Wow Bob, that was some reply. Very much appreciated.

-... but be aware that the length of coax will
also receive in its own right if both the radio and antenna ends arent
terminated in its surge impedence (ie 75 ohms).

Couldn't quite understand that (word ot two missing?)


I assume you mounted a dipole at the top
of it?

Nope, the top end is just sitting on the floor of the loft, the
surplus coiled up. Last night I did get a reasonably clean signal from
Radio 3 in stereo so we're not looking at a need for massive gains.

- If patience was in huge supply I'd try matching at the receiver input
for a 75 ohm cable. I'd go inside the radio to do this.

Would this need a transformer, inductance/capacitance circuit, static
resistor, or what??

Bob, could you explain one mystery to me? A normal aerial arrangement,
whether fed by ribbon or coax, is effectively one continuous loop of
wire. DC resistance is at most a few ohms - ie pretty much a dead
short. Impedence is resistance to AC, ie the signal, but the fact that
impedence is present doesn't remove the dead short. So how come
anything gets around the loop at all?!!

Or is it that the entire loop can be seen as one side of a circuit for
which it provides a potential difference?

And another: Where does this PD occur? Across the receiving element of
the aerial, or within the element relative to earth? Does this mean an
aerial 'loop" works differently from a single long wire?

You probably see what I'm getting at.

Thanks again
Paul


On Tue, 15 Mar 2005 05:36:34 +1100, Bob Bob
wrote:

Hi Paul

Yes it looks like you have a real problem here..