Variable Capacitor 65pF + 145pF With Mounting Screws

This is one item of new, dual gang miniature tuning capacitor with a solid polyethylene dielectric as shown in the pictures. Two M2.5 screws are included for panel mounting along with two loose nuts which allow for spacing behind thin panels. A further screw and loose nut can be screwed into the shaft for fixing a control, or for using like a large value trimmer. The case measures 21 X 22 X 13mm. The screws may foul the internal parts if screwed in too far without using the spacer nuts provided.

The middle connection is the common ground terminal for the two sections. The terminal next to the C3 mark is the 65pf section. The terminal next to the C4 mark is the 145pF section. You can connect the two outer connections together to make a variable capacitor of 210pF in total. The minimum capacitance of C3 is approximately 4pF. The minimum capacitance of C4 is approximately 5pF. There are two trimmers on the back. When the C3 trimmer is fully meshed this adds about 12pF capacitance. When the C4 trimmer is fully meshed this adds about 14pF. The trimmers are used to make up stray capacitance to set up the tracking in superhet radio designs. The shaft rotation is 180 degrees.

You can use these in crystal sets, TRF, regenerative radios and receiving loops where the trimmers are best set for minimum capacitance with the plates fully un-meshed. These are not suitable for transmitting loops. The long connection terminals allow the easy use of 3A mains terminal block connectors to attach wires without soldering.

Here are some project examples:

MW / LW AM Radio Resonant Signal Boosting Loop Aerial

The HJW Electronics Choccy Block Crystal Set Radio Kit CBCSRK-1T

The HJW Electronics Breadboard Six Transistor Radio Kit BBRK-1

This variable capacitor is also available with a shaft extension and a suitable knob on another listing.