Science Fair Project
 

i'm working on a science fair project. i'm building an am-radio
transmitter. i can only be a few inches from the receiver. how do i
solve this problem without making my antenna enormous.

Science Fair Project
 

On 6 Feb 2007 20:55:20 -0800, "T" wrote:

i'm working on a science fair project. i'm building an am-radio
transmitter. i can only be a few inches from the receiver. how do i
solve this problem without making my antenna enormous.

Build a loop stick antenna (Google the term).

73's
Richard Clark, KB7QHC

Science Fair Project
 

Or use fine wire to build a larger multi-turn loop antenna into the
perimeter of the "story-board" for your science fair display. If this is
truly a science fair project, then the antenna is an important part of the
story that should be shown, isn't it?

Joe
W3JDR


"Richard Clark" wrote in message
...
On 6 Feb 2007 20:55:20 -0800, "T" wrote:

i'm working on a science fair project. i'm building an am-radio
transmitter. i can only be a few inches from the receiver. how do i
solve this problem without making my antenna enormous.

Build a loop stick antenna (Google the term).

73's
Richard Clark, KB7QHC

Science Fair Project
 

will this boost my transmitter's signal, or the reciever's antenna?

Science Fair Project
 

On 7 Feb 2007 18:45:29 -0800, T posted in total:

will this boost my transmitter's signal, or the reciever's antenna?


Will _what_ boost _what_ transmitter's 'signal'????

What is a "reciever"?

Oh, I see:
Message-ID: . com

Science Fair Project
 

On Feb 7, 6:45 pm, "T" wrote:
will this boost my transmitter's signal, or the reciever's antenna?

Um, if you connect the better antenna to the transmitter, how would
that affect the receiver? If you connect the better antenna to the
receiver, how would that affect the transmitter? Clear?

Cheers,
Tom

Science Fair Project
 

On 6 Feb, 20:55, "T" wrote:
i'm working on a science fair project. i'm building an am-radio
transmitter. i can only be a few inches from the receiver. how do i
solve this problem without making my antenna enormous.

If you build an amplifier at the initial recerving antenna which is
preferably
outside the house the signal within the coax leading to and within
the house
will be strong enought to overcome the losses entailed by using a
long
connecting coax. Placing the amplifier at the antenna prevents noise
from
overpowering the incomming signal The amplifier need only to be a
simple
transister driven by a battery. Remember that the signal to noise
ratio will
never be better than the signal recieved by your antenna before
amplification
which should provide the impetus to build the best antenna you can
build
and situated in the most desirable place for receiving..
Good luck
Art

Science Fair Project
 

On Feb 8, 8:07 pm, "art" wrote:
On 6 Feb, 20:55, "T" wrote:

i'm working on a science fair project. i'm building an am-radio
transmitter. i can only be a few inches from the receiver. how do i
solve this problem without making my antenna enormous.

Placing the amplifier at the antenna prevents noise
from
overpowering the incomming signal The amplifier need only to be a
simpleIf you build an amplifier at the initial recerving antenna which is
preferably
outside the house the signal within the coax leading to and within
the house
will be strong enought to overcome the losses entailed by using a
long
connecting coax.


I think he means the AM broadcast band.. Or I assume anyway.
The loss with most any length of coax at that MW freq should be
dinky indeed.
I built one of those when I was about in 7th grade. Mine had like
a small tight wound loop for an antenna if I remember right. But I
might
have even tried hooking it to to my then SWL antenna which was a 50
ft random wire. I don't know how critical the transister? is as far as
match. If it's not picky, you could probably just string out a short
wire. There are probably FCC antenna standards as far as such a
device,
but I'm too lazy to look them up.. I don't think the FCC wants them
radiating too far. As far as receiving at MW, Any commercial radio
should be good enough with whatever antenna came with it.
Well, unless it's a really lousy radio.. :( If you can hear noise
in between stations in the daytime, it's good enough and can't really
be
improved too much as far as s/n ratio.
MK

Science Fair Project
 

On Feb 7, 9:18 pm, Nobody wrote:
On 7 Feb 2007 18:45:29 -0800, T posted in total:

will this boost my transmitter's signal, or the reciever's antenna?

Will _what_ boost _what_ transmitter's 'signal'????

What is a "reciever"?


ok. let me be more clear. my transmitter is a simple am-radio
transmitter. it is essentially an aduio transformer connected to a
1mhz crystal oscillator. i have, connected to my oscillator's antenna
lead, a simple telescoping radio antenna, and so my "transmitter"----
[the am-radio transmitter] has to be just a few inches from my
"reciever" ----[the am-radio] for the "reciever" to pick up my
signal.

My question is: will this antenna, the loop stick antenna mentioned
above, boost the signal coming from my "transmitter" or will it just
allow my reciever to pick up the signal easier? or in other words how
will this antenna help me?

sorry if i wasn't clear enough before. i just thought you would
understand what i was talking about.

Science Fair Project
 

On 8 Feb 2007 20:12:15 -0800, "T" wrote:

My question is: will this antenna, the loop stick antenna mentioned
above, boost the signal coming from my "transmitter" or will it just
allow my reciever to pick up the signal easier? or in other words how
will this antenna help me?

No one can tell how anything can help if you don't tell us what help
you need.

Being able to receive inches away speaks to an accomplishment, not a
problem. If you want to receive miles away, then the comparison
between what is accomplished and what is desired reveals the problem.

sorry if i wasn't clear enough before. i just thought you would
understand what i was talking about.

You never really "talked about" anything when the sum total of your
correspondence barely exceeds a half dozen lines up to this posting.

Now, we can all presume an intent, and that intent goes counter to
what is allowed by law, and that is long distance communication on
commercial frequencies by an unlicensed station. The law is
exceptionally clear as to how much power is allowed, into how large a
radiator, for unlicensed stations (such as yours). The long and short
of it is that without exceptionally good reception gear, that distance
is rarely more than across the room, or within a block.

Clearly, even these distances vastly exceed your current
accomplishment of a few inches because you could invest little more
effort into doing it with a modulated LED across the room. TV remotes
do this a billion times an hour world-wide.

Even with the allowed sized radiator, it is pathetically inefficient
(which is the intent of the law). The name of the game is called
matching, and a XTAL oscillator is a poor power source.

However, all of this is strictly window dressing unless the whole
scope of your Science Fair project is limited to building a working
transmitter. If so, you need to formulate better questions. If not,
you are spending too much time when you could build a Ramsey Kit in an
afternoon and get on with the grist of the project.

73's
Richard Clark, KB7QHC

Science Fair Project
 

All i want is to be able to pick up the signal from my "transmitter"
with an am-radio across the room.

Science Fair Project
 

T wrote:
All i want is to be able to pick up the signal from my "transmitter"
with an am-radio across the room.


Hold on guys! T, this is a rarified group here, and sometimes it shows.


Okay, so you have a transmitter that is presumably transmitting somewhere.

You want to be able to receive the signals on an AM radio at some
distance. Let's collect a little data, and I maybe I can help.


If you are using a typical AM radio to pick up the signals, you don't
need to do anything with it. It's already got an antenna.

Now on to your transmitter.

If the transmitter is working, you should be able to pick up a pretty
strong signal when the receiver is sitting next to it. Even if you just
have a short piece of wire on the transmitter.

If you don't, it is possible that the transmitter is not working. It is
also possible that if you have only a weak signal, you might be
transmitting on a "harmonic" frequency. This is pretty much double or
half, but it means that you are getting a much less powerful signal to
the radio.

Assuming that your transmitter can be tuned, set the radio at some
frequency, preferably on the lower part of the band and away from local
stations.

Now, with the radio sitting right beside the transmitter, tune the
tansmitter until you hear the signal you are looking for. Even when you
get a signal, you might try tuning the transmitter all between it's
limits just in case a harmonic signal is what you found at first. Go
with the strongest signal.

Now start moving the radio away from the transmitter. At some point,
the signal will become weaker, eventually going away - and if it
doesn't, your doing great.

If not, you need to lengthen the wire. There are some legal limits to
this, and I think that they are around 5 feet or so. Someone else might
be able to chime in here if they know exactly.

Some misc stuff:

The transmitter circuit may change frequency as you move toward or away
from it. Putting metal between you and the circuit can help, although
with some adjustment, you can predict how much change there will be and
accommodate the problem.

If you aren't getting anything with a short wire antenna and the radio
right beside the transmitter, the transmitter probably isn't working.

- 73 de Mike KB3EIA -

Science Fair Project
 

Richard,

Please try to tone down the magniloquence a little. Just explain why
you suggested a loopstick antenna in plain English. Obviously the man
is not a radio engineer (or whatever) of your caliber. You can save
the 'waxing eloquent' for the newsgroup regulars.

thanks,
jk

Richard Clark wrote:
On 8 Feb 2007 20:12:15 -0800, "T" wrote:


My question is: will this antenna, the loop stick antenna mentioned
above, boost the signal coming from my "transmitter" or will it just
allow my reciever to pick up the signal easier? or in other words how
will this antenna help me?


No one can tell how anything can help if you don't tell us what help
you need.

Being able to receive inches away speaks to an accomplishment, not a
problem. If you want to receive miles away, then the comparison
between what is accomplished and what is desired reveals the problem.


sorry if i wasn't clear enough before. i just thought you would
understand what i was talking about.


You never really "talked about" anything when the sum total of your
correspondence barely exceeds a half dozen lines up to this posting.

Now, we can all presume an intent, and that intent goes counter to
what is allowed by law, and that is long distance communication on
commercial frequencies by an unlicensed station. The law is
exceptionally clear as to how much power is allowed, into how large a
radiator, for unlicensed stations (such as yours). The long and short
of it is that without exceptionally good reception gear, that distance
is rarely more than across the room, or within a block.

Clearly, even these distances vastly exceed your current
accomplishment of a few inches because you could invest little more
effort into doing it with a modulated LED across the room. TV remotes
do this a billion times an hour world-wide.

Even with the allowed sized radiator, it is pathetically inefficient
(which is the intent of the law). The name of the game is called
matching, and a XTAL oscillator is a poor power source.

However, all of this is strictly window dressing unless the whole
scope of your Science Fair project is limited to building a working
transmitter. If so, you need to formulate better questions. If not,
you are spending too much time when you could build a Ramsey Kit in an
afternoon and get on with the grist of the project.

73's
Richard Clark, KB7QHC

Science Fair Project
 

thanks mr. coslo, that was very helpful.

i'm sorry to keep bothering you all, but is there any other kind of
antenna that i can legally build that will allow me to transmit my
signal across the room, or is a simple piece of wire my best bet? see,
i don't know a whole lot about antenna construction, so what i mean is
will another type of antenna, such as the loop stick antenna, give me
better rececption across the room?

does anyone know of any website(s) where i can learn the construction
and uses of differnt types of antennas?

Science Fair Project
 

On Fri, 09 Feb 2007 12:17:48 -0800, Jim Kelley
wrote:
Just explain why you suggested a loopstick antenna in plain English.

Hi Jim,

You are complaining for complaining's sake when it is bereft of
advice. Explanation is not being sought, solutions are.

Obviously the man is not a radio engineer (or whatever) of your caliber.

You are being overgenerous - of any caliber - and why should he/she
be? This mocks the complaint for advice that would require some
engineering talent. Our student wants to be heard across the room.
There have been a sufficient number of solutions to achieve that,
certainly. All that's left is the doing.

73's
Richard Clark, KB7QHC

Science Fair Project
 

Richard Clark wrote:
Hi Jim,

Hi

You are complaining for complaining's sake when it is bereft of
advice. Explanation is not being sought, solutions are.

Apparently both are being sought. That is usually the nature of
follow-up questions.

You are being overgenerous - of any caliber - and why should he/she
be?

It's certainly not something of which you might frequently be acused.

This mocks the complaint for advice that would require some
engineering talent. Our student wants to be heard across the room.
There have been a sufficient number of solutions to achieve that,
certainly. All that's left is the doing.

Thank you for your magniloquence.

The word applies beautifully, don't you agree? :-)

I can certainly imagine why you suggested a loopstick for the
transmitter. We can only hope that your unfortunate correspondent
continues trying to imagine it long enough to happen upon the reason.

73, ac6xg

Science Fair Project
 

T wrote:
All i want is to be able to pick up the signal from my "transmitter"
with an am-radio across the room.


Ok. I have been watching the discussion on this thread for a while now.
Some people have attempted to help, others just wasted band width.

The situation is that you want to do a demonstration that involves
transmitting a signal and receiving it.

FCC part 15 regulations specify that a low power am transmitter can not
exceed a very low power level ( I don't remember off hand how much) and
the antenna must be attached to the transmitter and must not exceed
about 5 or 6 feet.

Any am transmitter that meets these limitations will function in the
manner you desire to exhibit. Any am receiver will detect the signal
from the transmitter over a distance of 50 to several hundred feet.
There are many suppliers of these devices.

Just do a Google search for "Part 15 Transmitters" and you will find
more than you can use. Siple receivers can be obtained from similar sources.

I do not know what you intend to do but don't concern your self to much
on finding the electronic equipment you need, it is readly available and
fairly inexpensive.

Good Luck

David Nagel
WD9BDZ

Science Fair Project
 

Thank you mr. kelly for trying to help me out, but obviously richard
is too hostile to want someone else, even a kid, to learn anything
about radio engineering. [you know, since he probably never tinkered
with electronics when he was a kid and asked someone for advice] =
sarcasm

i'm slightly disappointed in him. a grown man, who attacks eager to
learn children over the internet. do you not have friends? a life?

besides if you don't help people, but instead show them hostility,
don't you think they may become discouraged? maybe even give it up and
quit? if there is no one interested in this type of engineering, then
it may cease to exist.

all i'm saying is, be an encourager, help others, and go with god.

"since new developments are the products of a creative mind, we must
therefore stimulate and ENCOURAGE that type of mind in every way
possible." -george washington carver

sorry to be so short, and thanks to everyone who tried to help,
taylor

Science Fair Project
 

"T" wrote in message
oups.com...
Thank you mr. kelly for trying to help me out, but obviously richard
is too hostile to want someone else, even a kid, to learn anything
about radio engineering. [you know, since he probably never tinkered
with electronics when he was a kid and asked someone for advice] =
sarcasm

i'm slightly disappointed in him. a grown man, who attacks eager to
learn children over the internet. do you not have friends? a life?

besides if you don't help people, but instead show them hostility,
don't you think they may become discouraged? maybe even give it up and
quit? if there is no one interested in this type of engineering, then
it may cease to exist.

all i'm saying is, be an encourager, help others, and go with god.

"since new developments are the products of a creative mind, we must
therefore stimulate and ENCOURAGE that type of mind in every way
possible." -george washington carver

sorry to be so short, and thanks to everyone who tried to help,
taylor

Hi taylor

Did you google loop stick antenna?

Jerry

Science Fair Project
 

Taylor wrote:
"I`m working on a science fair project. I`m building an am-radio
transmitter. I can only be a few inches from the receiver. --------"

The information is sparse but may be enough.

Kits are available for low-powered transmitters which are restricted by
law to a short wire antenna to avoid harmful interference.

My experience is that this is adequate. The receiving antenna is almost
unrestricted. It may extend to closely couple with the transmitting
antenna, though this is rarely required.

Most receivers are capable of receiving a very weak signal which means
the receiving antenna can be distant from the transmitting antenna.

A transmitted signal propagating in free space loses 22 dB in its first
wavelength of travel from the transmitting antenna, 300 meters at 1 MHz,
and then loses an additional 6 dB every time the distance from the
transmitting antenna doubles after that.

So, the tiny phono oscillator with almost no antenna can be heard at a
considerable distance.

Best regards, Richard Harrison, KB5WZI

Science Fair Project
 

On Fri, 09 Feb 2007 17:51:26 -0800, Jim Kelley
wrote:

We can only hope that your unfortunate correspondent
continues trying to imagine it long enough to happen upon the reason.

Jim, If you prefer to think of our correspondent as a shrinking
violet, destiny is already written in the thread. The suggestions
I've offered have been seconded by several others. Do you want to
explain any one or all of them?

73's
Richard Clark, KB7QHC

Science Fair Project
 

"David G. Nagel" wrote in message
...

FCC part 15 regulations specify that a low power am transmitter can not
exceed a very low power level ( I don't remember off hand how much)

http://www.access.gpo.gov/nara/cfr/w...7cfr15_06.html

PART 15_RADIO FREQUENCY DEVICES--Table of Contents
Subpart C_Intentional Radiators
Sec. 15.219 Operation in the band 510-1705 kHz.

(a) The total input power to the final radio frequency stage
(exclusive of filament or heater power) shall not exceed 100 milliwatts.

and the antenna must be attached to the transmitter and must not exceed
about 5 or 6 feet.(b) The total length of the transmission line, antenna
and ground
lead (if used) shall not exceed 3 meters.

Science Fair Project
 

"John" wrote in message
...

The last paragraph of my post got munged. It should be:

and the antenna must be attached to the transmitter and must not exceed
about 5 or 6 feet.


(b) The total length of the transmission line, antenna and ground lead (if
used) shall not exceed 3 meters.

Science Fair Project
 

John wrote:
"David G. Nagel" wrote in message
...

FCC part 15 regulations specify that a low power am transmitter can not
exceed a very low power level ( I don't remember off hand how much)

http://www.access.gpo.gov/nara/cfr/w...7cfr15_06.html

PART 15_RADIO FREQUENCY DEVICES--Table of Contents
Subpart C_Intentional Radiators
Sec. 15.219 Operation in the band 510-1705 kHz.

(a) The total input power to the final radio frequency stage
(exclusive of filament or heater power) shall not exceed 100 milliwatts.

and the antenna must be attached to the transmitter and must not exceed
about 5 or 6 feet.(b) The total length of the transmission line, antenna
and ground
lead (if used) shall not exceed 3 meters.



Thank you for the information. This is something I know but not in
intimate detail. This is what the student was looking for but the dark
side of the net had to have it's way with the subject.

I hope it helps the student with his science project.

Dave Nagel
WD9BDZ

Science Fair Project
 

On Sat, 10 Feb 2007 12:06:06 -0600, "David G. Nagel"
wrote:

I hope it helps the student with his science project.

Hi Dave,

That is of infinite improbability. How many times do we have to tell
adult amateur radio enthusiasts the necessity of matching (a warning
already offered from the shadows of this thread)?

So, shall we consider the merit of a total length of 3 meters in the
AM band? If this discussion is so studiously avoided by those who
weep away about the dearth of information, what chance does a naive
student have to rummage up the details?

The Rr summons up to roughly 20mOhms. Are any of the scolds going to
offer the implications of this value? Are there any suggestions of
using commercial tower sections to cut down on Ohmic loss? Any
matching details for the massive SWR? Any hints on how to load the
structure? Details for a top hat? Would the top hat consume part of
that 3 meter restriction?

Would a loop perform better? What dimensions? How to build the
capacitors? Talk about underwhelming help....

the dark side of the net had to have it's way with the subject.

The dark side is not patronizing with soothing but impotent nostrums.
The topic reduces to one of two resolutions:
1. Deep consideration of many issues;
2. Buy a kit that works as advertised.
One takes many here a lifetime of consideration and books are devoted
to this study, the other satisfies a need.

73's
Richard Clark, KB7QHC

Science Fair Project
 

Richard Clark wrote:

On Fri, 09 Feb 2007 17:51:26 -0800, Jim Kelley
wrote:


We can only hope that your unfortunate correspondent
continues trying to imagine it long enough to happen upon the reason.


Jim, If you prefer to think of our correspondent as a shrinking
violet, destiny is already written in the thread. The suggestions
I've offered have been seconded by several others. Do you want to
explain any one or all of them?

73's
Richard Clark, KB7QHC

So what you're saying is that although you could explain how to make a
loopstick antenna resonate at 1 MHz and properly couple it to a
crystal oscillator circuit, you feel that someone else should do it
for you.

ac6xg

Science Fair Project
 

"T" wrote in message
oups.com...
Thank you mr. kelly for trying to help me out, but obviously richard
is too hostile to want someone else, even a kid, to learn anything
about radio engineering. [you know, since he probably never tinkered
with electronics when he was a kid and asked someone for advice] =
sarcasm

i'm slightly disappointed in him. a grown man, who attacks eager to
learn children over the internet. do you not have friends? a life?

besides if you don't help people, but instead show them hostility,
don't you think they may become discouraged? maybe even give it up and
quit? if there is no one interested in this type of engineering, then
it may cease to exist.

all i'm saying is, be an encourager, help others, and go with god.

"since new developments are the products of a creative mind, we must
therefore stimulate and ENCOURAGE that type of mind in every way
possible." -george washington carver

sorry to be so short, and thanks to everyone who tried to help,
taylor

Oh no! Another victim! This time it is an alleged kid. I thought everybody
gave him plenty of good, free advice.

Science Fair Project
 

On Mon, 12 Feb 2007 18:59:24 -0500, "Stefan Wolfe"
wrote:


"T" wrote in message
roups.com...
Thank you mr. kelly for trying to help me out, but obviously richard
is too hostile to want someone else, even a kid, to learn anything
about radio engineering. [you know, since he probably never tinkered
with electronics when he was a kid and asked someone for advice] =
sarcasm

i'm slightly disappointed in him. a grown man, who attacks eager to
learn children over the internet. do you not have friends? a life?

besides if you don't help people, but instead show them hostility,
don't you think they may become discouraged? maybe even give it up and
quit? if there is no one interested in this type of engineering, then
it may cease to exist.

all i'm saying is, be an encourager, help others, and go with god.

"since new developments are the products of a creative mind, we must
therefore stimulate and ENCOURAGE that type of mind in every way
possible." -george washington carver

sorry to be so short, and thanks to everyone who tried to help,
taylor

Oh no! Another victim! This time it is an alleged kid. I thought everybody
gave him plenty of good, free advice.


Hummm. . . Being "Short", huh? Short would have been simply "Go
jump in the lake, Buddy!"
Hehehehe

FFF

Science Fair Project
 

Richard Clark wrote:
On Sat, 10 Feb 2007 12:06:06 -0600, "David G. Nagel"
wrote:

I hope it helps the student with his science project.

Hi Dave,

That is of infinite improbability. How many times do we have to tell
adult amateur radio enthusiasts the necessity of matching (a warning
already offered from the shadows of this thread)?

So, shall we consider the merit of a total length of 3 meters in the
AM band? If this discussion is so studiously avoided by those who
weep away about the dearth of information, what chance does a naive
student have to rummage up the details?

The Rr summons up to roughly 20mOhms. Are any of the scolds going to
offer the implications of this value? Are there any suggestions of
using commercial tower sections to cut down on Ohmic loss? Any
matching details for the massive SWR? Any hints on how to load the
structure? Details for a top hat? Would the top hat consume part of
that 3 meter restriction?

Richard, I dare say that the 3 meter limit, and the horrible mismatch
achieved with such an antenna just might be part of the whole idea of
part 15 transmission. The user isn't supposed to put much of a signal on
the air. It's supposed to be a technically poor setup.

Of course, assuming that the science fair is taking place in a school
building, the student could operate as a campus transmitter. Lots of
extra steps and paperwork there though.


Would a loop perform better? What dimensions? How to build the
capacitors? Talk about underwhelming help....

Seems like a good way to go for the kid would be to buy a kit or
better, build a radio from scratch, keeping within the legal limits.

Asking for help in here can be confusing enough for a new Ham, let
alone a young schoolkid.




the dark side of the net had to have it's way with the subject.

I have these visions of you making Darth Vader sounds, and saying
"I...am your father T."...... 8^)


- 73 de Mike KB3EIA -

Science Fair Project
 

On Fri, 16 Feb 2007 15:18:36 -0500, Michael Coslo
wrote:

Richard, I dare say that the 3 meter limit, and the horrible mismatch
achieved with such an antenna just might be part of the whole idea of
part 15 transmission. The user isn't supposed to put much of a signal on
the air. It's supposed to be a technically poor setup.

Hi Mike,

All duly offered in the past.

Seems like a good way to go for the kid would be to buy a kit or
better, build a radio from scratch, keeping within the legal limits.

That too was offered.

the dark side of the net had to have it's way with the subject.

I have these visions of you making Darth Vader sounds, and saying
"I...am your father T."...... 8^)

Myself, I would substitute Dark Helmet from "Spaceballs"
"I am your father's brother's nephew's cousin's former roommate."
given the avalanche of other advice that filled the void.

Lone Starr:
"What's that make us?"

Dark Helmet:
"Absolutely nothing!"

73's
Richard Clark, KB7QHC