Dr Ronald Stiffler SEC technology

[Lidmotor]

erfandl---I am using an MPSA06 just fine on mine.  It gets warm at the higher voltages but I have not blown one yet.  A little Al tape "wing" heat sink is all I need.  At 50mA the little transistors can handle this situation. We can use the bigger transistors that we both have if we need to.
Your English is OK.  No problem.

Gyula---Thanks for the links to the subject matter that we are discussing.  That was helpful.  Thanks also on how to pronounce your name ('due' -'la'). 

--Lidmotor

[itsu]

Hi Itsu,

Okay, so it seems your SA nicely shows the multiple output frequencies of an RF mixer and we can be sure the displayed amplitudes at their specific frequencies are present at the collector of the transistor, it is reality.

Regarding your 12 MHz crystal needed a higher input current: although there is the so called 'activity' (willingness to oscillate) behaviour for crystals in general (they are all 'different'), have you tried this: just start the same oscillator with a single 12 MHz crystal and try to run it with say 15-20 mA input current only to see how it behaves. If it is willing to oscillate 'normally', then plug in a single 13,56 MHz crystal in parallel with it and see it oscillate or not etc. Of course it is possible you find the need for increasing input current again to have both crystals work, you will see. Try a 2nd or 3rd 13.56 MHz xtal (one by one) instead of the first one if you find the need for increasing input current to have both crystals work.
And if you happen to have other crystals of yet differing frequencies, do test them when you have time.

We may deduce from your tests now why the SA is not able to display the multiple output frequencies of the 2 or 3 or 4 or 5 pieces of the 13.56 MHz crystals in parallel: the outputs of the frequency components due to the mixing process simply coincide. This means that say the sum of two 13.56 MHz xtals is simply almost equal to the 2nd harmonic, 27.12xx MHz, the small difference may range from some 10 Hz to some 100 Hz (up to some kHz at the higher harmonics) only, so that the SA resolution is simply not fine enough. I think it is the RBW (Resolution Band Width) setting on the SA which can only be reduced to a given smallest setting. depending on sweep time (SWT) or frequency span etc.  The RWB was set to 30 kHz on your SA when you zoomed in on the 13.56 MHz frequency and probably a 10 Hz or less RBW would be needed to see the different frequency components which differ from each other by say 34 Hz. Of course this 10 Hz RBW or less may be a strict requirement for an SA, though not impossible.   

Thanks, 

Gyula

Gyula,

i put the 100K trimmer pot all the way up (100K) and let the oscillator run using a single 13.56Mhz crystal.
It pulls about 14mA giving moderate light at the leds (output voltage about 32Vpp).

Adding a 12Mhz xtal does not do anything, only when pulling out the 13,56Mhz xtal, the oscillator starts
running on 12Mhz, input current increases somewhat (14.4mA) and the leds shine somewhat brighter (output voltage still around 32Vpp).

Adding again the 13.56Mhz xtal again does do nothing untill pulling out the 12Mhz xtal, then the osc. flips
over to 13.56Mhz, decrease the current to 14mA and lowering the leds light (output voltage stays the same).

Doing the same with a 10Mhz xtal shows the same but more extreme, adding the 10Mhz xtal does nothing untill
pulling out the 13.56Mhz xtal, than the leds are more brighter (more then the 12Mhz xtal), input current
goes to 16mA but output voltage stays the same.


To get the both xtals work (mixing), i have to increase the input current to between 50 and 70mA depending
on the xtals in use.

All kind of patterns emerge on both the SA and the scope when mixing is active 

Itsu

[mikrovolt]

Most of you are familiar with Dr Stiffler's methods. We imitate, "Do just like that" we get certain results. It bridges gaps previously
not obvious because of experience level. ln this post the video uses a different method in working with a roll of coax. 
Stepping back for a moment from single wire. Looking at coax with multiple frequency Will the faster wave arrive sooner?
The crystal has a constant frequency however the length of the coax has a set distance that gives a time constant.
We identify these constants and their artifacts gives us an advantage in using them effectively. The multiple frequency
waves could be untangled easier using a few basics for making sense of waveforms with it's reflected wave when
the nodes are fixed. The applications in alt energy are many. Only a few are applying this concept in various applications.
I see the potential with in this thread to advance understanding why concept like this are useful in open systems.

The concept of terminating a coax by adjusting the terminating resistance using a potentiometer. Keeping this simple
by using only a single frequency we can see the constant artifact on the scope and adjustment is made to restore
a distorted signal for a given impedance load. The concept of the cable length will have a fixed time constant.

So at a frequency of 13.6 Mhz, no coax, broadcast into an aluminum back plane we can appreciate that methods were shared.

Revisiting the time constant and potentiometer on a roll of wire with two conductors:  https://youtu.be/zrDxSM91Jcg

There are some simulations showing multiple frequencies. We can get a visual idea what they look like.
We can see the multiple signals have synchronous pattern, in one case the waves resembles something like a roller coaster.
page down look for subtitle play: 
Appendix A: What happens if the amplitudes are not equal?
Appendix B: What happens if the frequencies are not equal?

http://qr.ae/TUIFJy

[TinselKoala]

Transmission line model demonstration:
https://www.youtube.com/watch?v=f4T5KKQjz0s

[mikrovolt]

Regarding self resonant frequency and the 3 coil system earlier I was incorrect
I need to make a correction here.

Sorry that should be Spatial Self Resonance
please refer to video for correct method

https://youtu.be/6FOq7-WsL5c
https://youtu.be/l9q_r5_jEP4