Frequency: 144-146MHz
Type: 3x5/8 wavelength
Gain: 7.8dB
Maximum power rating: 100W
Impedance: 50ohms
Length: 4,2m
VSWR: Less than 1.5:1

Summary
The F23 pocket antenna is based on the Diamond F23 design. It’s designed to work as a 3x5/8 wave for a 144-146MHz band, but using the Diamond tuning table, it can be tuned to other frequencies, too (see manufacturer's documentation).

Description
The antenna consists of three coils connected by a radiator wire. Full dimensions and electrical connections can be seen in the attached diagram. The copper wire I used for all the coils has a cross-sectional area of 1.5 mm2, but it can be thinner, though. The radiator I used in the original project was made from a military phone cable used by Eastern Block armies. The capacitor connected to the RF socket with a matching coil was like in an original project (8,2pF 500V) but feel free to use any capacitor with the capacitance between 5 and 10pF rated for 500V.

Assembly
The bottom/matching coil consists of two parts: coil (bottom_coil.stl) and SO239 mount (bottom_mount.stl). After assembling the matching coil, the bottom wire should be passed through the hole in the SO239 mount and bent to be squeezed with the SO239 socket - this way you make a good connection between the SO239 socket and matching coil. After soldering both parts should be glued together.

Parts list:

1. 1x SO239 socket with square mount
2. 4x M3x10 ball head screw (for SO239 mount)
3. 5x M3x14 hex head screw (for attaching wires to coils)
4. 4x M3 cap nut (for SO239 mount)
5. 12x M3 washer (for making better contact between wire and coils)
6. 5x M3 wing nut (for attaching wires to coils)
7. Radiator wire (anything you like ~0.7mm diam)