Search results

Demonstrates the essential steps for winding **toroidal cores**, a fundamental skill for amateur radio operators engaged in homebrewing and kit building. It addresses the critical aspects of selecting the correct core material and wire gauge, emphasizing the importance of precise turn counting and consistent winding tension to ensure optimal circuit performance. The resource details methods for preparing the wire, including techniques for safely removing enamel insulation from leads using flame, sandpaper, or a solder pot, and provides guidance on tinning the exposed wire. Explains the process of mounting the wound toroid onto a printed circuit board, highlighting the need for careful lead placement and secure soldering to prevent shorts and ensure mechanical stability. It also offers a practical formula for calculating the required wire length based on the desired number of turns and the specific **toroid** size, referencing common core types like T-50 and FT-240. The guide stresses the importance of verifying the inductance of the wound component, often using an inductance meter, to confirm it matches design specifications. Provides practical tips for handling multi-filar windings and managing short lead lengths, which can be particularly challenging. It underscores the necessity of meticulous attention to detail throughout the winding and installation process to achieve reliable and efficient RF circuits.

Online calculators for toroid coil, air-core coil inductance, XL, XC, and more.

To save a little time from calculating and experime nting when winding toroid cores here a chart of the most commonly used cores

Select the toroid by material type and dimension of the toroid, the desired inductance and you will get the numbers of turns

The MFJ-971 portable antenna tuner, as stock, lacks a bypass switch and sufficient inductance for efficient 1.8 MHz operation. This modification addresses these limitations by integrating a DPDT switch for direct signal bypass, enhancing operational flexibility. Furthermore, the guide details the addition of a T130-2 iron powder toroid, wound with **29 turns** of enamelled copper wire, to augment the tuner's internal inductance. This increases the maximum inductance from approximately 17µH to around **27µH**, enabling effective impedance matching on the _160-meter band_. The modification involves cutting the wire after the 'L' tap on the original inductor and inserting the additional toroid, ensuring the entire original coil plus the new inductance is engaged when 'L' is selected. This preserves the functionality of other inductance settings while extending low-band performance. The article also highlights a potential RF burn hazard from the variable capacitor nuts on the MFJ-971, even at QRP power levels.

This RF Toroid Calculator provides graphical calculator used to determine the inductance and other parameters of ferrite and powdered-iron toroids. It simplifies the process of selecting the appropriate toroid for use in radio frequency (RF) circuits

Online impedance calculators grouped by types like Wire inductances, Toroid incuctances, Plane, PAD, Strap inductances, but even Core and Coax Inductances. Air core inductances and mutual inductance groups are also availbale. All these calculators let you input specific paramenters based on the inductor selected and will calculate specific incutance and related dimensions.