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Author: Subject: Car Aerial Impedance?
SALAD

posted on 13/5/13 at 08:59 PM Reply With Quote
Car Aerial Impedance?

My brain is starting to hurt now so I'll ask on here.....Can you power a standard FM car aerial using something like this:

AIV CAR RADIO ANTENNA ADAPTER ISO TO AUDI/SEAT/VW 50 Ohm 10 cm BRAND NEW | eBay

Would such adapter reduce the FM aerial's impedance of 75ohm to 50ohm?

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HowardB

posted on 13/5/13 at 09:03 PM Reply With Quote
not sure what the device does,. AIV?

but never the less for reception purposes impedance of 50 or 75 ohms is almost academic. Only for transmission need it be a significant issue unless the signals are very marginal.

not sure that answers the question, but as I say for reception the impedance mismatch is not an issue.

hth







Howard

Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)

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spiderman

posted on 14/5/13 at 01:23 AM Reply With Quote
50 ohm for radio transmission/reception 75 ohm for video so should be okay. The adapter is for an antenna with a signal amp incorporated in it to connect to a non manufacturers radio. First test would always be to make sure earths are all good, a majority of problems are earth related.

Hope that helps
Spider.





Spider

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ChrisW

posted on 14/5/13 at 02:32 PM Reply With Quote
Also keep in mind that so-called 'amplifiers' for radio reception will not improve reception where poor signal is a problem. The exception here is a distribution amplifier to enable multiple devices to use the same aerial.

The reason for this is that what we consider the 'signal level' is actually the difference of the signal level above the background noise aka 'signal to noise ratio'. An amplifier cannot determine the difference between signal and noise, it amplifies everything, and as such the ratio never changes and the perceived signal level never improves. In fact, the amplifier itself adds noise so in fact you will be worse off than when you started.

Think of it like this: If a person talks at the same level as the noise coming from a radio you will struggle to hear them. If you double the volume of each, the person is still masked by the noise of the radio.

The key to good radio (or TV, or anything) reception is to get the aerial right. No amount of compensation further down the line if the underlying problem is a lack of received signal.

Chris





My gaff my rules

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SALAD

posted on 15/5/13 at 05:34 PM Reply With Quote
Thanks for the replies guys.
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