On 15 May 2005 19:37:52 -0700, wrote:

I have a PC FM radio peripheral. It has a standard telescopic steel
aerial that plugs into a base. This works quite well.

However, I would like to recieve some signals that are too weak for
this arangement. I have an external TV yagi, but attaching it either
reduces the recieved signal or increases it only slightly.

Could impedence differences be an issue here? If so, what is the likely
impedence of the yagi and the peripheral?


Yes, chances are that the steel aerial is connected at 75 ohms. Your
yagi is most likely going to be frequency specific unless you are
talking about a log periodic and calling it a yagi.

The standard external TV antenna is a Log Periodic and requires a 300
ohm connection which these days is usually adapted to a 75 ohm coax
via a small balun.

While you may already know this, I will say for clarification to those
who may not...

The Yagi is a beam typically of similar length elements which will
almost look like a rectangle when all the outside tips are connected
by a line. The log periodic will almost look like a triangle in the
same way. Each element considerably smaller and may be pointed
forward to form 'V' shaped elements.


--
73 for now
Buck
N4PGW