making a frequency doubler circuit, want another set of eyes on it

[iMo]

1. the 2N3904 is not a high freq transistor, you should use a different one (w/ Ft>1-3GHz)
2. the "impedance matching" between the stages is important in ALL your circuits above (I do not see any matching there)..

[Kyle_from_somewhere]

1) If this transistor isn't suitable, then what is?

2) To match impedance, you must know what the impedances are. I don't. I can't find out how to find out.

If you don't bother explaining your remarks, they are useless.

[iMo]

Do not expect people will be elaborating pretty obvious stuff.. 

PS: Input/output impedance of a circuit - for example do google "LTSpice input output impedance measurement"

[Gerhard_dk4xp]

removed the text.
no point in trying to help someone without basic knowledge
who holds others responsible for it.

[Kyle_from_somewhere]

There's no BAT15 in LTspice. Can't find anything to download to add one either. So I've left it at 1N4148 until a better option presents itself.

Adding 1uH from output to ground just slows output down to 107 Mhz.

[Kyle_from_somewhere]

removed the text.
no point in trying to help someone without basic knowledge
who holds others responsible for it.

When I ask a question and a man replies "i don't want to explain something so obvious" then it is his responsibility. I did my part by asking.

Sorry that I didn't come from the womb knowing all the things that you find are so obvious.

[RoGeorge]

Do not expect people will be elaborating pretty obvious stuff.. 

You're going on my ignore list for being a deliberately unhelpful dickhead.

And you go to everybody else's ignore list, starting with mine.

And if you don't have the knowledge to understand the answers here, then you should have asked for clarification, and not start calling names.  Adios!

[Kyle_from_somewhere]

And if you don't have the knowledge to understand the answers here, then you should have asked for clarification, and not start calling names.  Adios!

I did. As you know (because you can read), he refused to clarify.

Glad to no longer see you around, whoever you are.

[TimFox]

There's no BAT15 in LTspice. Can't find anything to download to add one either. So I've left it at 1N4148 until a better option presents itself.

Adding 1uH from output to ground just slows output down to 107 Mhz.

The 1N4148 has a reverse recovery time of 4 to 8 ns, depending on current.  That won't work well at your frequencies.  The BAT15 is a Schottky diode rated for GHz operation.

Maybe try an 1N5712 Schottky or similar.  This link has a datasheet and a Spice model.  https://www.farnell.com/datasheets/89202.pdf

[Kyle_from_somewhere]

The "spice model" is a table. How do I enter it into LTSpice?

[TimFox]

I don't use LTSpice, I use Spice.  Those are the normal co-efficients for a diode model in Spice.
Check the documentation on LTSpice on how to enter the model co-efficients.
Perhaps you can find what you need about these diodes somewhere by Googling.
This took me 30 seconds:  https://ltwiki.org/files/LTspiceIV/Vendor%20List/Diodes%20Incorporated/Spice/spicemodels_schottky_diodes.txt

[Kyle_from_somewhere]

I don't use LTSpice, I use Spice.  Those are the normal co-efficients for a diode model in Spice.
Check the documentation on LTSpice on how to enter the model co-efficients.
Perhaps you can find what you need about these diodes somewhere by Googling.
This took me 30 seconds:  https://ltwiki.org/files/LTspiceIV/Vendor%20List/Diodes%20Incorporated/Spice/spicemodels_schottky_diodes.txt

Okay, but you could have spent less than 30 seconds to say "i don't know, sorry" instead of posting a random file you didn't actually look at and pronouncing yourself the king of google.

If you'd looked at it, you'd see nowhere is something like "1.1 x 10E-9" able to go.

Hell, if you'd looked at the PDF you'd posted you'd know there isn't even Spice parameters for the diode you mentioned, only other ones.

[TimFox]

The very first entry in that link is the model for a 1N5711, which was referred to in my earlier link along with the 1N5712 and other similar devices.
Apparently you only looked at that link and did not understand it.

  ".MODEL DI_1N5711 D  ( IS=315n RS=2.80 BV=70.0 IBV=10.0u
   + CJO=2.00p  M=0.333 N=2.03 TT=1.44n )   "
is the Spice model.  What do you see when you examine your LTSpice model, which should be a text file.

I can't do all your work for you, does that make me nasty?
OK:  besides YouTube videos on this very topic, I found
https://electronics.stackexchange.com/questions/397354/how-can-i-convert-pspice-model-into-ltspice-model

[Kyle_from_somewhere]

The very first entry in that link is the model for a 1N5711, which was referred to in my earlier link along with the 1N5712 and other similar devices.
Apparently you only looked at that link and did not understand it.

  ".MODEL DI_1N5711 D  ( IS=315n RS=2.80 BV=70.0 IBV=10.0u
   + CJO=2.00p  M=0.333 N=2.03 TT=1.44n )   "
is the Spice model.  What do you see when you examine your LTSpice model, which should be a text file.

A completely different format:

Code: [Select]

.model 1N914 D(Is=2.52n Rs=.568 N=1.752 Cjo=4p M=.4 tt=20n Iave=200m Vpk=75 mfg=OnSemi type=silicon)
.model 1N4148 D(Is=2.52n Rs=.568 N=1.752 Cjo=4p M=.4 tt=20n Iave=200m Vpk=75 mfg=OnSemi type=silicon)
Copy and paste what you said into LTSpice and nothing happen. Copy and paste it into the diode file of LTSpice with notepad: nothing happens, no new diode is avaliable to use.
Save entire text file you linked and open it in LTSpice: LTSpice does not understand the file format.

I can't do all your work for you, does that make me nasty?
OK:  besides YouTube videos on this very topic, I found
https://electronics.stackexchange.com/questions/397354/how-can-i-convert-pspice-model-into-ltspice-model

You haven't even done your own work. For one, there are no youtube videos showing how to enter a table of spice parameters from a datasheet into LTSpice. I know because I looked. If you search for them, you get people modelling ICs from datasheets without spice parameters in them. Or you get a guy showing how to create spice parameters from scratch using very long physics formulas, but not how to enter them into the program.

Then you link stackexchange thread about converting ready working model files from pSpice, which is also nothing to do with it.

As I said, if you don't know, it is OK, just say you don't know. Don't give wrong advice and then get mad I say it doesn't work.

[Kyle_from_somewhere]

Let it be a lesson to us all: if you ever want to accuse someone of not knowing how to look stuff up, don't be like timfox. Don't fling random links you haven't checked.

[TimFox]

There are other Schottky diodes in the LTSpice library.  I couldn't find the 1N5711, but I gave you the Spice parameters from two sources.
Have you tried real Spice?
I have grown bored with this discussion.
I got along without you, before I met you, gonna get along without you now.

Let this be a lesson to all of you out there:  this guy can't be satisfied even with real data, if he doesn't understand it.

[Kyle_from_somewhere]

I have grown bored with this discussion.

No, I don't think you got bored. I think you're the typical tech expert elitist on the internet. You can't answer simple questions because you think they're below you, and you DEFINATELY can't admit that there are some things you don't know, because that would damage your self image as an electronics demigod (This is also why you brag about only using "Real" spice, presumably meaning the one that was released so long ago no modern computer can natively run it).  So instead you just scream the mantra of "google it" as if the person you're talking to didn't.

Here today you embarrassed yourself by throwing google results at me without bothering to read them yourself to see if they're applicable.

So, you do what everyone who embarrasses himself on the internet does: you're trying to play it off with an air of superiority. I'll give you some credit, you went with the faux upper class "i have grown bored of you", rather than the more typical "i'm not mad, I'm laughing actually".


Seriously, you could've just said "Sorry, I don't know how to do that in LTSpice", instead of this.

[TimFox]

No, I am not an expert on LTSpice.
I suggested that 1N4148 was not a good choice for your circuit, and recommended 1N5711, 1N5712, etc. instead.
I sent you two sites with legitimate Spice models for 1N5711-type Schottky diodes, but all I got back was rude abuse.
Since you use LTSpice, I assumed you knew how to use it.
Good bye.

[Kyle_from_somewhere]

I sent you two sites with legitimate Spice models for 1N5711-type Schottky diodes, but all I got back was rude abuse.

No actually that's not what happened, Tim. I asked you what to do with the data provided, then you snottily took on airs:

Perhaps you can find what you need about these diodes somewhere by Googling. This took me 30 seconds

The "this" in question was a text file that does not work in LTSpice, but you thought that it did because all you'd done is read the URL and assume. That's on you.

You really shouldn't act so smug about your superior googling ability when it gets you wrong answers.

[TimFox]

That text file in my second link was a data library containing another normal Spice file for the 1N5711.
You didn't read it, or you would have noticed "1N5711".
'bye!

[Kyle_from_somewhere]

I did notice 1N5711, you should know this because I told you I attempted to get LTSpice to load it.

You shouldn't go around accusing others of not googling when you can't google properly, accuse others of not reading when yourself haven't read, etc etc

Or keep saying "bye" and then coming back.

[TimFox]

I only do it to annoy,
Because I know it teases.

(L Carroll)

[Kyle_from_somewhere]

I only do it to annoy,
Because I know it teases.

(L Carroll)

So, you do what everyone who embarrasses himself on the internet does: you're trying to play it off with an air of superiority. I'll give you some credit, you went with the faux upper class "i have grown bored of you", rather than the more typical "i'm not mad, I'm laughing actually".

You blew it.

[Kyle_from_somewhere]

Right then, now that the ignore list has it's fourth member...

Anyone is welcome to participate in my threads, on the condition that questions are answered to the best of a healthy person's ability. "I don't know" is an okay honest answer.

If being smug about how the question is "too obvious to answer", talking nonsense because you haven't read the thread properly, making declarations of your own superior googling ability, etc are answers to the best of your ability, then you have a personality disorder and aren't healthy enough to participate. You will go straight on ignore.

Since we're on a new page, I'll repeat the last post made before the freakshow showed up and attempted to ruin everything.

[Kyle_from_somewhere]

The example I'm thinking of is this TV transmitter project, Radio Electronics Magazine June/july 1989

Part 1: https://archive.org/details/radio_electronics_1989-06/page/n37/mode/2up?view=theater

Part 2: https://archive.org/details/radio_electronics_1989-07/page/n41/mode/2up?view=theater

I've clipped the relevant part of the diagram. For some reason the authors think themselves above specifying inductance (why is this so common?), but they're successfully using a chain of transistors to double the frequency. I tried to upload the coil table but there are too many artifacts in the image to make a file small enough.

Learning things like how to bias a transistor for a particular result is very difficult because the internet makes for a bad educator. It's easy to stumble across a hundred youtube videos with a title like "how to bias a transistor", but every single one just has an overcaffinated guy with a whiteboard start by pulling two resistor values out of his ass, calculating the last two based on them, and then declaring it done. No explanation of what makes it linear or non linear, in fact no mention of the concept of a transistor operating linearly or not, just "it's biased now, don't forget to click like and subscribe".

Trying to find something written down using google is even worse. You fall into forum threads where the youtube scenario is repeated almost word for word, followed by someone saying to use an op-amp instead - without even the courtesy of explaining how. Just like here I'm told to use a transformer and two diodes, without being told how.

I don't want to just blindly copy someone else's circuit because often they're ancient and the parts aren't made anymore, and even if they were available I don't learn anything. But It's also difficult to learn to design my own circuits when the only "education" I can access is people doing stuff without explanation, or people saying "do something else instead" also with no explanation. I cannot go to university.