+
+
Notes:
+ The VK3CPU RF Transformer Calculator was developed to help users predict the RF characteristics of a ferrite toroid wound as a transformer.
+ It uses the manufacturer's (Fair-Rite) published data including the toroid's dimensions and complex permeability characteristics
+ to predict the component's characteristics.
+ The calculator has 3 separate display areas. At the top is the chart display for showing frequency-dependent characteristics. Next is the
+ schematic display, where a scaled image of the toroid and windings is presented to help with intuitive design. Next is the control panel
+ section, where the user can select the application type, toroid material, toroid size, wire size, number of windings and excitation voltage.
+
Inputs via the select widgets:
+
+ - Application : Selects the intended use of the toroid, either Inductor or Suppressor is currently supported. This limits the material selection as appropriate.
+ - Size : Selects the size of the toroid. FT240 is 2.4" in diameter. FT80 is 0.8", etc...
+ - Material : Manufacturers material mix code. Inductor mode shows initial permeability [μi] in square brackets. (Pick lower μi for higher frequency applications.)
+ Suppressor mode displays effective suppression frequency range in square brackets.
+
+
Inputs via the slider widgets:
+
+ - AWG : Select the wire gauge. Sliding L-R changes AWG from 40-0. (Defaults to 20 AWG)
+ - N : Winding density at the toroid inner-diameter. Controls how many single-layer turns can be achieved around the core.
+ Maximum (100%, slider to hard-right) is reached when the turns are adjacent at the toroid's inner radius. (Defaults to 15%)
+ - Vrms : The RMS voltage applied to the inductor (Volts). Determines the flux-density (B) and field-intensity (H) within the ferrite toroid. (Defaults to 10Vrms)
+ - f : Shifts the frequency of interest of the chart display from left-to-right. Left towards kHz, right towards GHz.
+
+
Note: Manufacturers recommend keeping the number of turns (N) to a minimum.
+
Chart display:
+ The chart title contains manufacturer, size, material and part number of the device.
+ Calculated parameters are displayed against frequency (log scale). Each parameter may be displayed or hidden
+ by tapping on the legend key. Tapping on a data point will display the parameters for a single frequency.
+
+ - L(μH) : Inductance in microhenries.
+ - |Z|(Ω) : Impedance magnitude in Ohms.
+ - X(Ω) : Reactance in Ohms.
+ - R(Ω) : (F) - Resistance due to core losses in Ohms.
+ - Rc(Ω) : (PI) - Resistance due to core losses in Ohms.
+ - Rw(Ω) : (PI) - Resistance due to wire losses in Ohms.
+ - Q : Quality factor. (X/R)
+ - I(mA) : RMS current in milliamps.
+ - μ' : (F) Complex permeability - reactive part. (Hidden by default.)
+ - μ'' : (F) Complex permeability - resistive part. (Hidden by default.)
+ - μ : (PI) Permeability (Hidden by default.)
+ - H(Oe) : Core field intensity in Oersted. (Hidden by default.)
+ - B(G) : Core flux density in Gauss. (Hidden by default.)
+ - Pd(mW) : Sum of the power dissipation in the core, in milliwatts. For PI, it includes power dissipated in the wire also.
+
+
+
Schematic display:
+ Scaled representation of the toroid and the windings. Wire gauge and toroid dimensions are provided.
+ On the left of the display are the following:
+
+ - Lᵢ : Initial inductance in microhenries. This is based on the initial permeability figure found in data sheets. For accuracy, use the frequency-dependent inductance displayed in the chart.
+ - Vrms : Excitation RMS voltage selected.
+ - Rdc : Wire resistance in ohms.
+ - Ceff : Experimental effective-capacitance calculation to determine SRF. (Under development so greyed-out. Based on David Knight's G3YNH
+ work on the self-capacitance of toroidal inductors detailed HERE).
+ - SRF : Experimental self-resonant frequency prediction in MHz. (Under development so greyed-out. From the same paper detailed above.)
+
+ In the middle of the display are the following:
+
+ - nn AWG : The wire gauge selected, based on the American Wire Gauge Standard.
+ - ⌀ : Conductor diameter in mm and (inches).
+ - Nd : The selected winding density in percent.
+ - N : The number of turns, based on the selected Nd.
+ - wire : Wire conductor length in centimeters and (feet).
+
+ On the right are the manufacturers data for the selected material.
+
+ - μi : Initial permeability @ B < 10 gauss.
+ - B : (F) Flux density in gauss when applied with H oersted.
+ - H : (F) Applied field strength in oersted.
+ - Bsat : (PI) Saturation flux density in gauss.
+ - Br : Residual flux density in gauss.
+ - Hc : Coercive force at 0 gauss.
+ - Tc : Curie temperature in Celsius.
+ - ρ: Resistivity in Ω-cm.
+ - Type : Material composition. (NiZn, MnZn, Phenolic, Carbonyl)
+ - P/N : Manufacturer's part number.
+
+
+
Observations:
+
Powdered Iron:
+ Inductance and reactance values correspond well with those predicted by online calculators such as toroids.info.
+ However, predictions for Q have mixed results when compared to the Micrometals Q-Curve Catalog found
HERE.
+ I suggest using their catalog for accurate Q prediction. It has been previously identified that Q values predicted using Micrometal's curve-fit equations do not reconcile with measured Q as discussed
here.
+
+
Other VK3CPU calculators:
+
+
+
+
TODO:
+
+ - Add a DC current bias slider.
+ - Consider adding temperature slider.
+
+
+
Change history:
+
[2-May-23] - v0.5
+ * Added 2646102002 which I have called the "FT102B-61"
+