VHF Radio Reception on the Thames - Follow Up!

[vandy]

Thank you for all your responses, I have been trying to sort this issue as it is going on my nerves badly!

So I tested the radio, I get 12V voltage at the terminals, both at normal and transmitting mode (whilst trying to transmit).

So disconnected the cable and tested the cable whilst it was connected to the antenna. The tester showed that the cable is short circuited.

Obviousely at the PL259 end (where it is connected to the radio unit) it was completely separated so I knew it must be either within the cable or at the antenna.

So I opened the antenna and as you can see from the attached picture, it was short circuited on purpose by the manufacturer.


So I don't understand this concept really. WHY at the PL259 end we do separate the cable core from sheilds, and at the antenna end they are connected together?!

IS this to provide ground plane?!

 

[Ramage]

It is a method of connecting an unbalanced feeder (Co-ax) to a balanced antenna system.

1/4 wavelength back from a short circuit exists an open circuit (for radio frequencies... obviously not at dc).

It is pretty difficult to describe (and even harder to understand!), but trust me the manufacturer DID do it on purpose!

 

[boatone]

So you still haven't contacted ICOM for advice/guidance, then