Nice of John to make that offer!

You bet! MaCom is no HP however, and their "data sheets" are awfully skimpy.
I can almost put money on losing at least one finding out how sturdy they
are.

As for background and theory, I'll make copies of an artcile or two to
send you, about the discovery of the effect and the optimization of
diode structure to enhance it.

Will appreciate that as well Tom. I don't have to know the physics to make
use of the device, but it's helpful to have that insight when you're trying
to optimize the circuitry.

W4ZCB

Nice of John to make that offer!

You bet! MaCom is no HP however, and their "data sheets" are awfully skimpy.
I can almost put money on losing at least one finding out how sturdy they
are.

As for background and theory, I'll make copies of an artcile or two to
send you, about the discovery of the effect and the optimization of
diode structure to enhance it.

Will appreciate that as well Tom. I don't have to know the physics to make
use of the device, but it's helpful to have that insight when you're trying
to optimize the circuitry.

W4ZCB

On 13 Apr 2004 10:44:19 -0700, (Tom Bruhns) wrote:

Hi Harold,

Nice of John to make that offer!

As for background and theory, I'll make copies of an artcile or two to
send you, about the discovery of the effect and the optimization of
diode structure to enhance it. I suppose that the effect you're
seeing with the Schottkys is almost entirely capacitive stored charge,
and that won't "sweep out" of the diode with the sharp step you get
with a step-recovery diode. The articles I'll send have info about
efficiency, which can be surprisingly high considering the high order
of multiplication.

What's a sensible target for the multiplication factor using diodes
from say a 4Mhz source? I'd be nice to go straight to say 20X on
account of the large physical size of the filters at lower HF., not to
mention the savings on intermediate stages.

On 13 Apr 2004 10:44:19 -0700, (Tom Bruhns) wrote:

Hi Harold,

Nice of John to make that offer!

As for background and theory, I'll make copies of an artcile or two to
send you, about the discovery of the effect and the optimization of
diode structure to enhance it. I suppose that the effect you're
seeing with the Schottkys is almost entirely capacitive stored charge,
and that won't "sweep out" of the diode with the sharp step you get
with a step-recovery diode. The articles I'll send have info about
efficiency, which can be surprisingly high considering the high order
of multiplication.

What's a sensible target for the multiplication factor using diodes
from say a 4Mhz source? I'd be nice to go straight to say 20X on
account of the large physical size of the filters at lower HF., not to
mention the savings on intermediate stages.

What's a sensible target for the multiplication factor using diodes
from say a 4Mhz source? I'd be nice to go straight to say 20X on
account of the large physical size of the filters at lower HF., not to
mention the savings on intermediate stages.

An 8 MHz filter doesn't have to be physically large Paul, and efficiency
drops pretty fast (Think like a rock) as the multiplication factor goes up.
Have you ever actually defined what it is you're trying to do? Some control
thing in your 70 MHz band? Or real power for some application? Hard to hit a
moving target. Or is that the idea?

W4ZCB

What's a sensible target for the multiplication factor using diodes
from say a 4Mhz source? I'd be nice to go straight to say 20X on
account of the large physical size of the filters at lower HF., not to
mention the savings on intermediate stages.

An 8 MHz filter doesn't have to be physically large Paul, and efficiency
drops pretty fast (Think like a rock) as the multiplication factor goes up.
Have you ever actually defined what it is you're trying to do? Some control
thing in your 70 MHz band? Or real power for some application? Hard to hit a
moving target. Or is that the idea?

W4ZCB

This is a good learning experience for lots of us out here. Any chance of
scanning the printed material and posting , say on a.b.s.e?

On 13 Apr 2004 10:44:19 -0700, (Tom Bruhns) wrote:

Hi Harold,

Nice of John to make that offer!

As for background and theory, I'll make copies of an artcile or two to
send you, about the discovery of the effect and the optimization of
diode structure to enhance it. I suppose that the effect you're
seeing with the Schottkys is almost entirely capacitive stored charge,
and that won't "sweep out" of the diode with the sharp step you get
with a step-recovery diode. The articles I'll send have info about
efficiency, which can be surprisingly high considering the high order
of multiplication.

Cheers,
Tom

"Harold E. Johnson" wrote in message news:3QBec.21137$_K3.55643@attbi_s53...
If you do use diodes for higher-order harmonic generation, and not
just a simple full-wave-rectifier type frequency doubler, I suppose
you want something of the nature of a step recovery diode. That
implies minority carrier stored charge in the diode, and that would
preclude using a Schottky diode (which would work great in the
full-wave-rectifier type doubler). If you get into actually wanting
to generate harmonic combs out to microwave frequencies, it's probably
worthwhile looking for diodes actually characterized for step recovery
service. But I really think that's way beyond what you are trying to
accomplish right now.

My turn to learn something here. Tom, would you elaborate a bit on the above
please? I know SRD's are comb generators out to visible light, but they're
also 50 percent hard to find and 50 percent magic. I've been using
Schottky's for X16 multipliers to 2 GHz, am I doing something wrong? (I keep
promising myself that I'm gonna substitute an MMIC for that one day, I DID
find the "Filter Gain" in the line length from generator to filter), THAT
was both impressive AND helpful. If I go with the MMIC, any preference of
Silicon over GaAs?

Regards

W4ZCB

Tony (remove the "_" to reply by email)

This is a good learning experience for lots of us out here. Any chance of
scanning the printed material and posting , say on a.b.s.e?

On 13 Apr 2004 10:44:19 -0700, (Tom Bruhns) wrote:

Hi Harold,

Nice of John to make that offer!

As for background and theory, I'll make copies of an artcile or two to
send you, about the discovery of the effect and the optimization of
diode structure to enhance it. I suppose that the effect you're
seeing with the Schottkys is almost entirely capacitive stored charge,
and that won't "sweep out" of the diode with the sharp step you get
with a step-recovery diode. The articles I'll send have info about
efficiency, which can be surprisingly high considering the high order
of multiplication.

Cheers,
Tom

"Harold E. Johnson" wrote in message news:3QBec.21137$_K3.55643@attbi_s53...
If you do use diodes for higher-order harmonic generation, and not
just a simple full-wave-rectifier type frequency doubler, I suppose
you want something of the nature of a step recovery diode. That
implies minority carrier stored charge in the diode, and that would
preclude using a Schottky diode (which would work great in the
full-wave-rectifier type doubler). If you get into actually wanting
to generate harmonic combs out to microwave frequencies, it's probably
worthwhile looking for diodes actually characterized for step recovery
service. But I really think that's way beyond what you are trying to
accomplish right now.

My turn to learn something here. Tom, would you elaborate a bit on the above
please? I know SRD's are comb generators out to visible light, but they're
also 50 percent hard to find and 50 percent magic. I've been using
Schottky's for X16 multipliers to 2 GHz, am I doing something wrong? (I keep
promising myself that I'm gonna substitute an MMIC for that one day, I DID
find the "Filter Gain" in the line length from generator to filter), THAT
was both impressive AND helpful. If I go with the MMIC, any preference of
Silicon over GaAs?

Regards

W4ZCB

Tony (remove the "_" to reply by email)

Paul Burridge wrote in message . ..

What's a sensible target for the multiplication factor using diodes
from say a 4Mhz source? I'd be nice to go straight to say 20X on
account of the large physical size of the filters at lower HF., not to
mention the savings on intermediate stages.

Well, somewhat counter to what Harold wrote, the old HP Journal
article I've dredged out to copy says a step recovery diode can do 20X
at 30% efficiency. But that's guys who really understood what they
were doing! (Just coincidentally, the one table they have is for
20X!)

He's right...the filters don't have to be huge. But I'd think of them
as large compared with a SOT-23. The tradeoff is that if you do it
all in one step, you have to have a filter sharp enough to take the
19x and 21x down to your desired level, whatever that is. But with a
5x and a 4x, you can use a couple filters with wider percentage
bandwidths, since for the 5x you'll be using a square-wave input which
has practically no 4th and 6th anyway, and the 3rd and 7th are a big
percentage removed from the 5th...and the 4x can similarly avoid the
3rd and 5th if you do it right.

But again, a PLL can be very small indeed. And I never did see an
answer to the question about does it really need to be locked to your
low freq, or can it be a separate xtal at 70MHz or whatever?

Cheers,
Tom

Paul Burridge wrote in message . ..

What's a sensible target for the multiplication factor using diodes
from say a 4Mhz source? I'd be nice to go straight to say 20X on
account of the large physical size of the filters at lower HF., not to
mention the savings on intermediate stages.

Well, somewhat counter to what Harold wrote, the old HP Journal
article I've dredged out to copy says a step recovery diode can do 20X
at 30% efficiency. But that's guys who really understood what they
were doing! (Just coincidentally, the one table they have is for
20X!)

He's right...the filters don't have to be huge. But I'd think of them
as large compared with a SOT-23. The tradeoff is that if you do it
all in one step, you have to have a filter sharp enough to take the
19x and 21x down to your desired level, whatever that is. But with a
5x and a 4x, you can use a couple filters with wider percentage
bandwidths, since for the 5x you'll be using a square-wave input which
has practically no 4th and 6th anyway, and the 3rd and 7th are a big
percentage removed from the 5th...and the 4x can similarly avoid the
3rd and 5th if you do it right.

But again, a PLL can be very small indeed. And I never did see an
answer to the question about does it really need to be locked to your
low freq, or can it be a separate xtal at 70MHz or whatever?

Cheers,
Tom