Dave Plowman (News) wrote:
In article ,
Mark Carver wrote:

It's really of no relevance. The characteristic impedance of the aerial
itself will not be 300 ohms , IIRC that's the impedance of a folded
dipole ? and how many of those do you see on a car ? !


There's mismatches everywhere, not least because the aerial is usually
just a length of conductor, you'd need to apply chaos theory mathematics
to calculate them, however essentially a car radio takes an unbalanced
input so just use any RF grade co-ax that mechanically fits the bill.


This will work for VHF, but not AM. Modern radios have automatic matching
for AM - older ones had a preset. When extending an aerial lead you use a
pukka extension which is matched already by IIRC the addition of series
capacitance.

There used to be a tiny trimming capacitor normally on the front panel
for this matching. On modern sets I don't know how this is achieved
automatically ?

troll mode

Who bothers to listen on crappy old AM these days anyway ?

/troll mode

--
Mark
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