Variable Capacitor 4 Gang AM FM 266pF 20pF X2 Knob Screws 500pF Total

This is one item of new variable capacitor comprising two 266pF AM sections and two 20pF FM sections.

All the sections can be connected together if required to create 572pF in total for receiving loop antennas or for a crystal set tuning capacitor which calls up 500pF. The matching 266pF sections allow use in low power Z-match type antenna matching circuits.

Two M2.5 screws are included for panel mounting along with two loose nuts which allow for spacing behind thin panels. The mounting screws must not go into the body too far or the FM capacitor sections will be damaged. There is also a shaft extension included which is secured onto the shaft with another M2.5 bolt. This is a simple 6mm diameter polystyrene spacer which works really well as a shaft extension and allows the use of standard grub screw knobs.

A suitable 24mm diameter 6mm shaft knob is included in the kit. This fits on to the shaft extension and is secured using a standard flat bladed grub screw in the side of the knob. The knob is 20mm tall and this allows it to either cover the shaft completely when mounted on thin panels or to stand off some way when mounted on thicker panels. This kit is available without the knob on another listing in the shop, where you can also find a similar style 16mm or 35mm knob if required.

The trimmer capacitors C1 to C4 on the rear measure about 15pF maximum. These C1 and C2 are internally connected across the two FM sections but C3 and C4 have separate external connections rather than internal connections to the AM sections. All the connections have long, easy to solder tabs or they can even be connected without soldering using 3A terminal block connectors. Connection diagrams are shown in the pictures.

Connection Diagram Key

A Common (GND)
B VC1, 20pF + C1 15pF trimmer, FM
C Common (GND)
D VC2, 20pF + C2 15pF trimmer, FM
E VC4, 266pF, AM
F VC3, 266pF, AM
G C4, 15pF trimmer
H Common (GND)
I C3, 15pF trimmer

Headline Specs

Maximum voltage: 100V d.c.
Mounting bolts: M2.5, 6mm length provided
Mounting bolt separation: 14mm
Shaft securing bolt: M2.5, 15mm length provided
Overall box dimensions: 22 x 22 x 17mm
Height inc shaft: 21mm
Shaft length: 4mm normal, 16.5mm with extension