On 22 Mar 2004 13:06:44 -0600, mcalhoun wrote:

I tried to "reply", but your inbox was full!

Uh, it used to be ".invalid" but until I gat this blasted new
newsreader to allow me to use that, I dunno. Maybe example.org.
Maybe a sneakemail addy I can throw away when it gets spammed to
hell so at least some people can backchannel me for the real addy if
I think they need it.

....[snip]....
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge.

Hey Doc. Should that quote be attributed to you or what?

Yes, at least mostly, 'Way back when email first started (with long
strings of !...!...! in the addresses), I had "Three boxes..." (altho
I don't recall just which three). Shortly thereafter, someone suggested
a fourth box and someone else the fifth, and I was lucky enough to be
able to condense all five boxes into the one line I've used ever since.

--Myron.

Ok. Duly noted. Maybe Myron Calhoun, et. al. ?

--
Best Regards,
Mike

On 22 Mar 2004 13:06:44 -0600, mcalhoun wrote:

I tried to "reply", but your inbox was full!

Uh, it used to be ".invalid" but until I gat this blasted new
newsreader to allow me to use that, I dunno. Maybe example.org.
Maybe a sneakemail addy I can throw away when it gets spammed to
hell so at least some people can backchannel me for the real addy if
I think they need it.

....[snip]....
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge.

Hey Doc. Should that quote be attributed to you or what?

Yes, at least mostly, 'Way back when email first started (with long
strings of !...!...! in the addresses), I had "Three boxes..." (altho
I don't recall just which three). Shortly thereafter, someone suggested
a fourth box and someone else the fifth, and I was lucky enough to be
able to condense all five boxes into the one line I've used ever since.

--Myron.

Ok. Duly noted. Maybe Myron Calhoun, et. al. ?

--
Best Regards,
Mike

I tried to "reply", but your inbox was full!

....[snip]....
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge.

Hey Doc. Should that quote be attributed to you or what?

Yes, at least mostly, 'Way back when email first started (with long
strings of !...!...! in the addresses), I had "Three boxes..." (altho
I don't recall just which three). Shortly thereafter, someone suggested
a fourth box and someone else the fifth, and I was lucky enough to be
able to condense all five boxes into the one line I've used ever since.

--Myron.
--
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

On 13 Mar 2004 22:43:58 -0600, wrote:

Is there some black magic required to get higher order harmonics out
of an oscillator?
I'm only trying to get 17.2Mhz out of a 3.44Mhz source and am thus far
....[snip]....

John L. Reinartz, W1QP, published "A Fundamental-Reinforced Harmonic-
Generating Circuit" in the July, 1937, issue of QST. I don't have a
copy handy, but a followup article "Putting the Harmonic Generator to
Work" in the April, 1938, QST contains this statement:

"It will be remembered that in the harmonic-generator circuit the
crystal oscillator was operated on the crystal frequency only,
and that the following tube was used to generate the even and
odd harmonics up to the 11th and 12th. For our present purpose,
the 8th harmonic is sufficient; that is, 28 Mc. from an 80-meter
crystal...."

Hope this helps.

Five boxes preserve our freedoms: soap, ballot, witness, jury, and
cartridge.

Hey Doc. Should that quote be attributed to you or what?

--
Best Regards,
Mike

Paul Burridge wrote in message . ..
Hi all,

Is there some black magic required to get higher order harmonics out
of an oscillator?
I'm only trying to get 17.2Mhz out of a 3.44Mhz source and am thus far
failing spectacularly. I've tried everything I can think of so far to
no avail.

C2's small size (3.3pF)is attenuating any 5th harmonic current by 6db
into
Q2's base biasing network, in both posted versions.

Biasing the first stage as classC in the second revision is a pretty
drastic change from the previous class A revision (100mW). Don't you
believe in tiny steps?

By the way, when you post a waveform where traces are only identified
by node numbers, when the schematic provided is an image only, there's
no way we can know where the traces originate, unless you tell us.

RL

On 14 Mar 2004 10:01:00 -0800, (R.Legg) wrote:

C2's small size (3.3pF)is attenuating any 5th harmonic current by 6db
into
Q2's base biasing network, in both posted versions.

Curious. Can you show some figures to back this claim up? (Not that I
don't believe you; just that I'd like to see how you arrived at this
view).

Biasing the first stage as classC in the second revision is a pretty
drastic change from the previous class A revision (100mW). Don't you
believe in tiny steps?

I've been trying nothing else *but* "tiny steps" for the last few
days. There's no harm in the ocassional quantum jump. :-)

By the way, when you post a waveform where traces are only identified
by node numbers, when the schematic provided is an image only, there's
no way we can know where the traces originate, unless you tell us.

My apologies. I'll try not to let it happen again.
--

The BBC: Licensed at public expense to spread lies.

Paul Burridge wrote in message . ..
On 14 Mar 2004 10:01:00 -0800, (R.Legg) wrote:

C2's small size (3.3pF)is attenuating any 5th harmonic current by 6db
into
Q2's base biasing network, in both posted versions.

Curious. Can you show some figures to back this claim up? (Not that I
don't believe you; just that I'd like to see how you arrived at this
view).

The reactance of the C2 part is almost 3K at the fifth harmonic.

Input impedance of the biasing network is 300 ohms - this is about
half the small signal input impedance of the 3904 @4mA.

Even with bypassed emitter, only 1/3 of C2's AC current will enter the
base of Q2.

If the resonant circuit used lower L and higher C values, C2 could be
increased without as severe an effect as it has here.


Biasing the first stage as classC in the second revision is a pretty
drastic change from the previous class A revision (100mW). Don't you
believe in tiny steps?

I've been trying nothing else *but* "tiny steps" for the last few
days. There's no harm in the ocassional quantum jump. :-)

As previous posters have stated, if the input is squarish then the
harmonics are already there.

There is a +/- 3% window on all the optimum duty cycles (ie 10, 30,
50, 70, 90%), including risetime, for which the 5th harmonic amplitude
is relatively constant, at about 10% of the initial peak amplitude.
Note that the 30/70% period is a median quasi-minima for both 3rd and
4th harmonics, possibly reducing LF filtering problems in the first
stage, as the 1st and 2nd are farther away. 50% being available, you
should stick to it.

I don't know if you're doing any actual physical breadboarding. The
100mW power dissipation suggests not. Pre-apps it's time.

If this is a physical breadboard, then perhaps you might let us know
what you are actually using for your 2uH inductors. You wouldn't want
the relatively hefty classA bias to have any effect on them, so there
should be a lot of air in their flux path - not a couple of turns on a
bead, I hope.

RL

On 14 Mar 2004 23:43:57 -0800, (R.Legg) wrote:

The reactance of the C2 part is almost 3K at the fifth harmonic.

Input impedance of the biasing network is 300 ohms - this is about
half the small signal input impedance of the 3904 @4mA.

Even with bypassed emitter, only 1/3 of C2's AC current will enter the
base of Q2.

Understood. I chose a very low value for C2 because it was the third
harmonic that was dominating and most needed cutting down to size.
Though the reactance at the fifth is high, it's a lot higher still at
the third. Although I suppose I could have used a simple series L/C
tuned circuit tuned to pass on the fifth and attenuate everything
else. Do you think that might work?

If the resonant circuit used lower L and higher C values, C2 could be
increased without as severe an effect as it has here.

Good point.

As previous posters have stated, if the input is squarish then the
harmonics are already there.

Theoretically, perhaps! Damned if I can find the 5th, though.

There is a +/- 3% window on all the optimum duty cycles (ie 10, 30,
50, 70, 90%), including risetime, for which the 5th harmonic amplitude
is relatively constant, at about 10% of the initial peak amplitude.
Note that the 30/70% period is a median quasi-minima for both 3rd and
4th harmonics, possibly reducing LF filtering problems in the first
stage, as the 1st and 2nd are farther away. 50% being available, you
should stick to it.

I'm as close to 50% as I can get. If square waves are so finicky about
producing the 5th if their mark/space ratios are a tiny bit out then
maybe I need to consider some other way of generating such harmonics.

I don't know if you're doing any actual physical breadboarding. The
100mW power dissipation suggests not. Pre-apps it's time.

I'm using my 'leopardboard' technique: a layer of PCB with liittle
island pads etched out in copper and component ends soldered to those
islands.

If this is a physical breadboard, then perhaps you might let us know
what you are actually using for your 2uH inductors. You wouldn't want
the relatively hefty classA bias to have any effect on them, so there
should be a lot of air in their flux path - not a couple of turns on a
bead, I hope.

Nope. They should be okay. 5mm dia, air-core, 20mm winding length
--

The BBC: Licensed at public expense to spread lies.

On 14 Mar 2004 23:43:57 -0800, (R.Legg) wrote:

The reactance of the C2 part is almost 3K at the fifth harmonic.

Input impedance of the biasing network is 300 ohms - this is about
half the small signal input impedance of the 3904 @4mA.

Even with bypassed emitter, only 1/3 of C2's AC current will enter the
base of Q2.

Understood. I chose a very low value for C2 because it was the third
harmonic that was dominating and most needed cutting down to size.
Though the reactance at the fifth is high, it's a lot higher still at
the third. Although I suppose I could have used a simple series L/C
tuned circuit tuned to pass on the fifth and attenuate everything
else. Do you think that might work?

If the resonant circuit used lower L and higher C values, C2 could be
increased without as severe an effect as it has here.

Good point.

As previous posters have stated, if the input is squarish then the
harmonics are already there.

Theoretically, perhaps! Damned if I can find the 5th, though.

There is a +/- 3% window on all the optimum duty cycles (ie 10, 30,
50, 70, 90%), including risetime, for which the 5th harmonic amplitude
is relatively constant, at about 10% of the initial peak amplitude.
Note that the 30/70% period is a median quasi-minima for both 3rd and
4th harmonics, possibly reducing LF filtering problems in the first
stage, as the 1st and 2nd are farther away. 50% being available, you
should stick to it.

I'm as close to 50% as I can get. If square waves are so finicky about
producing the 5th if their mark/space ratios are a tiny bit out then
maybe I need to consider some other way of generating such harmonics.

I don't know if you're doing any actual physical breadboarding. The
100mW power dissipation suggests not. Pre-apps it's time.

I'm using my 'leopardboard' technique: a layer of PCB with liittle
island pads etched out in copper and component ends soldered to those
islands.

If this is a physical breadboard, then perhaps you might let us know
what you are actually using for your 2uH inductors. You wouldn't want
the relatively hefty classA bias to have any effect on them, so there
should be a lot of air in their flux path - not a couple of turns on a
bead, I hope.

Nope. They should be okay. 5mm dia, air-core, 20mm winding length
--

The BBC: Licensed at public expense to spread lies.

Paul Burridge wrote in message . ..
On 14 Mar 2004 10:01:00 -0800, (R.Legg) wrote:

C2's small size (3.3pF)is attenuating any 5th harmonic current by 6db
into
Q2's base biasing network, in both posted versions.

Curious. Can you show some figures to back this claim up? (Not that I
don't believe you; just that I'd like to see how you arrived at this
view).

The reactance of the C2 part is almost 3K at the fifth harmonic.

Input impedance of the biasing network is 300 ohms - this is about
half the small signal input impedance of the 3904 @4mA.

Even with bypassed emitter, only 1/3 of C2's AC current will enter the
base of Q2.

If the resonant circuit used lower L and higher C values, C2 could be
increased without as severe an effect as it has here.


Biasing the first stage as classC in the second revision is a pretty
drastic change from the previous class A revision (100mW). Don't you
believe in tiny steps?

I've been trying nothing else *but* "tiny steps" for the last few
days. There's no harm in the ocassional quantum jump. :-)

As previous posters have stated, if the input is squarish then the
harmonics are already there.

There is a +/- 3% window on all the optimum duty cycles (ie 10, 30,
50, 70, 90%), including risetime, for which the 5th harmonic amplitude
is relatively constant, at about 10% of the initial peak amplitude.
Note that the 30/70% period is a median quasi-minima for both 3rd and
4th harmonics, possibly reducing LF filtering problems in the first
stage, as the 1st and 2nd are farther away. 50% being available, you
should stick to it.

I don't know if you're doing any actual physical breadboarding. The
100mW power dissipation suggests not. Pre-apps it's time.

If this is a physical breadboard, then perhaps you might let us know
what you are actually using for your 2uH inductors. You wouldn't want
the relatively hefty classA bias to have any effect on them, so there
should be a lot of air in their flux path - not a couple of turns on a
bead, I hope.

RL