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.?

It's an inductor? ;-)

No such thing as a capacitor, or an inductor
or resistor for that matter. They all have
to be modelled as networks with L C and R
don't they?

vy 73

Andy, M1EBV

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

RST Engineering (jw) wrote:

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.



Try them on a toroidal inductor, even at HF. I have good reason to
believe they won't have anything like a model to predict self
capacitance/resonance.

vy 73

Andy, M1EBV

On Mon, 5 Dec 2005 17:14:15 GMT, Andy Cowley
wrote:

RST Engineering (jw) wrote:

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.



Try them on a toroidal inductor, even at HF. I have good reason to
believe they won't have anything like a model to predict self
capacitance/resonance.

vy 73

Andy, M1EBV

Model making is driven by need. 1nF capacitors don't exist on-chip
(at least not very often , so I don't have a model. But I have
built a model of a wirebond that is good up into the 3GHz range.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Andy Cowley wrote:
. . .
IMHO if the results from spice differ from the
real results then spice is wrong.
. . .

If the results from SPICE differ from the real results, then your model
is inadequate.

Roy Lewallen, W7EL

Spice is as good as the input is!
Spice is not a Maxwell field equations solver!

You can predict within 5% without Spice?? How?

- Henry

"Andy Cowley" schrieb im Newsbeitrag
...
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, 5 Dec 2005 23:53:38 +0100, "Henry Kiefer"
wrote:

Spice is as good as the input is!
Spice is not a Maxwell field equations solver!

You can predict within 5% without Spice?? How?

- Henry

[snip]

Some of us have done better than 5% prediction BC (before CAD)... like
for close to 20 years before I ever saw a computer... and 25 years
before simulation software.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Sure Jim. I understand you. That was the time where time was cheaper. Once I
programmed a Gauss linear equations system solver on my Casio FX-602P -
having 512 bytes and even left one byte (for extensions ;-) It was with
minimal input help system (Showing the indices to input) and the matrix was
of dynamical order. (Sorry for my bad english)

I can buy resistors and capacitors with 5%, sometimes with 1%. If you build
a rc oscillator with 1% component values, you get an error typical 1,5%. And
then you add the active components with horrible semiconductor strayung
values. Of course, it is possible with feedback structures to linearize and
stabilize such systems.
So, where is the difference between measurement of the component values and
calculating by hand the circuit OR setting the measured values in the Spice
component dialog boxes? The difference is the time needed and the
possibility to make errors.

5% is a real good value for an analog system.

Hey Jim - Why you don't answer my second private message? :-(

- Henry


"Jim Thompson" schrieb im
Newsbeitrag ...
On Mon, 5 Dec 2005 23:53:38 +0100, "Henry Kiefer"
wrote:

Spice is as good as the input is!
Spice is not a Maxwell field equations solver!

You can predict within 5% without Spice?? How?

- Henry

[snip]

Some of us have done better than 5% prediction BC (before CAD)... like
for close to 20 years before I ever saw a computer... and 25 years
before simulation software.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

The NE85633 bipolar transistor from California Eastern Laboratories
(CEL) ! very cheap quite stable and with a good noise figure. very well
documented by the manufacturer!
try to fish a development kit of SMD coils from Murata, sometimes they
give them away for free.
I personally prefer to go with air wound inductors, they're better and
quite small at these frequencies.
Saandy 4Z5KS

Thanks Saandy! I knew CEL but forget them ;-)

Seems the NE85633 is really cheap and good performance. The package is
reasoable for hobbyists.
Do you already converted the parameters to spice and is it possible to
provide the file to me? Thank you!

Should be a good oscillator and all-purpose amp...


Sure, plain wire is better than the manufactured coils if possible to apply.

cu -
Henry


"Saandy , 4Z5KS" schrieb im Newsbeitrag
oups.com...
The NE85633 bipolar transistor from California Eastern Laboratories
(CEL) ! very cheap quite stable and with a good noise figure. very well
documented by the manufacturer!
try to fish a development kit of SMD coils from Murata, sometimes they
give them away for free.
I personally prefer to go with air wound inductors, they're better and
quite small at these frequencies.
Saandy 4Z5KS