Driver to drive?

[Joerg]

Joerg wrote:

Clifford Heath wrote:
On 22/11/14 03:04, Joerg wrote:
rickman wrote:
On 11/21/2014 6:21 AM, Clifford Heath wrote:
On 21/11/14 19:15, rickman wrote:
On 11/21/2014 4:10 AM, josephkk wrote:
On Fri, 21 Nov 2014 10:51:57 +1100, Clifford Heath
no.spam@please.net
wrote:

On 19/11/14 09:02, rickman wrote:
Thanks for helping me understand this.

Now I need to figure out why the Cascode design doesn't deliver a
higher
gain. It should, right? Ah, I just found it. He left the
output on
the drain to emitter leg and the output is now on the collector!
That's
much better giving some 75 dB at 60 kHz now.

Thanks, I think I learned a few things. Now if I can bias the
circuit
properly.
I've previously mentioned my 350MHz RF probe/amplifier, which uses a
cascode. If you want to explore it in LTSpice, the full design files
and
performance measurements are here:

http://cjh.polyplex.org/electronics/RFCascodeProbe/

The bandwidth is limited by the Ciss of the FET and the probe lead
inductance.

Something I don't understand, which someone more experienced
might be
able to explain, is why I had to add such a large source
resistance to
the input to kill the resonance between the input inductance and the
Ciss. Input inductance is approximately right for a pair of 4mm
probes,
and they won't have appreciable resistance. What kills this
resonance in
real life?

Clifford Heath.
I am not sure what difference it will make but i would try capacitors
from
the drain to ground to remove any AC gain to the drain which will
have
some interesting side effects.
Yes, that sounds right. If you are using a source follower why have a
resistor in the drain leg? The only time I have seen balanced
resistors
in the source and drain legs without bypass caps is when generating
differential signals. I would say in this case the drain resistor is
simply inappropriate and is setting up the input for the Miller
effect.
Either bypass or remove R11.
R11 was only there in the schematic file - you'll see it's a piece of
wire in the photos. It's not in the LTSpice file. So the drain is
directly bypassed to ground.

10pF Ciss and 20nH (for 20mm total) is about right for the measured
350MHz. That much is explained. But if you look at the LTSpice and
remove the extra capacitance C6, you get a massive resonant peak which
isn't there in the physical measurements. I played with source
resistance as a mechanism, but I still can't get the Spice to act like
the measured curves.
I don't know that much about the models or the actual circuits really.
Maybe Joerg could give an opinion or some of the others here who know
about such things?

Source or emitter followers can be like a sports cars on a sheet of ice,
even oscillate. Hard to see the layout but a few hints. Please don't
take that as an attempt to pick on the design, just suggestions:

1. R10 sould be via'd straight to GND at its pad and not looped all the
way to the input GND terminal.

2. R11: Just jumpering it does not really take it out in the RF world.
The drain would have to be via'd straight to 9V nd that 9V should be a
plane.

3. C7 does a "loop-de-loop" and that adds unwanted inductance.

4. Parts on RF probes should be 0402 or 0603 at the most. Otherwise
there is too much inductance. For bypass caps consider side-contact ones.

5. Grund plane: It is almost broken in the neck area. Needs to be
flooded.

6. Use a 4-layer board. 2-layer is very tough because you can't have a
supply plane.
Sincere thanks for your gems, Joerg. This is my first design above HF,
which you can probably see!


Don't sell yourself short, you got it to work and do what you wanted it
to do. That's what matters.

We all start into new turf at some point, usually all the time. When I
applied for my first job (medical ultrasound) I wondered what they do
with depth sounders on humans. Luckily they didn't ask me anything
medical, it would have been a major embarrassment.


I'm not unhappy with the measured performance (it's quite well-behaved
up to and around 350MHz) even though it could easily be improved as you
point out. The behaviour that still puzzles me is what LTSpice predicts
however.

Why does Spice predict such a hump (without C6), and what needs to be
added to the simulation to make it match reality? Maybe JimT has some
thoughts, or one of the other LTSpice gurus?


It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.

Note to readers of this thread: The designators refer to the posted
LTSpice simulator file, not the displayed schematic.

http://cjh.polyplex.org/electronics/RFCascodeProbe/RFProbeCascodeAmp.asc

To make it run you also have to load the BF862 and BFR93A models into
Notepad each and then store in the same directory where the simulator
file is as BF862.mod and BFR93A.sub.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Martin Riddle]

On Fri, 21 Nov 2014 23:46:38 -0800, miso <miso@sushi.com> wrote:

Robert Baer wrote:

Like the GC Electronics 19-1902 fer eggzampull?
Need only one bottle, not a case.
If i remember correctly, this DE-OX-ID was reddish in color and was
the super-daddy to their 10-630 JIF-ACTION (slightly yellow).
One bottle will last "forever".

I use Caig Deoxit. Not cheap, but whatever.

19-1902 on Newark $15
19-1902 on ebay $15
Deoxit (spray) on partsexpress $20
Deoxit (spray) on newark $20

I've used Deoxit and it works well.
One can is more than enough.

Cheers

 

[DecadentLinuxUserNumeroUn]

On Sat, 22 Nov 2014 13:45:57 -0500, Martin Riddle
<martin_rid@verizon.net> Gave us:

On Fri, 21 Nov 2014 23:46:38 -0800, miso <miso@sushi.com> wrote:

Robert Baer wrote:

Like the GC Electronics 19-1902 fer eggzampull?
Need only one bottle, not a case.
If i remember correctly, this DE-OX-ID was reddish in color and was
the super-daddy to their 10-630 JIF-ACTION (slightly yellow).
One bottle will last "forever".

I use Caig Deoxit. Not cheap, but whatever.

19-1902 on Newark $15
19-1902 on ebay $15
Deoxit (spray) on partsexpress $20
Deoxit (spray) on newark $20

I've used Deoxit and it works well.
One can is more than enough.

Cheers

www.amazon.com/Clear-Care-Hydrogen-peroxide-Cleaning/dp/B0076P12W2

Heheheheh!

 

[josephkk]

On Sat, 22 Nov 2014 07:59:41 -0800, Joerg <news@analogconsultants.com>
wrote:

It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.


Note to readers of this thread: The designators refer to the posted
LTSpice simulator file, not the displayed schematic.

http://cjh.polyplex.org/electronics/RFCascodeProbe/RFProbeCascodeAmp.asc

To make it run you also have to load the BF862 and BFR93A models into
Notepad each and then store in the same directory where the simulator
file is as BF862.mod and BFR93A.sub.

I can get the circuit to display just fine but even with the files i
cannot seem to get the circuit to "compile" properly. I am doing
something wrong with the fet model. I have all 4 files in a working
directory. Maybe i missed something in file names. The schematic comes
up cleanly.

Here is the log file:
--------------------------
Circuit: * C:\windows\profiles\joseph2k\My
Documents\Downloads\LTSpice\RFProbeCascodeAmp.asc

Error on line 3 : j1 vcc n002 vs jbf862 njf
Unknown parameter "njf"
Direct Newton iteration for .op point succeeded.
..step c6=7e-012
..step c6=1.2e-011
..step c6=1.7e-011
..step c6=2.2e-011
..step c6=2.7e-011
..step c6=3.2e-011

Date: Sat Nov 22 21:19:57 2014
Total elapsed time: 0.188 seconds.

tnom = 27
temp = 27
method = trap
totiter = 7
traniter = 0
tranpoints = 0
accept = 0
rejected = 0
matrix size = 41
fillins = 48
solver = Normal
Matrix Compiler1: 335 opcodes
Matrix Compiler2: 4.37 KB object code size


--------------------------

???=/

 

Martin Riddle <martin_rid@verizon.net> wrote:

Robert Baer wrote:

Like the GC Electronics 19-1902 fer eggzampull?
Need only one bottle, not a case.

19-1902 on Newark $15
19-1902 on ebay $15

19-1902 over the counter at the local electronics distributor, $7.60 +
tax (which is roughly 9%), for roughly $8.30 total.

For stuff like this, you often end up fighting the hazmat charges from
the shippers. Sometimes they charge the same for one can as for as a
case, so it's a little cheaper to let the store order the case and
split up the charge over 12 or 24 cans.

Matt Roberds

 

[rickman]

On 11/23/2014 12:37 AM, josephkk wrote:

On Sat, 22 Nov 2014 07:59:41 -0800, Joerg <news@analogconsultants.com
wrote:


It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.


Note to readers of this thread: The designators refer to the posted
LTSpice simulator file, not the displayed schematic.

http://cjh.polyplex.org/electronics/RFCascodeProbe/RFProbeCascodeAmp.asc

To make it run you also have to load the BF862 and BFR93A models into
Notepad each and then store in the same directory where the simulator
file is as BF862.mod and BFR93A.sub.

I can get the circuit to display just fine but even with the files i
cannot seem to get the circuit to "compile" properly. I am doing
something wrong with the fet model. I have all 4 files in a working
directory. Maybe i missed something in file names. The schematic comes
up cleanly.

Here is the log file:
--------------------------
Circuit: * C:\windows\profiles\joseph2k\My
Documents\Downloads\LTSpice\RFProbeCascodeAmp.asc

Error on line 3 : j1 vcc n002 vs jbf862 njf
Unknown parameter "njf"
Direct Newton iteration for .op point succeeded.
..step c6=7e-012
..step c6=1.2e-011
..step c6=1.7e-011
..step c6=2.2e-011
..step c6=2.7e-011
..step c6=3.2e-011

Date: Sat Nov 22 21:19:57 2014
Total elapsed time: 0.188 seconds.

tnom = 27
temp = 27
method = trap
totiter = 7
traniter = 0
tranpoints = 0
accept = 0
rejected = 0
matrix size = 41
fillins = 48
solver = Normal
Matrix Compiler1: 335 opcodes
Matrix Compiler2: 4.37 KB object code size

Where did you get your model file? I'm not sure what line the error is
complaining about, but I think it is the model file. Here are the lines
from the .asc file for the symbols of the JFET I used.

SYMBOL njf 320 32 R0
SYMATTR InstName T1
SYMATTR Value JBF862

I think njf is just a reference to the symbol and the link to the model
is the last line referencing JBF862 which is in the model file as shown
below. The model file is included using the following spice directive,
but there are many ways of doing this including adding it directly to
the schematic.

TEXT -24 400 Left 2 !.lib Simulations\\spice_BF862.prm

Here is the model file, spice_BF862.prm which I got from the NXP web site.

* BF862 SPICE MODEL MARCH 2007 NXP SEMICONDUCTORS
* ENVELOPE SOT23
* JBF862: 1, Drain, 2,Gate, 3,Source
Ld 1 4 L= 1.1nH
Ls 3 6 L= 1.25nH
Lg 2 5 L= 0.78nH
Rg 5 7 R= 0.535 Ohm
Cds 1 3 C= 0.0001pF
Cgs 2 3 C= 1.05pF
Cgd 1 2 C= 0.201pF
Co 4 6 C= 0.35092pF
JBF862 model parameters:
..model JBF862 NJF(Beta=47.800E-3 Betatce=-.5 Rd=.8 Rs=7.5000
Lambda=37.300E-3 Vto=-.57093
+ Vtotc=-2.0000E-3 Is=424.60E-12 Isr=2.995p N=1 Nr=2 Xti=3 Alpha=-1.0000E-3
+ Vk=59.97 Cgd=7.4002E-12 M=.6015 Pb=.5 Fc=.5 Cgs=8.2890E-12 Kf=87.5E-18
+ Af=1)
ENDS BF862

NJF

--

Rick

 

[Robert Baer]

Martin Riddle wrote:

On Fri, 21 Nov 2014 23:46:38 -0800, miso<miso@sushi.com> wrote:

Robert Baer wrote:

Like the GC Electronics 19-1902 fer eggzampull?
Need only one bottle, not a case.
If i remember correctly, this DE-OX-ID was reddish in color and was
the super-daddy to their 10-630 JIF-ACTION (slightly yellow).
One bottle will last "forever".

I use Caig Deoxit. Not cheap, but whatever.

19-1902 on Newark $15
19-1902 on ebay $15
Deoxit (spray) on partsexpress $20
Deoxit (spray) on newark $20

I've used Deoxit and it works well.
One can is more than enough.

Cheers
Like i implied; HEXpen$$ive.

 

[Robert Baer]

DecadentLinuxUserNumeroUno wrote:

On Sat, 22 Nov 2014 13:45:57 -0500, Martin Riddle
martin_rid@verizon.net> Gave us:

On Fri, 21 Nov 2014 23:46:38 -0800, miso<miso@sushi.com> wrote:

Robert Baer wrote:

Like the GC Electronics 19-1902 fer eggzampull?
Need only one bottle, not a case.
If i remember correctly, this DE-OX-ID was reddish in color and was
the super-daddy to their 10-630 JIF-ACTION (slightly yellow).
One bottle will last "forever".

I use Caig Deoxit. Not cheap, but whatever.

19-1902 on Newark $15
19-1902 on ebay $15
Deoxit (spray) on partsexpress $20
Deoxit (spray) on newark $20

I've used Deoxit and it works well.
One can is more than enough.

Cheers


www.amazon.com/Clear-Care-Hydrogen-peroxide-Cleaning/dp/B0076P12W2

Heheheheh!

Burnt water. Decomposes easily; make sure water was burnt within a
week of obtaining and use.
HEXspen$$ive there.

 

[Clifford Heath]

On 22/11/14 13:33, Joerg wrote:

Clifford Heath wrote:
On 22/11/14 03:04, Joerg wrote:
rickman wrote:
On 11/21/2014 6:21 AM, Clifford Heath wrote:
On 21/11/14 19:15, rickman wrote:
On 11/21/2014 4:10 AM, josephkk wrote:
On Fri, 21 Nov 2014 10:51:57 +1100, Clifford Heath
no.spam@please.net
wrote:

On 19/11/14 09:02, rickman wrote:
Thanks for helping me understand this.

Now I need to figure out why the Cascode design doesn't deliver a
higher
gain. It should, right? Ah, I just found it. He left the
output on
the drain to emitter leg and the output is now on the collector!
That's
much better giving some 75 dB at 60 kHz now.

Thanks, I think I learned a few things. Now if I can bias the
circuit
properly.

I've previously mentioned my 350MHz RF probe/amplifier, which uses a
cascode. If you want to explore it in LTSpice, the full design files
and
performance measurements are here:

http://cjh.polyplex.org/electronics/RFCascodeProbe/

The bandwidth is limited by the Ciss of the FET and the probe lead
inductance.

Something I don't understand, which someone more experienced
might be
able to explain, is why I had to add such a large source
resistance to
the input to kill the resonance between the input inductance and the
Ciss. Input inductance is approximately right for a pair of 4mm
probes,
and they won't have appreciable resistance. What kills this
resonance in
real life?

Clifford Heath.

I am not sure what difference it will make but i would try capacitors
from
the drain to ground to remove any AC gain to the drain which will
have
some interesting side effects.

Yes, that sounds right. If you are using a source follower why have a
resistor in the drain leg? The only time I have seen balanced
resistors
in the source and drain legs without bypass caps is when generating
differential signals. I would say in this case the drain resistor is
simply inappropriate and is setting up the input for the Miller
effect.
Either bypass or remove R11.

R11 was only there in the schematic file - you'll see it's a piece of
wire in the photos. It's not in the LTSpice file. So the drain is
directly bypassed to ground.

10pF Ciss and 20nH (for 20mm total) is about right for the measured
350MHz. That much is explained. But if you look at the LTSpice and
remove the extra capacitance C6, you get a massive resonant peak which
isn't there in the physical measurements. I played with source
resistance as a mechanism, but I still can't get the Spice to act like
the measured curves.

I don't know that much about the models or the actual circuits really.
Maybe Joerg could give an opinion or some of the others here who know
about such things?


Source or emitter followers can be like a sports cars on a sheet of ice,
even oscillate. Hard to see the layout but a few hints. Please don't
take that as an attempt to pick on the design, just suggestions:

1. R10 sould be via'd straight to GND at its pad and not looped all the
way to the input GND terminal.

2. R11: Just jumpering it does not really take it out in the RF world.
The drain would have to be via'd straight to 9V nd that 9V should be a
plane.

3. C7 does a "loop-de-loop" and that adds unwanted inductance.

4. Parts on RF probes should be 0402 or 0603 at the most. Otherwise
there is too much inductance. For bypass caps consider side-contact ones.

5. Grund plane: It is almost broken in the neck area. Needs to be
flooded.

6. Use a 4-layer board. 2-layer is very tough because you can't have a
supply plane.

Sincere thanks for your gems, Joerg. This is my first design above HF,
which you can probably see!


Don't sell yourself short, you got it to work and do what you wanted it
to do. That's what matters.

We all start into new turf at some point, usually all the time. When I
applied for my first job (medical ultrasound) I wondered what they do
with depth sounders on humans. Luckily they didn't ask me anything
medical, it would have been a major embarrassment.


I'm not unhappy with the measured performance (it's quite well-behaved
up to and around 350MHz) even though it could easily be improved as you
point out. The behaviour that still puzzles me is what LTSpice predicts
however.

Why does Spice predict such a hump (without C6), and what needs to be
added to the simulation to make it match reality? Maybe JimT has some
thoughts, or one of the other LTSpice gurus?


It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.

Of course - that's how I designed it originally. But the sim then said
it would be flat to 800+MHz. After I built it we measured that it only
works to 350. I added the probe inductance (10nH/cm) in an attempt to
model what was actually happening. It stopped at 350MHz right enough,
but with a massive hump that wasn't in the measured data.

Does that just mean that modelling the probe as a pure inductance
instead of an RLC network is inadequate?

Clifford Heath.

 

[Joerg]

josephkk wrote:

On Sat, 22 Nov 2014 07:59:41 -0800, Joerg <news@analogconsultants.com
wrote:

It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.

Note to readers of this thread: The designators refer to the posted
LTSpice simulator file, not the displayed schematic.

http://cjh.polyplex.org/electronics/RFCascodeProbe/RFProbeCascodeAmp.asc

To make it run you also have to load the BF862 and BFR93A models into
Notepad each and then store in the same directory where the simulator
file is as BF862.mod and BFR93A.sub.

I can get the circuit to display just fine but even with the files i
cannot seem to get the circuit to "compile" properly. I am doing
something wrong with the fet model. I have all 4 files in a working
directory. Maybe i missed something in file names. The schematic comes
up cleanly.

Here is the log file:
--------------------------
Circuit: * C:\windows\profiles\joseph2k\My
Documents\Downloads\LTSpice\RFProbeCascodeAmp.asc

Error on line 3 : j1 vcc n002 vs jbf862 njf
Unknown parameter "njf"
Direct Newton iteration for .op point succeeded.
.step c6=7e-012
.step c6=1.2e-011
.step c6=1.7e-011
.step c6=2.2e-011
.step c6=2.7e-011
.step c6=3.2e-011

Date: Sat Nov 22 21:19:57 2014
Total elapsed time: 0.188 seconds.

tnom = 27
temp = 27
method = trap
totiter = 7
traniter = 0
tranpoints = 0
accept = 0
rejected = 0
matrix size = 41
fillins = 48
solver = Normal
Matrix Compiler1: 335 opcodes
Matrix Compiler2: 4.37 KB object code size


--------------------------

???=/

As Rick said, it reads in the wrong model. You have to put Clifford's
simulator file into a new directory and then add the two files outlined
above into it, with those exact prefixes and suffixes. Nothing else
should be in that directory. Then start the sim from there.

This is why my server now has a "Heath" directory

One thing that really helps other verify or duplicate sims is to put all
the model information in the simulator file instead of file calls.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

Clifford Heath wrote:

On 22/11/14 13:33, Joerg wrote:
Clifford Heath wrote:
On 22/11/14 03:04, Joerg wrote:
rickman wrote:
On 11/21/2014 6:21 AM, Clifford Heath wrote:
On 21/11/14 19:15, rickman wrote:
On 11/21/2014 4:10 AM, josephkk wrote:
On Fri, 21 Nov 2014 10:51:57 +1100, Clifford Heath
no.spam@please.net
wrote:

On 19/11/14 09:02, rickman wrote:
Thanks for helping me understand this.

Now I need to figure out why the Cascode design doesn't deliver a
higher
gain. It should, right? Ah, I just found it. He left the
output on
the drain to emitter leg and the output is now on the collector!
That's
much better giving some 75 dB at 60 kHz now.

Thanks, I think I learned a few things. Now if I can bias the
circuit
properly.

I've previously mentioned my 350MHz RF probe/amplifier, which
uses a
cascode. If you want to explore it in LTSpice, the full design
files
and
performance measurements are here:

http://cjh.polyplex.org/electronics/RFCascodeProbe/

The bandwidth is limited by the Ciss of the FET and the probe lead
inductance.

Something I don't understand, which someone more experienced
might be
able to explain, is why I had to add such a large source
resistance to
the input to kill the resonance between the input inductance
and the
Ciss. Input inductance is approximately right for a pair of 4mm
probes,
and they won't have appreciable resistance. What kills this
resonance in
real life?

Clifford Heath.

I am not sure what difference it will make but i would try
capacitors
from
the drain to ground to remove any AC gain to the drain which will
have
some interesting side effects.

Yes, that sounds right. If you are using a source follower why
have a
resistor in the drain leg? The only time I have seen balanced
resistors
in the source and drain legs without bypass caps is when generating
differential signals. I would say in this case the drain
resistor is
simply inappropriate and is setting up the input for the Miller
effect.
Either bypass or remove R11.

R11 was only there in the schematic file - you'll see it's a piece of
wire in the photos. It's not in the LTSpice file. So the drain is
directly bypassed to ground.

10pF Ciss and 20nH (for 20mm total) is about right for the measured
350MHz. That much is explained. But if you look at the LTSpice and
remove the extra capacitance C6, you get a massive resonant peak
which
isn't there in the physical measurements. I played with source
resistance as a mechanism, but I still can't get the Spice to act
like
the measured curves.

I don't know that much about the models or the actual circuits really.
Maybe Joerg could give an opinion or some of the others here who know
about such things?


Source or emitter followers can be like a sports cars on a sheet of
ice,
even oscillate. Hard to see the layout but a few hints. Please don't
take that as an attempt to pick on the design, just suggestions:

1. R10 sould be via'd straight to GND at its pad and not looped all the
way to the input GND terminal.

2. R11: Just jumpering it does not really take it out in the RF world.
The drain would have to be via'd straight to 9V nd that 9V should be a
plane.

3. C7 does a "loop-de-loop" and that adds unwanted inductance.

4. Parts on RF probes should be 0402 or 0603 at the most. Otherwise
there is too much inductance. For bypass caps consider side-contact
ones.

5. Grund plane: It is almost broken in the neck area. Needs to be
flooded.

6. Use a 4-layer board. 2-layer is very tough because you can't have a
supply plane.

Sincere thanks for your gems, Joerg. This is my first design above HF,
which you can probably see!


Don't sell yourself short, you got it to work and do what you wanted it
to do. That's what matters.

We all start into new turf at some point, usually all the time. When I
applied for my first job (medical ultrasound) I wondered what they do
with depth sounders on humans. Luckily they didn't ask me anything
medical, it would have been a major embarrassment.


I'm not unhappy with the measured performance (it's quite well-behaved
up to and around 350MHz) even though it could easily be improved as you
point out. The behaviour that still puzzles me is what LTSpice predicts
however.

Why does Spice predict such a hump (without C6), and what needs to be
added to the simulation to make it match reality? Maybe JimT has some
thoughts, or one of the other LTSpice gurus?


It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.

Of course - that's how I designed it originally. But the sim then said
it would be flat to 800+MHz. After I built it we measured that it only
works to 350. I added the probe inductance (10nH/cm) in an attempt to
model what was actually happening. It stopped at 350MHz right enough,
but with a massive hump that wasn't in the measured data.

If it wasn't in the measured data then the probe inductance isn't as bad
as assumed.

Does that just mean that modelling the probe as a pure inductance
instead of an RLC network is inadequate?

It's the probe plus input capacitances that form a lowpass filter. But
it doesn't have Bessel characteristics so you get a peak. Just like you
would if you designed a real world lowpass but did not afford it a
meaningful termination. You can see that if you lower R10 to 100ohms or
less which also makes the hump vanish.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Clifford Heath]

On 24/11/14 18:22, josephkk wrote:

On Sun, 23 Nov 2014 08:29:17 -0800, Joerg <news@analogconsultants.com
wrote:

josephkk wrote:
On Sat, 22 Nov 2014 07:59:41 -0800, Joerg <news@analogconsultants.com
wrote:

It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.

Note to readers of this thread: The designators refer to the posted
LTSpice simulator file, not the displayed schematic.

http://cjh.polyplex.org/electronics/RFCascodeProbe/RFProbeCascodeAmp.asc

To make it run you also have to load the BF862 and BFR93A models into
Notepad each and then store in the same directory where the simulator
file is as BF862.mod and BFR93A.sub.

I can get the circuit to display just fine but even with the files i
cannot seem to get the circuit to "compile" properly. I am doing
something wrong with the fet model. I have all 4 files in a working
directory. Maybe i missed something in file names. The schematic comes
up cleanly.

Here is the log file:
--------------------------
Circuit: * C:\windows\profiles\joseph2k\My
Documents\Downloads\LTSpice\RFProbeCascodeAmp.asc

Error on line 3 : j1 vcc n002 vs jbf862 njf
Unknown parameter "njf"
Direct Newton iteration for .op point succeeded.
.step c6=7e-012
.step c6=1.2e-011
.step c6=1.7e-011
.step c6=2.2e-011
.step c6=2.7e-011
.step c6=3.2e-011

Date: Sat Nov 22 21:19:57 2014
Total elapsed time: 0.188 seconds.

tnom = 27
temp = 27
method = trap
totiter = 7
traniter = 0
tranpoints = 0
accept = 0
rejected = 0
matrix size = 41
fillins = 48
solver = Normal
Matrix Compiler1: 335 opcodes
Matrix Compiler2: 4.37 KB object code size


--------------------------

???=/


As Rick said, it reads in the wrong model. You have to put Clifford's
simulator file into a new directory and then add the two files outlined
above into it, with those exact prefixes and suffixes. Nothing else
should be in that directory. Then start the sim from there.

This is why my server now has a "Heath" directory

One thing that really helps other verify or duplicate sims is to put all
the model information in the simulator file instead of file calls.

OK, i am missing something. I thought that is what i did. Some things
get a little tricky when running firefox in wine via an *ssh* session.

?-)

For what it's worth, I had posted a version here, but the wrapping of
long lines in the models (which I placed inline) defeated some people so
I put it up online.

 

[Robert Baer]

mroberds@att.net wrote:

Martin Riddle<martin_rid@verizon.net> wrote:
Robert Baer wrote:

Like the GC Electronics 19-1902 fer eggzampull?
Need only one bottle, not a case.

19-1902 on Newark $15
19-1902 on ebay $15

19-1902 over the counter at the local electronics distributor, $7.60 +
tax (which is roughly 9%), for roughly $8.30 total.

For stuff like this, you often end up fighting the hazmat charges from
the shippers. Sometimes they charge the same for one can as for as a
case, so it's a little cheaper to let the store order the case and
split up the charge over 12 or 24 cans.

Matt Roberds

Well, i live in Lacey - next door to Olympia.
Olympia is the capital of WA meaning 98+percent work for the Fed, the
state, the county or the city.
The few left say "how do you want your hamburger sir?"
Well, not quite that bad, but...

 

[josephkk]

On Sun, 23 Nov 2014 08:29:17 -0800, Joerg <news@analogconsultants.com>
wrote:

josephkk wrote:
On Sat, 22 Nov 2014 07:59:41 -0800, Joerg <news@analogconsultants.com
wrote:

It is caused by resonance (L1 with the input capacitance) and you can
already see the hump at the output of the first stage J1. When you
remove that inductor the hump is gone. Same when you increase C8.

Note to readers of this thread: The designators refer to the posted
LTSpice simulator file, not the displayed schematic.

http://cjh.polyplex.org/electronics/RFCascodeProbe/RFProbeCascodeAmp.asc

To make it run you also have to load the BF862 and BFR93A models into
Notepad each and then store in the same directory where the simulator
file is as BF862.mod and BFR93A.sub.

I can get the circuit to display just fine but even with the files i
cannot seem to get the circuit to "compile" properly. I am doing
something wrong with the fet model. I have all 4 files in a working
directory. Maybe i missed something in file names. The schematic comes
up cleanly.

Here is the log file:
--------------------------
Circuit: * C:\windows\profiles\joseph2k\My
Documents\Downloads\LTSpice\RFProbeCascodeAmp.asc

Error on line 3 : j1 vcc n002 vs jbf862 njf
Unknown parameter "njf"
Direct Newton iteration for .op point succeeded.
.step c6=7e-012
.step c6=1.2e-011
.step c6=1.7e-011
.step c6=2.2e-011
.step c6=2.7e-011
.step c6=3.2e-011

Date: Sat Nov 22 21:19:57 2014
Total elapsed time: 0.188 seconds.

tnom = 27
temp = 27
method = trap
totiter = 7
traniter = 0
tranpoints = 0
accept = 0
rejected = 0
matrix size = 41
fillins = 48
solver = Normal
Matrix Compiler1: 335 opcodes
Matrix Compiler2: 4.37 KB object code size


--------------------------

???=/


As Rick said, it reads in the wrong model. You have to put Clifford's
simulator file into a new directory and then add the two files outlined
above into it, with those exact prefixes and suffixes. Nothing else
should be in that directory. Then start the sim from there.

This is why my server now has a "Heath" directory

One thing that really helps other verify or duplicate sims is to put all
the model information in the simulator file instead of file calls.

OK, i am missing something. I thought that is what i did. Some things
get a little tricky when running firefox in wine via an *ssh* session.

?-)

 

To: rickman
On Monday, December 8, 2014 6:25:05 AM UTC-5, rickman wrote:

I don't think Propane is terribly expensive. I think most don't have it
just because electric is easier.

--

Rick

I have propane. It is almost as expensive as electricity.

Dan

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To: Bill Sloman
On Monday, December 8, 2014 5:50:00 AM UTC-5, Bill Sloman wrote:

no I'm not. But it will, relatively.

Not forever. There's only so much fossil carbon to dig up, and we are digging

it up a lot faster than it fossilised. And the more we dig up, the more
expensive it gets to dig out the deeply buried stuff that nobody bothered to
dig out before.

So it could remain "relatively cheap" until the real costs of burning it

became obvious to the most dim-witted right-wing nitwit, just before it killed
him (or her).

snip

--
Bill Sloman, Sydney

Fossil fuel will not stay cheap forever. However my grandchildren will
probably die of old age before fossil fuels become expensive.

Dan

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To: Jeff Liebermann
On Sunday, December 7, 2014 11:19:49 PM UTC-5, Jeff Liebermann wrote:

Conventionally, one assumes that the alternative would have been to
invest the money in bonds and assume a certain rate of return.

Which bonds? CD's, treasury notes, and bank deposits are running
about 1.5% AER. Longer term notes are perhaps twice that. If I go
for private placement notes, I might get what the banks are charging
for a 30 year mortgage, or about 3.5% APR. I'll pretend that I'm
lucky and can get 2% APR interest on a 30 year note and take monthly
payments to offset my electric bill. $33,000 over 30 years at 2% is
about $120/month income, or $1,440/year income. Income taxes will
take about 20%, resulting in $1,152 net income.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

$33,000 at 2 % interest is $660 / year or $55 a month. But bonds are not the
only possible investment. Putting $33,000 in a S & P 500 index fund have
historically yielded about $3000 a year or about $250 / month. But not a
consistent income.

Dan

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To: Bill Sloman
On Monday, December 8, 2014 10:50:00 AM UTC, Bill Sloman wrote:

On Monday, 8 December 2014 17:31:38 UTC+11, meow...@care2.com wrote:
On Monday, December 8, 2014 6:14:23 AM UTC, Don Y wrote:
On 12/7/2014 10:22 PM, meow2222@care2.com wrote:

That misses the point completely. No sane person would buy a 100k PV
system sized to run an all electric house when they can spend 5k and
have
gas heating and a well insulated fridge.

You're assuming you can *get* gas at your home. I can think of lots
of places that have electricity but no gas. I can't think of any
that have gas but no electricity!

gas, oil, pellets, random solid fuel, all far cheaper than electric runoff
solar.

[you're also assuming fossil fuel costs remain cheap]

no I'm not. But it will, relatively.

Not forever. There's only so much fossil carbon to dig up, and we are digging

it up a lot faster than it fossilised. And the more we dig up, the more
expensive it gets to dig out the deeply buried stuff that nobody bothered to
dig out before.

There is the point that anthropogenic global warming will probably destroy

advanced industrial society as we know it quite a bit before we've dug up and
burnt all the fossil carbon, so burning fossil carbon for fuel may remain
"relatively cheap" right
up to the point where the side-effects make it impractical to keep on doing it
- in the sense that the climate will have gone west to the point where we can't
grow food like we used to, or extreme weather will have got to the point where
we can't ship
the fossil carbon from where we dig it up to where we wanted to burn it.

So it could remain "relatively cheap" until the real costs of burning it

became obvious to the most dim-witted right-wing nitwit, just before it killed
him (or her).

There are so many holes in that idea I dont know where to begin.


NT

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[Robert Baer]

To: Bill Sloman
Bill Sloman wrote:

On Monday, 8 December 2014 15:19:49 UTC+11, Jeff Liebermann wrote:
On Mon, 08 Dec 2014 13:36:41 +1100, Chris Jones
lugnut808@spam.yahoo.com> wrote:

snip

I'm not so sure. The recent dramatic price drop in Chinese panels,
that has made solar power a reasonable proposition, has also made it a
miserable long term investment. I might expect the cost of panels to
continue dropping in price.

Not logical. The rule of thumb is that if you multiply the manufacturing

volume by a factor of ten, the price per unit roughly halves. The mechanism is
rarely the same from one scale-up to the next, but some ingenious fellow will
find a way.

The Germans did it a few years ago, and put pretty much everybody else out of

business, and then the Chinese did it to them. Solar panels now generate of the
order of 1% of the world's power, so maybe they could generate 10% eventually,
halving the
unit price yet again. Getting another factor of ten growth in manufacturing
scale would have them generating all the world's power, which seems unlikely,
not to mention requiring a spectacularly large - and obvious - investment.

At best, I might build an expandable
array, starting with a few panels and adding more when the price
drops. That's one of the benefits of micro-inverters. The panels do
NOT need to all be identical or even similar. I know of one such
array of mixed panels that is truly ugly, but works just fine.

That might be valuable if you will be
around to take advantage of that free part of the energy, or if you can
find a buyer for your house who places value on that.

The panels certainly add value to a home appraisal, but not if they're
leased:
http://www.npr.org/2014/07/15/330769382/leased-solar-panels-can-cast-a-shadow-over-a-homes-value

Some people also assume that the price of electricity will go up in
future. I won't get into that here.

The cost of electricity has dropped if measured in inflation adjusted
dollars. The reason it seems to be getting more expensive is not that
electricity now costs more to produce, but that the dollar is
shrinking:

http://inflationdata.com/articles/inflation-adjusted-prices/electricity-price-inflation-rate/

Electricity is a particularly negotiable form of energy - you can't store it
(yet) but you can get it to do pretty much whatever kind of work you need.

Did anyone factor in the COST of materials, labor and transportation
for the making of these panels, or is that yet another yet neglected
(and swept under the rug) part that is not supposed to be discussed (AKA
"solar power is FREE")?

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[Lasse Langwadt Christense]

Den mandag den 8. december 2014 19.00.54 UTC+1 skrev Robert Baer:

Bill Sloman wrote:
On Monday, 8 December 2014 15:19:49 UTC+11, Jeff Liebermann wrote:
On Mon, 08 Dec 2014 13:36:41 +1100, Chris Jones
lugnut808@spam.yahoo.com> wrote:

snip

I'm not so sure. The recent dramatic price drop in Chinese panels,
that has made solar power a reasonable proposition, has also made it a
miserable long term investment. I might expect the cost of panels to
continue dropping in price.

Not logical. The rule of thumb is that if you multiply the manufacturing

volume by a factor of ten, the price per unit roughly halves. The mechanism is
rarely the same from one scale-up to the next, but some ingenious fellow will
find a way.

The Germans did it a few years ago, and put pretty much everybody else out

of business, and then the Chinese did it to them. Solar panels now generate of
the order of 1% of the world's power, so maybe they could generate 10%
eventually, halving the
unit price yet again. Getting another factor of ten growth in manufacturing
scale would have them generating all the world's power, which seems unlikely,
not to mention requiring a spectacularly large - and obvious - investment.

At best, I might build an expandable
array, starting with a few panels and adding more when the price
drops. That's one of the benefits of micro-inverters. The panels do
NOT need to all be identical or even similar. I know of one such
array of mixed panels that is truly ugly, but works just fine.

That might be valuable if you will be
around to take advantage of that free part of the energy, or if you can
find a buyer for your house who places value on that.

The panels certainly add value to a home appraisal, but not if they're
leased:
http://www.npr.org/2014/07/15/330769382/leased-solar-panels-can-cast-a-shadow-over-a-homes-value

Some people also assume that the price of electricity will go up in
future. I won't get into that here.

The cost of electricity has dropped if measured in inflation adjusted
dollars. The reason it seems to be getting more expensive is not that
electricity now costs more to produce, but that the dollar is
shrinking:

http://inflationdata.com/articles/inflation-adjusted-prices/electricity-price-inflation-rate/

Electricity is a particularly negotiable form of energy - you can't store
it (yet) but you can get it to do pretty much whatever kind of work you need.

Did anyone factor in the COST of materials, labor and transportation
for the making of these panels, or is that yet another yet neglected
(and swept under the rug) part that is not supposed to be discussed (AKA
"solar power is FREE")?

Materials, labor and transportation is what sets the price of the panels
you imagine the manufacturers sell them for less?

-Lasse

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