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 in message
...


snip

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.

I needed to abandon my van's fender-mount antenna because the shield ground
broke and AM reception was pretty awful, with spark plug noise and assorted
clicks and pops whenever I wasn't parked.

I got a connector adapter which plugged into the antenna jack on the back of
the radio. I connected a VHF magnetic mount ham radio antenna to it. I now
have a cable running between the bucket seats and out the back door but I
have really good AM/FM reception. On long trips, like across the southern
deserts, I unscrew the standard element and replace it with a longer element
(about 4') and AM reception is improved dramatically. The cable from the
fender-mount antenna dangles inside the dashboard, unseen and unused.

If you think you might tackle such a project, post again and I'll provide
more details. Having a limited knowledge of electronics is not a problem;
finding just the right parts is.

"Sal"

I got a connector adapter which plugged into the antenna jack on the back
of
the radio. I connected a VHF magnetic mount ham radio antenna to it. I
now
have a cable running between the bucket seats and out the back door but I
have really good AM/FM reception. On long trips, like across the southern
deserts, I unscrew the standard element and replace it with a longer
element
(about 4') and AM reception is improved dramatically. The cable from the
fender-mount antenna dangles inside the dashboard, unseen and unused.


I have done the same thing with a spare 2 meter 5/8 whip (without the base
matching coil) on the roof with excellent results. The length is little
longer than stock. I used to own an older European car that had a 3 section
whip that was nearly 5' long fully extended and I wish I could find another.
A 102" CB whip will do better on AM (although less optimal for FM). There
used to be CB/AM/FM splitters for truckers, but I don't know how well they
work. The stock whip is far short considering the wavelength, so the
longest you can get on the car will only improve the capture area. As
mentioned, you will notice a peak if you adjust the trimmer in the radio to
your new antenna. They are usually peaked for 1300 kc anyway, so that might
be something to toy with first if you don't mind sacrificing the high end of
the band. An HF antenna with tuner would be the best you could do. In the
campsite, you can clip a longwire on and throw it in the trees.

I can speak from an experience I had.

I needed better reception on a car radio because I lived in a rural
area. This was years ago but might still apply

I installed a full height 1/4 wave cb whip antenna. I ran the same coax
that came with the original antenna. My radio had a tuning capacitor in
the back of it.

I peaked for maximum signal. Voila, it was much better.

If there is no tuning capacitor in the back of your radio, I suspect
this fix will not work at all.


wrote:
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.

"Michael" ha scritto nel messaggio
. ..
is no tuning capacitor in the back of your radio, I suspect this fix will
not work at all.

Nobody prevent you to add it externally, i think.

BTW... curious to know if any ferrite antenna or 2x ferrite antennas in a
sort of cross-coupled way mounted in a waterproof container perform better
than whips. I goggled, but can't find a gain table for ferrite antennas vs.
dipole, or a medium dBI gain (negative, i suppose) for ferrite antennas
mounted into the commons consumer radios.

Chris, -.-. --.-