Boosting AM - Still Done The Same Old Way?

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Muskmelon
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Boosting AM - Still Done The Same Old Way?

Post by Muskmelon » Fri Feb 25, 2005 11:39 am

There is an AM radio station about 70-to-90
miles from my home. Its between thirteen
and fourteen hundred KHz. I didn't think I
would live long enough to ever care about
anything broadcast on AM. I remember
listening to AM when I was a preteen.<p>My parents let me purchase a booster from
Edmund Scientific called the Select-A-Tenna.
Incredibly, I recently saw an ad for the same
gizmo on page 52 of the Feburary 2005 edition
of Nuts & Volts. It did boost the AM signal,
but when I added about 100 feet of 300 ohm
antenna wire to the thing I was able to pick
up stations as much as 1500 miles from where
we lived. As a boy, it seemed like a genuine
miracle!<p>The station I want to hear can be received if
I drive about ten to fifteen miles from my home.
I'm driving parallel to the station. In other
words, I'm about the same distance. The strange
thing is this area that I drive to about once
a month is loaded with concrete and steal build-
ings. My home is in a suburb with all one and
two story homes. <p>I've got a few old schematics that use one IC,
a few ceramic capacitors and resistors. They
all require a "long wire" type of antenna. The
idea of stringing a hundred feet of wire around
one of my bedrooms doesn't exactly fill my heart
with joy! I tried an AM/FM booster sold by
Radio Shack. If there was a change in the
strength of the AM signal, it must have been
so slight that is was not detectable. <p>I've got a GE SuperRadio, which has a good size
ferrite rod style AM antenna, yet I can't hear
anything when I tune to the station I want to
receive. Are there any schematics for AM
boosters that work, and don't require long
lengths of wire?<p>Muskmelon

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jollyrgr
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Re: Boosting AM - Still Done The Same Old Way?

Post by jollyrgr » Fri Feb 25, 2005 4:25 pm

As a kid I was very skeptical of the ads for the Select-A-Tenna. How could something boost a radio signal WITHOUT batteries and WITHOUT wires? I didn't believe it. Even as an adult I didn't believe these would work worth a darn. Then a friend got the Radio Shack equivalent and told me how well it worked. And these do work without wires or without a power source.<p>The Select-A-Tenna type thing is your best bet. These are typically referred to as AM LOOP ANTENNAS. Radio Shack had one that they discontinued. But I managed to pick one up off eBay and another at a ham fest. I've got less than $20 invested in these and the work better than expected. There is only one radio that baffles me as to why the AM loop does not work with it. All others from Baygen Freeplays, Shortwave digital radios, and even "freebie" AM nine volt battery radios work great. Since RS does not sell this anymore and the ones from CCrane are so expensive, I suggest checking out eBay.<p>For those not familiar with the AM LOOP antenna, let me explain. It is a loop of wire in parallel with a tuning capacitor that forms a resonant antenna. You simply place the coil next to the AM radio, no wires needed, and tune the radio to the desired frequency. Sometimes you cannot hear the station at all so you get the tuner in the ballpark. Next you tune the antenna by rotating the capacitor until you hear an increase in signal strength. There have been many times where I can't even hear a station and put the antenna next to the radio. After some tweaking I get a signal that is better than the local "clear channels". Mostly I find I need the loop antenna at night.
No trees were harmed in the creation of this message. But billions of electrons, photons, and electromagnetic waves were terribly inconvenienced!

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Edd
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Re: Boosting AM - Still Done The Same Old Way?

Post by Edd » Fri Feb 25, 2005 11:46 pm

Looking into my circuit construction archives I found this and thought that this might be of interest on that topic of AM loop antennas and constructing of same. Being of passive design, but seems like I also have one with a FET or xstr post amp, but it must be in other of my files.
Hopefully you would use the second floor height advantage as well as the improved reception propagation of night time . Seems any distant station might be a challenge if it was attempted in daytime. Take particular notice of the gain consideration by increasing loop size .
See:
http://www.mindspring.com/~loop_antenna<p>Your reception enhancement in the auto might also be attributable to the enhanced design parameters of a mobile receiver having to perform with only the use of a short vert rod antenna.
However, some auto receivers in the immediate past (80’s) were minimizing the AM receiver design complexity as an imposed afterthought with impaired performance of their weaker reception. However in the last 3 years or so I have seen some CXA series of Sony radio all in one chips that do not skimp in their AM section performance at all.
I think I understood your reference to the fact of the 15 miles, not being closer 15 miles, but being in the same rotary azimuth 15 mile distance as you would have been at your home. If there is a chance that the station is an old timer and used dual towers possibly that might account for it, in the respect of the radiation pattern not being a circle but deviating towards an oval or figure 8 pattern in their signal strength coverage.
Any chance of giving the stations call letters and your receive location for further research as well as listening time(s)?<p>73's de Edd
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Re: Boosting AM - Still Done The Same Old Way?

Post by Dean Huster » Sat Feb 26, 2005 10:01 am

I have a write-up on AM broadcast band DXing that I'll post on this thread if there's any interest. A tube-type AM car radio of the early 1960s has some of the best receiver circuitry around as many of them have a tuned RF amplifier in addition to at least two IF amplifiers. No, they aren't digital, but then, as Edd mentioned, modern car radios add the am broadcast band only as an afterthought, not caring about performance at all.<p>Adding a long-wire antenna can be easier than you think. Yeah, a wire run around a room is ugly and has limits on length. A lot of folks run it around in several directions and although may provide some degree of omnidirectionality, can tend to cancel some signal as well. One of my solutions was to run an antenna at the peak of the house in the attic. It's out of the weather, it's pretty long and easy to drop a feed-line down to the room in question, minimizing any wall damage.<p>Adding a preamp to a radio doesn't always give the best results as it only amplifies what the antenna picks up, noise and all. The better the antenna, the better the signal. The loop antennas not only provide a directional capability to improve the signal strength of the target station, but it also minimizes signals from other stations to reduce same-frequency interference.<p>Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

Muskmelon
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Re: Boosting AM - Still Done The Same Old Way?

Post by Muskmelon » Sat Feb 26, 2005 12:12 pm

I apologize for not getting back to the Nuts &
Volts Forum sooner. I'm in the middle of network-
ing several PCs. As you might imagine, the
problems are considerable.

WOW! I'm very impressed with all your replies.
I can't thank you enough Jolly Roger, Edd Whatley,
and Dean Huster. <p>If I can find the Select-A-Tenna at a reasonable
price I guess I'll give it a try. It worked
great when I was kid, but there were a lot
fewer tall buildings made of concrete and steel.<p>Edd Whatley mentioned that it would be helpful
if I gave the station call letters and my
approximate location. I'll tell you Edd, it
wasn't easy describing the problem I was having
while deliberately avoiding the name and location
of this AM station.<p>When I was a kid we could receive five or six
VHF stations and a few UHF. Each AM and FM radio
station seemed to strive for uniqueness. Now,
when I turn on one of a zillion cable channels
or listen to the radio I almost feel physically
sick. I don't care about the lives of hollywood
celebrities and the flood of far right radio
and TV programs makes me feel like an alien in
my own country.<p>I heard about a station that started up a year
or two ago. The investors said they wanted to
finance an all talk station that would strive
to provide a balanced look at politics, religion,
etc. That's exactly what they did.<p>I've learned to keep my opinions to myself over
the years, as the nation turned away from
moderation and reason, in favor of ultra right
wing politics and religion.<p>Now you know why I avoided giving the call letters
of the station. I actually fear for the physical
safety of the hosts at this station. They are
defintely voices crying out in the wilderness.
Chances are they won't be around much longer.<p>Muskmelon

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Joseph
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Re: Boosting AM - Still Done The Same Old Way?

Post by Joseph » Sun Feb 27, 2005 6:56 pm

I used to notice how holding a portable radio next to a water pipe used to boost reception greatly. Maybe you can make use of that principle somehow. I can sympathize with you about right wing programming.

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Re: Boosting AM - Still Done The Same Old Way?

Post by peter-f » Tue Mar 01, 2005 10:46 am

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Dean Huster:
....<p>Adding a long-wire antenna can be easier than you think. Yeah, a wire run around a room is ugly and has limits on length. A lot of folks run it around in several directions and although may provide some degree of omnidirectionality, can tend to cancel some signal as well. One of my solutions was to run an antenna at the peak of the house in the attic. It's out of the weather, it's pretty long and easy to drop a feed-line down to the room in question, minimizing any wall damage.<p>Dean<hr></blockquote><p>My father's old setup was for AM and short-wave reception.... he used a WWII vintage- RCA AR-88 as receiver.
For his antenna, he ran a wire up (2 floors to the attic) and around the attic space... Lucky to have an unused, unfinished, accessable attic.<p>Look into antenna design and tuning... many 1960's era Amateur Radio handbooks will show what you need to do. The length and orientation of the antenna may play into just what frequencies are easily tuned or not.<p>As for better reception at different location and same distance... that's (probably) wave theory at work... Using 2 or more towers, you can focus the direction and intensity of the radio wave... along the east coast or Mississippi valley, it's common to direct the beam north-south... along the Great Lakes, it would be east-west - more people (= audience) along those general directions.

Dean Huster
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Re: Boosting AM - Still Done The Same Old Way?

Post by Dean Huster » Tue Mar 01, 2005 5:17 pm

I believe that it was in a 1960s era issue of Electronics Illustrated that Tom Kneitel published an article describing how to build a two-antenna setup, one a horizontal long-wire and the other a vertical long-wire, to be used to determine if a station was transmitting from where they claimed they were transmitting, an especially hot item with clandestine/pirate broadcasters.<p>Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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Edd
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Re: Boosting AM - Still Done The Same Old Way?

Post by Edd » Tue Mar 01, 2005 7:05 pm

“Edd Whatley mentioned that it would be helpful if I gave the station call letters and my approximate location. I'll tell you Edd, it asn't easy describing the problem I was having while deliberately avoiding the name and location of this AM station.”<p>Au contraire, messr…I was merely thinking along the line of finding the info on the AM station in respect to its power allocation and if it has to cede to lower power operation after 6 PM, as well as consulting a topographical map as per terrain considerations on its propogation/coverage.
Since you have piqued the consideration of station ID, I might consider it to be WLIB at 1360 in NOO YORK CITEE, or on the far coast KSDL at 1190…(too low)…in San Diego. Or other like associates of the Air America affiliation.<p>Dean:
At times I also do AM BCB DX and my best location ID procedure is using a receiver that initially had a ferri-loop antenna for pickup. The normal size was the longest 7 in length by ⅜ in diameter unit….however….. I had approximately 1k surplus round pot cores of the proper μ for that frequency and strung 24 of them together with an end threaded nylon rod thru their center holes and nylon nuts on the ends with inter core fusion provided by alpha cyanoacrylate. A closewound linear coil on a cardboard bobbin using Litz wire yielded an 160uh value which could be further adjusted for final tracking by sliding it within ½ of the end of the new ferrite core, now being a quite respectable 1⅛ in diameter by 18 in length. Xmitter location was not accomplished by the peak signal indication, but instead, by the 90° offset null of the loop , it being ascertained either by acoustics or AVC voltage monitoring. A lightweight 24 in sheet metal plate held up 6 in from either rod end would establish between the end of the loop towards the station if that was ever in question.(Typically East-West, as I certainly could ascertain between Canada-Mexico or the ocean)<p>73’s de Edd
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;) ;) <p>To err is human, to forgive - highly unlikely.<p>[ March 01, 2005: Message edited by: Edd Whatley ]</p>

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haklesup
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Re: Boosting AM - Still Done The Same Old Way?

Post by haklesup » Tue Mar 01, 2005 11:11 pm

Does this station broadcast on the internet? Maybe you could "talk" them into it. Call during a show and rally some listener support. Do they at least have a website?<p>(Questions are rhetorical since I know you prefer to keep the station anonymous)

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Re: Boosting AM - Still Done The Same Old Way?

Post by Bob Haller » Wed Mar 02, 2005 6:40 am

Some stations use directional antennas to avoid interfering with neighboring stations,and radio waves can and do bounce of hills and buildings.<p>this may explain your getting the station in another area. try calling the station they always want more listners and will be happy to speak with you.<p>many years ago a buddy ran a bootleg station on the AM band using the call sign of a detroit station. were in pittsburgh but happened to drive by the detroit station so on a trip we stopped to take a picture. they gave us a tour of the station, coffe mugs, let us take all the pictures we wanted including engineering. my friend has a electronics degree, lots of shop talk. they were impressed we heard them in pittsburgh little did they know the real reason :)

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sofaspud
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Re: Boosting AM - Still Done The Same Old Way?

Post by sofaspud » Thu Mar 03, 2005 3:32 pm

A few days ago I was flipping through my old copies of Electronics Handbook magazine. I saw a Homer Davidson project for an AM booster that is built into a plastic box and positioned alongside the radio's AM antenna (similar to an active version of the concept that Joseph mentioned). Reply if interested.

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Re: Boosting AM - Still Done The Same Old Way?

Post by Yerry » Thu Mar 03, 2005 5:58 pm

IIRC, a Nat'l Radio Club review of the then-new GE SupeRadio II mentioned that a Select-A-tenna did very little for the radio. It went into further detail in that the SAT worked best (and quite well) with radios having poor front ends. The SAT worked equally poorly with other high-quality radios.

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Re: Boosting AM - Still Done The Same Old Way?

Post by George Cooper » Mon Mar 07, 2005 5:33 am

I should have posted this when the topic first came up. All Electronics Corp sells an AM/FM antenna made by Terk for Philips/Magnavox. It is 5.9" x 5.7" x 1" The price is $6.95 with shipping andhandling being $6 . I just bought one but have not tried it yet. See the web site for details.
I remember an AM antenna design that was two 7" ferrite rods that were glued together on the ends and wire being rewound aound the antenna. The late Joe Carr had a book on receiving antennas with several AM designs. None I believe involving a long wire. Although there was one that involved ribbon cable and an embroidery Hoop.
Most of your best AM Reception will happen after dark. I can easily pick up New York, Chicago, and Boston from here in Cleveland with the average radio. To which I will add my own strange radio reception story. In the mid 1980's I was riding on a Gayhound Bus running from from Cleveland to Baltimore. It was about 11:30 PM at night and we were going down hill from the sound of the motor. On a little Panasonic AM/FM "brick" I picked up a nationally sindicated talk show out of Des Moine, Iowa. Now that is reception!
George

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Re: Boosting AM - Still Done The Same Old Way?

Post by Bernius1 » Tue Mar 08, 2005 5:49 am

I couldn't resist....
My brother had a Realistic 75W receiver, flywheel 6-gang tuner, in the 80's. He ran 18ga bell wire in the eaves as a 40' dipole. From LI, NY ( or as some gals say ' Lawnk Eye-lunt' ), Baltimore stations came in full stereo. Nice.
Can't we end all posts with a comical quip?

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