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Old January 19th 09, 09:44 PM posted to rec.radio.amateur.antenna
christofire christofire is offline
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First recorded activity by RadioBanter: Oct 2008
Posts: 173
Default improve S/N for AM car radio by a factor of 2...5...10?


wrote in message
...
Hi all,

I've looked on the web, but with very little success. I have never
posted to this group before, so I apologize if my question is lame.

I listen to the Bay Area's KGO 810 MHz a lot. Their transmitter is
located in South San Fran Bay near the Dumbarton Bridge, and outpus 50
kW (that's what they say anyway). I am guessing, it's directed mostly
at the Pacific coast line. I often listen while driving east on I-80
to Truckee/Tahoe for skiing and camping. Usually the signal fades
substantially by the time I reach Sacramento - but it's still
tolerable listening (by ear, S/N of ~3). By the time I reach Auburn
it's essentially inaudible. Much better signal at night (~again, by
ear, S/N improves by ~2). At night, I can sort of pick up words in
truckee.

Question: can I *substantially* improve the S/N - say, factor of
2/5/10 by installing a better car antenna, so that, say, I could
listen in the Sierras day and night? I do not care if the antenna is
huge/geeky_looking, my car is being driven into the ground anyway. I
would be happy to make this a DIY project - to save on $ and learn
about radio. What kind of specs should I look for? I.e. I don't want
to go on the web and blindly buy an antenna advertised to "boost" your
AM radio reception - I would want some numbers.

I have limited knowledge in electronics, my background mostly is in
biophysics and biochemistry. So if you steer me into the right
direction I think I should be able figure it out.



Presumably you mean 810 kHz. What is the source of the noise? Noise
generated in the receiver is usually insignificant in the medium-wave band.
If the cause is other transmissions on the same and nearby frequencies you
may not gain much by changing the antenna, but a receiver with better
channel (IF) filtering may help if there is any contribution from adjacent
channels. If the noise is coming from your car (does it improve when you
park in a rural area) then you may need to improve the RF suppression of its
circuitry (e.g. ignition if it's a petrol engined car).

I expect you can work out what tests would be needed to locate the principal
sources of the noise.

Chris