G4AKW

This antenna is a dipole, each leg approximately 60 ft long (overall length ~ 120ft), fed with open wire feeder (ladder line).  Photo 1 shows the ladder line (constructed from plastic garden plant staples garden centre stuff is usually good at withstanding the outdoor conditions!), and the feed point insulator. A short length of 12 guage wire is used to take the wire tension and support the ladderline on each side of the insulator. The ladder line spacing, around 3 inches in this case, and its characteristic impedance, approximately 500 ohms here, is not important. (Spacing determines the maximum power handling capability (volts) and wire thickness (current)). The ladder line enters the house and is connected directly to the transmatch by two lengths of URM 67 coax stripped of its outer sheath and braid (photo 2).  These two 2 ft lengths take the feedline through two 15mm speed fit Polyethylene pipes through the wall and into the living room.  The impedance at the point ...

The photo shows the completed class D 600W 160m and 80m amplifier, mains power supply and antenna change over board. The front pannel connectors provide a connection to the transmit o/c output from the drive transciever (FT817ND, background right). All RF connections and made via the back pannel. The white plastic box houses the slow start circuit from a microwave oven and the rewound oven transformer is on the left. All mains wiring (should be) double insulated. Fuses (a) rear pannel mains input fuse 10A (b) slowstart fuse 10A (c) 24v mosfet fuse 30A.

Antennas are always an issue with neighbours, family, town planners etc. So to date I have limited them to either a) discrete long wire or b) 'TV' like antennas e.g. 2 el band 1 TV antenna for 6metres. However, I had a need for a decent 20m DX antenna and the obvious choice was a vertical. The ideal design was for a full 1/4 wave vertical on the gable end with two 1/4 wave radials sloping down the gable ends. So with the following raw materials: 1) glass fibre fishing pole (7m) 2) 3 x 17ft lengths of 2mm wire 3) Self amalgamating tape 4) 10m UR67 5) 'N' type bulkhead connector 6) chimney brackets and u bolts 7) 2 x dogbone insulators and 2 x standoffs The vertical wire was run up the inside of the fishing pole and soldered to the N type bulkhead. The two radials were then soldered to the N type and the fishing pole shoved over the vertical element. Self amalgamating tape then sealed the bottom and top of the fishing pole. Initially the top section was left off ...