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

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 -

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

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?

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

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

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

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

"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

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