FT240-43 Torriod based on the W1JR design
This form of choke is refered to as an Inline-Isolation Balun. Design is quite simple. 70cm of RG-142 high power coax coiled 8 times round a FT240-43 Torroid housed in a waterproof box and potted with Polyester resin. Termination is a chassis-mount SO-239 on opposite ends of the box.
Balun is tested with full UK power limit due to power restrictions, under perfect 1:1 SWR conditions the FT-240 can handle 1KW of power.
In-line Isolation Balun consists of
- 10cm x 10cm x 5cm UV resistant Box
- 1 x FT240-43 Torriod core
- RG-142 high power Teflon Coax or similar
- 2 x SO-239 Chassis Mounted Sockets
- All fixing hardware stainless steel
- Potted for 100% WX proofing
- Feed at lowest band, E.G. 20m