When we are talking about wave forms such as AC, acoustic, Audio, RF or otherwise, the fundamental principles of impedance matching remain identical across the board. Those principles are always based on the carrier wave of such a signal as the fundamental wave form to be matched and any residual waves such as modulations and time delays will not become a factor in the tuning of such a signal.
If you have a AM radio frequency for example and a dipole antenna, the source impedance must be matched to the antenna so that none of the signal is reflected back at the source in the form of standing waves. In the case of RF oscillations the source impedance of most radio's is 50ohms. The antenna impedance on a dipole is 75ohms which is a mismatch, so we use a balun to match the impedance.
In the case of a end fed vertical antenna things change drastically. On a frequency of 15mhz for example, the impedance of the antenna at that frequency is about 1000ohms and you end up with a massive mismatch. The easiest way to rectify this is that you place a dc ground coil across the terminals of the antenna at the feed point and you tap into the 50ohm point in the coil. The inductive and capacitive reactances cancel each other out at resonance when you do this. Stan's negative choke is doing the exact same thing. This tells us right away that the value in ohms of Stan's tubes is far higher than his source impedance at resonance on some of his designs.
To tune Stan's tubes, all you need to do is run the fundamental frequency at low voltage through the VIC and cell and on the negative choke which is variable adjust the inductance until you find the source impedance which you are entering into your primary at 3980hz. That's it, you don't need to do anything else bar never run the system at full voltage straight away, make sure you increase the voltage into the primary steadily so that the PLL can easily keep up with the system.
So how is Stan tuning his alternator variac design when you can't alter the variac and alternator dc ground state? Well, the answer lies in the source impedance compared to the load impedance and the according radio, because the source impedance is absolutely fixed then you can do it two ways:
If the cell impedance is lower than the alternator source impedance you can play around with a gamma match, a gamma match can only work if you are trying to increase the impedance of the cell and it works by changing the capacitive reactance. You have a tube capacitor which is basically one tube inside another with teflon as a dielectric layer which is on the outside of the cell, this is placed in parallel to the cell and as you slide the tube capacitor in or out the reactance of the cell changes and so does it's impedance. It is exactly same as the dc ground but works on capacitive reactance rather than inductive reactance.
The other way you can tune the cell on the alternator set up is to use the tubes themselves as a match. you cut the tube length so that the impedance is a match to the alternator impedance, this has to be done in batches of three to match each phase of the alternators three phases. You would of course have two tubes out of every three right in the ball park then every third tube would be a fine tune at 3980hz resonance.
If you have a AM radio frequency for example and a dipole antenna, the source impedance must be matched to the antenna so that none of the signal is reflected back at the source in the form of standing waves. In the case of RF oscillations the source impedance of most radio's is 50ohms. The antenna impedance on a dipole is 75ohms which is a mismatch, so we use a balun to match the impedance.
In the case of a end fed vertical antenna things change drastically. On a frequency of 15mhz for example, the impedance of the antenna at that frequency is about 1000ohms and you end up with a massive mismatch. The easiest way to rectify this is that you place a dc ground coil across the terminals of the antenna at the feed point and you tap into the 50ohm point in the coil. The inductive and capacitive reactances cancel each other out at resonance when you do this. Stan's negative choke is doing the exact same thing. This tells us right away that the value in ohms of Stan's tubes is far higher than his source impedance at resonance on some of his designs.
To tune Stan's tubes, all you need to do is run the fundamental frequency at low voltage through the VIC and cell and on the negative choke which is variable adjust the inductance until you find the source impedance which you are entering into your primary at 3980hz. That's it, you don't need to do anything else bar never run the system at full voltage straight away, make sure you increase the voltage into the primary steadily so that the PLL can easily keep up with the system.
So how is Stan tuning his alternator variac design when you can't alter the variac and alternator dc ground state? Well, the answer lies in the source impedance compared to the load impedance and the according radio, because the source impedance is absolutely fixed then you can do it two ways:
If the cell impedance is lower than the alternator source impedance you can play around with a gamma match, a gamma match can only work if you are trying to increase the impedance of the cell and it works by changing the capacitive reactance. You have a tube capacitor which is basically one tube inside another with teflon as a dielectric layer which is on the outside of the cell, this is placed in parallel to the cell and as you slide the tube capacitor in or out the reactance of the cell changes and so does it's impedance. It is exactly same as the dc ground but works on capacitive reactance rather than inductive reactance.
The other way you can tune the cell on the alternator set up is to use the tubes themselves as a match. you cut the tube length so that the impedance is a match to the alternator impedance, this has to be done in batches of three to match each phase of the alternators three phases. You would of course have two tubes out of every three right in the ball park then every third tube would be a fine tune at 3980hz resonance.