Challenge Thread: The fastest breadboard oscillator on the mudball

[mnementh]

joe, OTOH... This is all like watching Master Po and young Kwai Chang Caine discussing discipline in the rock garden... 

Playing with high speed parts is a lot of fun.  You should join the fun.

Ehhhh... I never was a very good engineer, even when I was paid to do it; too weak in the theoretical part and too strong in the hands-on part. Too much cannabis in the off-hours trying to keep my sanity in 1980s-90s corporate borgland deleted the rest to make room for Star Trek and Farscape episodes.



My idea of high-frequency gear nowadays is this... I'm more than content to be a spectator (and occasional commentary) here.   

mnem
 

[joeqsmith]

While your rules will not allow removing or cutting them, we certainly can skip over one to cut the capacitance down.  This helped.

It's really unstable.

Hint: The rules don't forbid shielding. Recycle some tinfoil hats.

Shield for the new oscillator.   For now, it makes a fit contact with the coax.   I would like to add some pins and plug it into the breadboard.   However, if I do this, I would stake it at the reference points only.   It does help with the outside parasitics.   Things like XYZ stages may have less effect..... 

The small part is a detector.   I can tell that the oscillator is running but that's about it.

[joeqsmith]

My idea of high-frequency gear nowadays is this... I'm more than content to be a spectator (and occasional commentary) here.   

Looks like my 189. 

[PA0PBZ]

Here's my try at a minimalistic setup. It took a while because I had to repair the counter first. I don't think it can go any higher without breaking the rule that every connection has to be made via the breadboard. (excluding the SMA, they don't fit well in the breadboard...) So 1 active element and 1 resistor, and if you want to be precise one cap to couple the signal to the counter. The tuned parts are all 'embedded' in the breadboard, that's why I doubt I can get it any higher. I'm sure the power is not there, it runs on 2V 2mA
And yes, the breadboard will never be the same 

[joeqsmith]

Here's my try at a minimalistic setup. It took a while because I had to repair the counter first. I don't think it can go any higher without breaking the rule that every connection has to be made via the breadboard. (excluding the SMA, they don't fit well in the breadboard...) So 1 active element and 1 resistor, and if you want to be precise one cap to couple the signal to the counter. The tuned parts are all 'embedded' in the breadboard, that's why I doubt I can get it any higher. I'm sure the power is not there, it runs on 2V 2mA
And yes, the breadboard will never be the same 

Congratulations and welcome to the 1GHz club!   You're very close to joining the 5GHz club.  That ones a bit more exclusive.   

If you have a way to check the upper frequency limit of your counter and what options it has, could you please post them.   I suspect that mine with no options will start to fold back around 21GHz.  In other words, it seems like as the frequency is increased, the displayed value will decrease.  But I don't have a good way to prove it.   

[PA0PBZ]

If you have a way to check the upper frequency limit of your counter and what options it has, could you please post them.   I suspect that mine with no options will start to fold back around 21GHz.  In other words, it seems like as the frequency is increased, the displayed value will decrease.  But I don't have a good way to prove it.

It doesn't have the power meter, nothing happens when I press the button and the box that supposed to sit behind the N connector entry is not there. I'm not sure about the 24 GHz option, but since the front panel says 18 GHz..? If you send me one of your breadboard oscillators I can try  Are there any other options I'm not aware of?

[mnementh]

My idea of high-frequency gear nowadays is this... I'm more than content to be a spectator (and occasional commentary) here.   

Looks like my 189.

   Good eye.

I had to pare my bench back to just the essentials when I came to the Great White North; everything here either fit in one technician's toolbox or was built/acquired after I arrived. There's a 6022BE bought almost a year ago "to get me by" when I need to do more than count the angry pixies; I keep looking wistfully through the pages of Kijiji & FleaBay for a real wigglescope but no joy at any price I can justify.

mnem
 

[0culus]

While your rules will not allow removing or cutting them, we certainly can skip over one to cut the capacitance down.  This helped.

It's really unstable.

Hint: The rules don't forbid shielding. Recycle some tinfoil hats.

Shield for the new oscillator.   For now, it makes a fit contact with the coax.   I would like to add some pins and plug it into the breadboard.   However, if I do this, I would stake it at the reference points only.   It does help with the outside parasitics.   Things like XYZ stages may have less effect..... 

The small part is a detector.   I can tell that the oscillator is running but that's about it.

Send it to me and I'll throw it on the 8566B 


Where do you purchase copper mesh to make shielding? I would like to get some for a variety of reasons. 

I still have those 5GHz transistors so I will probably do some more experimenting this weekend while I wait for stuff to come.

[joeqsmith]

Send it to me and I'll throw it on the 8566B 

Where do you purchase copper mesh to make shielding? I would like to get some for a variety of reasons. 

I still have those 5GHz transistors so I will probably do some more experimenting this weekend while I wait for stuff to come.

It's a sad day when you find your beloved equipment can't even look at a 50 cent circuit.      I may have to take you up on your offer to test it.  If only LeCroy would send me an old sampling scope...  

I get most of my mechanical parts from McMaster.
https://www.mcmaster.com/mesh

Now that PA0PBZ is nearing 5GHz, you need to start thinking about some 6HGz.      That, and you know all those people with their 10GHz labs we heard of early on are working on taking the lead.   

[temperance]

For those who don't own a fast oscilloscope:

https://en.wikipedia.org/wiki/Lecher_line

An more practical example:
https://hackaday.com/2017/02/07/using-a-lecher-line-to-measure-high-frequency/

There are some Gunn diodes available on Ebay...

[0culus]

Send it to me and I'll throw it on the 8566B 

Where do you purchase copper mesh to make shielding? I would like to get some for a variety of reasons. 

I still have those 5GHz transistors so I will probably do some more experimenting this weekend while I wait for stuff to come.

It's a sad day when you find your beloved equipment can't even look at a 50 cent circuit.      I may have to take you up on your offer to test it.  If only LeCroy would send me an old sampling scope...  

I get most of my mechanical parts from McMaster.
https://www.mcmaster.com/mesh

Now that PA0PBZ is nearing 5GHz, you need to start thinking about some 6HGz.      That, and you know all those people with their 10GHz labs we heard of early on are working on taking the lead.   

thanks for the tip on McMaster.

I just need to order a few things from digikey and minicircuits and I can shoot for beyond 10 GHz.  [edit] I have my carts ready, but not much point in ordering till Sunday at this point in the week.

[BreakingOhmsLaw]

I am guessing that cj's and PA0PBZ's entrys are variant of the Armstrong/Meissner oscillators running purely on parasitics.
For educational purposes, heres one i made. It runs at a measly 2,6MHz - DC really - but here you can see the magnetic coupling of the inductors. It's two coils wound on a small ferite toroid.
See:
https://en.wikipedia.org/wiki/Armstrong_oscillator
The capacitor is omitted in my board, the breadboard measures at 1.5pF between rows.
The real laugh here is that it runs on a voltage as low as 0,765 Volts, and yet outputs nearly 4,6V peak to peak. Black magic! It's really stable as well, hardly any jitter.
Looking at the board, one cannot help to think how the f**k this even oscillates   
Tranny is a BF256B FET.

[joeqsmith]

Taking the new oscillator for a test drive and blowing the old record out of the water and it's only in first gear idling...   

****

Added a scope shot to make it official.

[0culus]

Daaaang. Nicely done. And here I am trying and failing once again to get this stupid 2SC5227 to do anything. Wonder if I killed it.  I have two more...

[0culus]

I got it alive by replicating the circuits I've been playing with already (colpitts), but it's not much faster than what I was doing before (reached 693 MHz). I need to really tweak the inductor, or better yet, find a way to eliminate it and use the parasitics.

[SilverSolder]

What's the benefit/purpose of the copper mesh "cage" around the oscillator?  Wouldn't that just create extra capacitance and lower the frequency?  (RF n00b asks)

[0culus]

Rules clarification: if I manage to get the (erstwhile) second harmonic larger than the (erstwhile) fundamental, can I claim success under the clause "distorting and leeching harmonics"? If so, I finally got something out of the 2SC5227. It's rather unstable and the waveform isn't pretty.

[joeqsmith]

What's the benefit/purpose of the copper mesh "cage" around the oscillator?  Wouldn't that just create extra capacitance and lower the frequency?  (RF n00b asks)

If you watched that early video, I had the Signal Hound monitoring the peak while waving my hand a couple of feet away from it.   The shield helps reduce the sensitivity to changes in the parasitics. 

The problem with this particular oscillator is not making it go faster but how to tell how fast it's going.      

[SilverSolder]

What's the benefit/purpose of the copper mesh "cage" around the oscillator?  Wouldn't that just create extra capacitance and lower the frequency?  (RF n00b asks)

If you watched that early video, I had the Signal Hound monitoring the peak while waving my hand a couple of feet away from it.   The shield helps reduce the sensitivity to changes in the parasitics. 

The problem with this particular oscillator is not making it go faster but how to tell how fast it's going.      

 

Is it possible to beat against another oscillator nearby and pick the difference signal up with the instruments that have run out of breath?

[ogden]

Rules clarification: if I manage to get the (erstwhile) second harmonic larger than the (erstwhile) fundamental, can I claim success under the clause "distorting and leeching harmonics"? If so, I finally got something out of the 2SC5227. It's rather unstable and the waveform isn't pretty.

We (again) are approaching dangerous rule bending territory. Planning to use U9391C or alike in this contest? First you would want to demonstrate spectrogram that includes everything - from DC up-to harmonic of interest so we can see that fundamental indeed is heavily supressed. I would say that if your frequency counter shows harmonic freq instead of fundamental, then it is fair entry.

[0culus]

Dude, will you chill out with all the "dangerous rule bending" crap? This is for fun, no one is playing for money here. Why would I blatantly cheat by using an IC, anyway.  If I was going to do that I could just hook up a microwave sig gen and blow away everyone.  I'm experimenting with different inductor configurations and I happened upon one that made the second harmonic take over by a few dB. All I want is clarification from the OP about how many dB down the the old fundamental ought to be in this situation...

[BreakingOhmsLaw]

Rules clarification: if I manage to get the (erstwhile) second harmonic larger than the (erstwhile) fundamental, can I claim success under the clause "distorting and leeching harmonics"? If so, I finally got something out of the 2SC5227. It's rather unstable and the waveform isn't pretty.

As ogden pointed out, the counter will need to count the harmonic. You will probably need more than 3dB suppression of the fundamental for that to happen.
Bear in mind, with 1.5pF breadboard parasitics, you would need single digit resistance for a 10GHz RC high pass filter.
But i am ready to be proven wrong by voodoo engineering any time! :-D

[BreakingOhmsLaw]

Added a scope shot to make it official.

Is that the new LeCardboyrd scope? Niiiiiice! Looking forward to a full review in TEA.

[ogden]

Dude, will you chill out with all the "dangerous rule bending" crap? This is for fun, no one is playing for money here.

Whatever Dude cool down yourself. I am stirring the pot, for entertainment purposes. Please don't call it Breadboard Oscillator especially when winning entries do not follow rule #3, part "All electrical connections between individual parts must be made by the breadboard contacts".

Why would I blatantly cheat by using an IC, anyway. 

Usually main part of Comb Generator is just diode. Thou needs powerful signal. Anyway I was kidding. Noticed smiley that looks like: ? It means: "laugh". Comprehend?

I'm experimenting with different inductor configurations and I happened upon one that made the second harmonic take over by a few dB.

Good! As I said - would be nice to show fundamental together with harmonic, preferably using two markers, if any.

[0culus]

Rules clarification: if I manage to get the (erstwhile) second harmonic larger than the (erstwhile) fundamental, can I claim success under the clause "distorting and leeching harmonics"? If so, I finally got something out of the 2SC5227. It's rather unstable and the waveform isn't pretty.

As ogden pointed out, the counter will need to count the harmonic. You will probably need more than 3dB suppression of the fundamental for that to happen.
Bear in mind, with 1.5pF breadboard parasitics, you would need single digit resistance for a 10GHz RC high pass filter.
But i am ready to be proven wrong by voodoo engineering any time! :-D

Fair enough. My sleep deprived brain came up with this monstrosity.  The fundamental and second harmonic are essentially equal, but sadly the second harmonic is already getting pretty far outside the 7104 (and FET probe's) passband so I can't see what it looks like in time domain with my current tools. Basically, it's the same Colpitts oscillator except with the 2SC5227 transistor (which had already been helpfully mounted in a tiny PCB with legs for breadboarding) and this train of inductors that aren't directly in the circuit but are modifying the parasitics.