuit, or how he is sensing any 5th
harmonic for any of us to get a good handle on a possible aid.

There's now the schematic of the relevant stages viewable on abse. If
there's anything else that's unclear, please feel free to ask for
clarification.

Note: Lacking any spectrum analyzer, a wide-range HF receiver
with an S meter can be an indicator...but such needs to be checked
against a calibrated signal generator for compensation of varying
S meter indication versus input levels. That's what I use for
checking HF levels (Icom R70) and it has been calibrated against
a reasonably-known-level RF source.

Len, you're a genius! I'd totally forgotten about that old dodge. Now
I have just the job in the attic: an aging Yaesu FT767GX that hasn't
been used for years, just lying around waiting to have its front end
blown up! :-)
Thanks!
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The BBC: Licensed at public expense to spread lies.