Hi all -

I'm not new to electronics but to vhf comm. I want to build small circuits:
LNA, power amp to 10 watts, etc. At the moment between 10MegHz and 150MegHz.

What are the standard parts, cheap but effective, preferable with spice
model availability (I'm doing much with LTspice)?
Transistors, ICs, coil-suppliers, suppliers in general for small quantities

Please no triodes etc. I like more SMD ;-)
Lists somewhere in the net? Japanese parts?

I think such lists will be of interest to others too!

Thank you!!

Best regards -
Henry

You are going to use Spice to model an RF circuit. DId I get that right?

Jim



"Henry Kiefer" wrote in message
...
Hi all -

I'm not new to electronics but to vhf comm. I want to build small
circuits:
LNA, power amp to 10 watts, etc. At the moment between 10MegHz and
150MegHz.

What are the standard parts, cheap but effective, preferable with spice
model availability (I'm doing much with LTspice)?
Transistors, ICs, coil-suppliers, suppliers in general for small
quantities

Yes Jim!
Im not very experienced there (Digital designs/layout is my profession) -
but for example I designed a LNA and got simulations results (even for noise
performance) very similar to a real circuit built from a ham with great
background (found later on the net).
Even a Synchronous Oscillator for 145MegHz seem to work with LTspice. I work
on it today trying to modify it to an fsk modulated power oscillator to keep
component count to the lowest.

Why you ask?

- Henry


"RST Engineering (jw)" schrieb im Newsbeitrag
...
You are going to use Spice to model an RF circuit. DId I get that right?

Jim



"Henry Kiefer" wrote in message
...
Hi all -

I'm not new to electronics but to vhf comm. I want to build small
circuits:
LNA, power amp to 10 watts, etc. At the moment between 10MegHz and
150MegHz.

What are the standard parts, cheap but effective, preferable with spice
model availability (I'm doing much with LTspice)?
Transistors, ICs, coil-suppliers, suppliers in general for small
quantities

On Mon, 21 Nov 2005 16:40:40 -0800, "RST Engineering \(jw\)"
wrote:

You are going to use Spice to model an RF circuit. DId I get that right?

Jim



Why not?

John

Well, just for starters, what does Spice say about a 1000 pf capacitor with
either ½" lead lengths or a total of 1" of PCB trace at 150 MHz.?

Jim




"John Larkin" wrote in message
...
On Mon, 21 Nov 2005 16:40:40 -0800, "RST Engineering \(jw\)"
wrote:

You are going to use Spice to model an RF circuit. DId I get that right?

Jim



Why not?

John

Ok Jim. You're asked about the stray components hidden in the real
parts/circuit. If you take the values from the datasheets for die and/or
package or give it a guess if not available, and add values for the pcb
lines, you have a good simulation result. The pcb by itself is not of much
interest if you simulate not much over 100MegHz. Even starting a oscillator
with thermal noise is possible!
Sure, you must know what you're doing :-)

Spice by itself can simulate almost all if you have the right models
included - even if you wanna simulate a mechanical system. There is no
frequency limit at least to 100GHz.

Do you had bad result doing Spice?

To come back to your question: Spice will give you better results than your
real circuit! You can connect a probe with no interaction to the circuit!
Try this with your real parts! Don't forget the component variations in real
circuits coming from the manufacturing processes of the parts.

- Henry



"RST Engineering" schrieb im Newsbeitrag
...
Well, just for starters, what does Spice say about a 1000 pf capacitor
with
either ½" lead lengths or a total of 1" of PCB trace at 150 MHz.?

Jim




"John Larkin" wrote in
message
...
On Mon, 21 Nov 2005 16:40:40 -0800, "RST Engineering \(jw\)"
wrote:

You are going to use Spice to model an RF circuit. DId I get that
right?

Jim



Why not?

John

"Henry Kiefer" wrote in message
...

Ok Jim. You're asked about the stray components hidden in the real
parts/circuit.

There is nothing hidden at all. Strays are a part of the real life at VHF
and above. Sometimes strays have more effect than the part itself.



If you take the values from the datasheets for die and/or
package or give it a guess if not available, and add values for the pcb
lines, you have a good simulation result.

Horsefeathers. What "values" do you add for the pcb lines?



The pcb by itself is not of much
interest if you simulate not much over 100MegHz. Even starting a
oscillator
with thermal noise is possible!
Sure, you must know what you're doing :-)

As with anything in the world.



Spice by itself can simulate almost all if you have the right models
included - even if you wanna simulate a mechanical system. There is no
frequency limit at least to 100GHz.

The problem is getting the right models, which is an art in and of itself.




Do you had bad result doing Spice?

To come back to your question: Spice will give you better results than
your
real circuit! You can connect a probe with no interaction to the circuit!
Try this with your real parts! Don't forget the component variations in
real
circuits coming from the manufacturing processes of the parts.

Again I ask the question: What does Spice say about a 1000 pf capacitor
with 1" total lead length at 150 MHz.? Don't give me the BS about Spice
being "better than a real circuit". Until you can give me a ferrite slug on
one end of a toothpick and a brass slug on the other end to increase or
decrease inductance in Spice, the physical circuit is the "real" circuit.

Jim

Henry Kiefer wrote:


To come back to your question: Spice will give you better results than your
real circuit!

Worked much DX with Spice, have you?

IMHO if the results from spice differ from the
real results then spice is wrong.

BTW have you got a realistic model for the
self-capacitance of an inductor? Can you
predict the self resonance within 5%?


vy 73

Andy, M1EBV

On Mon, 21 Nov 2005 23:55:26 -0800, "RST Engineering"
wrote:

Well, just for starters, what does Spice say about a 1000 pf capacitor with
either ½" lead lengths or a total of 1" of PCB trace at 150 MHz.?

Jim



When they matter, just poke in the appropriate series L or a bit of
transmission line. I use Spice now and then to sim picosecond stuff.
Even if the simulation isn't highly accurate, it helps train your
instincts, shows you which parasitics will have which effects, so when
you build the real thing you have a jump on the complexity.

Hell, 150 MHz is slow.

John

Agreed, John, 150 MHz is damned near DC for a lot of us, but as yet I have
no answer from the "spice" folks for the 1 nf capacitor question. A lot of
fancydancing but no answers.

Jim



"John Larkin" wrote in message
...
On Mon, 21 Nov 2005 23:55:26 -0800, "RST Engineering"
wrote:

Well, just for starters, what does Spice say about a 1000 pf capacitor
with
either ½" lead lengths or a total of 1" of PCB trace at 150 MHz.?

Jim



When they matter, just poke in the appropriate series L or a bit of
transmission line. I use Spice now and then to sim picosecond stuff.
Even if the simulation isn't highly accurate, it helps train your
instincts, shows you which parasitics will have which effects, so when
you build the real thing you have a jump on the complexity.

Hell, 150 MHz is slow.

John