On Mon, 19 Jan 2009 13:15:11 -0800 (PST),
wrote:

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).

Daytime coverage map:
http://www.radio-locator.com/cgi-bin/pat?call=KGO&service=AM&status=L&hours=D
2.5, 0.5 and 0.15 mV/m contours. It still should be usable in
Sacramento. Something is wrong.

When you're in Sacramento, have some other driver try their vehicles
AM radio on KGO and see if it's the same. If it's better, it's time
to go shopping for a new radio or a new antenna system on your
vehicle. In particular, try to find a real short wave radio with an
ignition noise blanker, to use for the comparison. Also try it with
the engine off and see if things improve. If all the other radios and
conditions sound roughly the same, give up.

Incidentally, there's usually an adjustable trimmer capacitor to tune
the car antenna somewhere on the radio. It's usually hidden behind
the volume or tuning dial (on older radios with dials) or right on the
front panel on later model radios. Find a weak station and tune for
maximum.

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?

No. Look at the map. You're in fringe-land in the Sierras. The only
way that's going to work is if you get away from local noise sources
(i.e. engines, get a decent antenna, and if propagation is in your
favor). It's possible, but not guaranteed or reliable. Back when I
was getting started in radio, I was a SWL (short wave listener) which
included listening to distant AM broadcast stations. I could hear the
world, but only at random times, not for very long, and certainly not
with armchair listening quality.

Strangely enough, some practice listening to a noisy AM station may
actually improve the quality. I was out of radio for perhaps 15
years. When I dived back in, I couldn't understand anyone on the
radio. It took about a month of listening to "tune" my ear so that I
would mentally ignore the noise and interference. The same thing
happened when I spent 10 years driving back and forth to Smog Angeles
twice a month. I would listen to KSCO on the way. The more I
listened, the better the station sounded.

I do not care if the antenna is
huge/geeky_looking, my car is being driven into the ground anyway.

A big antenna may not help much. It will pickup more signal, but also
more noise. The ratio of the signal to the noise will remain roughly
constant, resulting in no net improvement.

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.

You might look into satellite radio (XM/Sirius). They don't have KGO
but might have equally useful or interesting programming. The nice
part is that it works anywhere.

On the other hand, if you don't need current listening, just have
someone record a days worth of KGO in MP3 format, and play it on a
cheap MP3 player. It may be a day late, but unless you're into the
news, weather, traffic, or sports, it probably doesn't matter being a
day late.

Google Maps
http://maps.google.com/maps?f=q&hl=en&q=37.52639,+-122.10056+(KGO-AM)&om=1

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On Mon, 19 Jan 2009 17:14:27 -0800, Jeff Liebermann
wrote:

Daytime coverage map:
http://www.radio-locator.com/cgi-bin/pat?call=KGO&service=AM&status=L&hours=D
2.5, 0.5 and 0.15 mV/m contours. It still should be usable in
Sacramento. Something is wrong.

Mo
http://www.fcc.gov/fcc-bin/amq?list=0&facid=34471
http://www.fcc.gov/ftp/Bureaus/MB/Databases/AM_DA_patterns/249372-2649.pdf
The antenna pattern is pretty much dead to the east and north-east.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On Jan 19, 7:14*pm, Jeff Liebermann wrote:
Daytime coverage map:
http://www.radio-locator.com/cgi-bin/pat?call=KGO&service=AM&status=L...
2.5, 0.5 and 0.15 mV/m contours. *It still should be usable in
Sacramento. *Something is wrong.

Agree. The link below leads to an example of the noise on a weak,
daytime AM signal received from WBBM, Chicago (50 kW non-D on 780 kHz)
on a Sony ICF-2002 with its internal antenna, indoors in an urban
location. The groundwave path from WBBM to the receiver is about 225
miles in length. According to the FCC propagation curves, WBBM has a
daytime groundwave field intensity of about 0.14 mV/m for this path
(probably less in an urban area).

The noise in this MP3 clip maybe is tolerable for short-term
listening, or if there is nothing better receivable.

The recording was made Jan 10, 2009 at about 12:30 pm CST.

http://www.datafilehost.com/download-18b37f18.html

RF

Richard Fry wrote:
On Jan 19, 7:14 pm, Jeff Liebermann wrote:
Daytime coverage map:
http://www.radio-locator.com/cgi-bin/pat?call=KGO&service=AM&status=L...
2.5, 0.5 and 0.15 mV/m contours. It still should be usable in
Sacramento. Something is wrong.

Agree. The link below leads to an example of the noise on a weak,
daytime AM signal received from WBBM, Chicago (50 kW non-D on 780 kHz)
on a Sony ICF-2002 with its internal antenna, indoors in an urban
location. The groundwave path from WBBM to the receiver is about 225
miles in length. According to the FCC propagation curves, WBBM has a
daytime groundwave field intensity of about 0.14 mV/m for this path
(probably less in an urban area).



In this situation a Select-A-Tenna will work wonders. No good for a car
radio, however.

http://www.old-fashioned-values.com/...ct-a-tenna.htm

On Jan 20, 7:58*am, Dave wrote:
Richard Fry wrote:
On Jan 19, 7:14 pm, Jeff Liebermann wrote:
Daytime coverage map:
http://www.radio-locator.com/cgi-bin/pat?call=KGO&service=AM&status=L...
2.5, 0.5 and 0.15 mV/m contours. *It still should be usable in
Sacramento. *Something is wrong.

Agree. *The link below leads to an example of the noise on a weak,
daytime AM signal received from WBBM, Chicago (50 kW non-D on 780 kHz)
on a Sony ICF-2002 with its internal antenna, indoors in an urban
location. *The groundwave path from WBBM to the receiver is about 225
miles in length. *According to the FCC propagation curves, WBBM has a
daytime groundwave field intensity of about 0.14 mV/m for this path
(probably less in an urban area).

In this situation a Select-A-Tenna will work wonders. *No good for a car
radio, however.

http://www.old-fashioned-values.com/...enna_improve-a...

On a lot of AM auto radios the SN ratio really stinks and an external
preamp especially one with some preselection can really help. As
previously stated on radios with adequate sigal to noise ratio adding
a preamp just makes things worse.


Jimmie

On Jan 20, 11:29*am, JIMMIE wrote:


On a lot of AM auto radios the SN ratio really stinks and an external
preamp especially one with some preselection can really help. As
previously stated on radios with adequate sigal to noise ratio adding
a preamp just makes things worse.

Jimmie

I wouldn't say that. Most all the auto AM radios I've had were
quite good. Always plenty of sensitivity as long as the antenna
was functioning correctly.
The current car I'm driving "Corolla" uses a small helically wound
antenna, which is at the rear of the roof. It's pretty short overall,
and I still have plenty of sensitivity. The daytime is the best time
to check that, and I've never had any trouble receiving out of
town stations. And if I tune to an open frequency, I hear background
atmospheric noise, so any increase in sensitivity is pretty much
useless. I've had older Delco radios in cars and the AM was
excellent on those.
If the OP can hear background noise when tuned to an empty
frequency, and not have it sound "dead", adding more pre-amp
is unlikely to help.
I think the main culprit in this case is propagation, and the
pattern of the array, and unfortunately, I think he's basically
out of luck. Normally you would probably be able to hear the
ground wave out to at least 200-300 miles in the daytime,
but that assumes a fairly stout signal. If the pattern is away
from that direction, even the ground wave possibilities start
to look kind of bleak.
If an auto AM radio does not have enough sensitivity, it usually
means there is something wrong with it, or the antenna.
Most as they come from the factory have more than enough.

wrote:
On Jan 20, 11:29 am, JIMMIE wrote:


The current car I'm driving "Corolla" uses a small helically wound
antenna, which is at the rear of the roof. It's pretty short overall,
and I still have plenty of sensitivity.

Newer cars have active antennas.

Dave wrote:
wrote:
On Jan 20, 11:29 am, JIMMIE wrote:


The current car I'm driving "Corolla" uses a small helically wound
antenna, which is at the rear of the roof. It's pretty short overall,
and I still have plenty of sensitivity.

Newer cars have active antennas.

The helical on some antennas is for wind noise.

On Jan 20, 8:30*pm, Dave wrote:
wrote:
On Jan 20, 11:29 am, JIMMIE wrote:

The current car I'm driving "Corolla" uses a small helically wound
antenna, which is at the rear of the roof. It's pretty short overall,
and I still have plenty of sensitivity.

Newer cars have active antennas.

I don't think mine is, but I'm not sure. It's basically the
same setup as any other antenna, just the whip is
shorter, and helically wound, I suppose for tuning purposes.
I guess it's about 15 or so inches long. I'd have to measure
it. Of course, it also functions for FM too.