Well, I just typed a search string about SRDs into Google to find the
AN1054 reference. I don't have any magical ideas about finding ALL of
them on the web, but when I moved out library a few months ago, I made
a point of NOT tossing out the ap notes. There's a chance we have it
at work. Now, can I remember to look?

DOn't worry about finding AN983, I have a dog-eared copy here. If YOU want a
copy, I can do the reverse lend-lease thing.

W4ZCB

Well, I just typed a search string about SRDs into Google to find the
AN1054 reference. I don't have any magical ideas about finding ALL of
them on the web, but when I moved out library a few months ago, I made
a point of NOT tossing out the ap notes. There's a chance we have it
at work. Now, can I remember to look?

DOn't worry about finding AN983, I have a dog-eared copy here. If YOU want a
copy, I can do the reverse lend-lease thing.

W4ZCB

On Thu, 15 Apr 2004 20:12:40 +1200, Barry Lennox
wrote:

On Mon, 12 Apr 2004 12:23:09 -0700, John Larkin
wrote:



The only distributor-stock SRDs I know of are the M/Acom MA44767,
MA44768, MA44769 parts, all SOT-23 and dirt cheap. I think Penstock
carries them. The '68 or '69 should be good for multiplication to 2
GHz. For high ratios, an SRD will beat a plain diode by a huge amount.
There are lots of appnotes around about using them as multipliers.

I have a bunch in stock and can send a few to anybody who wants to
play.

MPulse microwave used to be pretty good with samples, I have some
MP4065 SRDs that work well.

Tel # used to be 408 432 1480

Barry lennox

M-Pulse is good guys; we use some of their faster parts, and they are
very helpful. But they apparently don't stock anything, and wire-bond
- even samples - to order. So if you only want a few pieces for
yourself, and don't intend to place a production order, you'll have to
lie to them to get samples.

Metelics is similar; they seem to make the fastest SRD (35 ps) you can
buy on the open market. Not as friendly as M-Pulse, though.

John

On Thu, 15 Apr 2004 20:12:40 +1200, Barry Lennox
wrote:

On Mon, 12 Apr 2004 12:23:09 -0700, John Larkin
wrote:



The only distributor-stock SRDs I know of are the M/Acom MA44767,
MA44768, MA44769 parts, all SOT-23 and dirt cheap. I think Penstock
carries them. The '68 or '69 should be good for multiplication to 2
GHz. For high ratios, an SRD will beat a plain diode by a huge amount.
There are lots of appnotes around about using them as multipliers.

I have a bunch in stock and can send a few to anybody who wants to
play.

MPulse microwave used to be pretty good with samples, I have some
MP4065 SRDs that work well.

Tel # used to be 408 432 1480

Barry lennox

M-Pulse is good guys; we use some of their faster parts, and they are
very helpful. But they apparently don't stock anything, and wire-bond
- even samples - to order. So if you only want a few pieces for
yourself, and don't intend to place a production order, you'll have to
lie to them to get samples.

Metelics is similar; they seem to make the fastest SRD (35 ps) you can
buy on the open market. Not as friendly as M-Pulse, though.

John

Paul Burridge wrote:

On Wed, 14 Apr 2004 00:36:17 GMT, "Harold E. Johnson"
wrote:

An 8 MHz filter doesn't have to be physically large Paul,

Hi Q coils in that frequency range in compact sizes... they don't seem
to go together. :-(

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?

Yeah, moving target's good. Keep the discussion generalised and it
might help others as well. I'm not sure where the 70Mhz figure comes
from, but it's a good enough guess by whoever made it. However, the
final desired frequency in my particular case is in the region of
40Mhz which will be achieved by mixing down with the output from
another oscillator and filtering.

A high Q resonant circuit can be rather small.
For example, i made a tunable LC with a Q approaching 1000, and it was
not the size of a garbage can (resonant cavity); it was about 5 inches
tall and about 3 inches in diameter.
On one extreme, one uses standard LC parts and get fair Qs in small
size.
On the other extreme, one makes a ersonant cavity to get very high Qs
at the expense of size.
In between there is something that can be called either a "shielded
inductor" or a "resonant cavity with slow wave structure".
One takes an inductor and places it in the center of a metal cylinder;
one end of the inductor attaches to the inner wall (makes electrical
connection and acts as support).
The capacitance to the walls (and added ends) is the other half. Move
an end for fine tuning.
Rather ingenious; ther was an IEE paper 20 years(??) ago covering the
desigh equations.
The terminology used was "Helical resonator".

Paul Burridge wrote:

On Wed, 14 Apr 2004 00:36:17 GMT, "Harold E. Johnson"
wrote:

An 8 MHz filter doesn't have to be physically large Paul,

Hi Q coils in that frequency range in compact sizes... they don't seem
to go together. :-(

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?

Yeah, moving target's good. Keep the discussion generalised and it
might help others as well. I'm not sure where the 70Mhz figure comes
from, but it's a good enough guess by whoever made it. However, the
final desired frequency in my particular case is in the region of
40Mhz which will be achieved by mixing down with the output from
another oscillator and filtering.

A high Q resonant circuit can be rather small.
For example, i made a tunable LC with a Q approaching 1000, and it was
not the size of a garbage can (resonant cavity); it was about 5 inches
tall and about 3 inches in diameter.
On one extreme, one uses standard LC parts and get fair Qs in small
size.
On the other extreme, one makes a ersonant cavity to get very high Qs
at the expense of size.
In between there is something that can be called either a "shielded
inductor" or a "resonant cavity with slow wave structure".
One takes an inductor and places it in the center of a metal cylinder;
one end of the inductor attaches to the inner wall (makes electrical
connection and acts as support).
The capacitance to the walls (and added ends) is the other half. Move
an end for fine tuning.
Rather ingenious; ther was an IEE paper 20 years(??) ago covering the
desigh equations.
The terminology used was "Helical resonator".

It may be of interest -

Doubling the length and diameter of a solenoid and reducing the number of
turns of thicker wire to maintain the same inductance, doubles the Q until
radiation loss resistance begins to predominate.

And it's a big coil for radiation resistance to predominate.
----
Reg, G4FGQ

It may be of interest -

Doubling the length and diameter of a solenoid and reducing the number of
turns of thicker wire to maintain the same inductance, doubles the Q until
radiation loss resistance begins to predominate.

And it's a big coil for radiation resistance to predominate.
----
Reg, G4FGQ

On Fri, 16 Apr 2004 08:19:10 GMT, Robert Baer
wrote:

Paul Burridge wrote:

On Wed, 14 Apr 2004 00:36:17 GMT, "Harold E. Johnson"
wrote:

An 8 MHz filter doesn't have to be physically large Paul,

Hi Q coils in that frequency range in compact sizes... they don't seem
to go together. :-(

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?

Yeah, moving target's good. Keep the discussion generalised and it
might help others as well. I'm not sure where the 70Mhz figure comes
from, but it's a good enough guess by whoever made it. However, the
final desired frequency in my particular case is in the region of
40Mhz which will be achieved by mixing down with the output from
another oscillator and filtering.

A high Q resonant circuit can be rather small.
For example, i made a tunable LC with a Q approaching 1000, and it was
not the size of a garbage can (resonant cavity); it was about 5 inches
tall and about 3 inches in diameter.
On one extreme, one uses standard LC parts and get fair Qs in small
size.
On the other extreme, one makes a ersonant cavity to get very high Qs
at the expense of size.
In between there is something that can be called either a "shielded
inductor" or a "resonant cavity with slow wave structure".
One takes an inductor and places it in the center of a metal cylinder;
one end of the inductor attaches to the inner wall (makes electrical
connection and acts as support).
The capacitance to the walls (and added ends) is the other half. Move
an end for fine tuning.
Rather ingenious; ther was an IEE paper 20 years(??) ago covering the
desigh equations.
The terminology used was "Helical resonator".

Coaxial ceramic resonators are cool... they are small, extremely
stable, and have Qs in the thousands.

John

On Fri, 16 Apr 2004 08:19:10 GMT, Robert Baer
wrote:

Paul Burridge wrote:

On Wed, 14 Apr 2004 00:36:17 GMT, "Harold E. Johnson"
wrote:

An 8 MHz filter doesn't have to be physically large Paul,

Hi Q coils in that frequency range in compact sizes... they don't seem
to go together. :-(

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?

Yeah, moving target's good. Keep the discussion generalised and it
might help others as well. I'm not sure where the 70Mhz figure comes
from, but it's a good enough guess by whoever made it. However, the
final desired frequency in my particular case is in the region of
40Mhz which will be achieved by mixing down with the output from
another oscillator and filtering.

A high Q resonant circuit can be rather small.
For example, i made a tunable LC with a Q approaching 1000, and it was
not the size of a garbage can (resonant cavity); it was about 5 inches
tall and about 3 inches in diameter.
On one extreme, one uses standard LC parts and get fair Qs in small
size.
On the other extreme, one makes a ersonant cavity to get very high Qs
at the expense of size.
In between there is something that can be called either a "shielded
inductor" or a "resonant cavity with slow wave structure".
One takes an inductor and places it in the center of a metal cylinder;
one end of the inductor attaches to the inner wall (makes electrical
connection and acts as support).
The capacitance to the walls (and added ends) is the other half. Move
an end for fine tuning.
Rather ingenious; ther was an IEE paper 20 years(??) ago covering the
desigh equations.
The terminology used was "Helical resonator".

Coaxial ceramic resonators are cool... they are small, extremely
stable, and have Qs in the thousands.

John