Though not Part 15, AM radio stations use coils not ferrites in the output to the antenna, even for those stations that run under 100 watts at night.
Hi Neil and everyone.
Wow it been a while since I have been up here. Ok I know Coils. I was in a world
Wide Crystal radio contest for year and even placed 3rd in the contest. We would design Crystal radios that worked in the Broadcats band and thes radio would pick up
thousands of miles on the AM broadcast band and even weak signals. You ask what does this have to do with Transmitting Low power signals. Well First we needed very
high Q coils and we had to have the antenna;s matched up to the receiver and the output matched up to very sensitive headphones. First off lets go with the different types of wires.
The most common wire. Copper Magnetic wire.
When these coils are wound the wire is closely would. Result this causes a lot
of cpacitance in the coils. Ok in the 1920's this is why you saw spider web coils
and honey comb coils to reduce this capacitance in these coils to raise the Q point.
If you are going to use maganetic wire you can raise the Q by placing a space
between each turn. The space would be equal to the dianeter of the wire. This will
increase the Q of the coil.
Anothe wire that use seen in older Radio of the 1920;s was the silk cover wire.
See the silk would actually give a space between each turn on the coil because
the silk covered the actual wire and the silk added to the width of the wire.
Also professional designers of the time again would make spider web coils and
honey comb coils to raise the Q point even higher.
Lizt wire is another wire with it cover that give you also a space between each turn.,and I have made very high Q coils with this wire and they worked quite well
at 1700Khz.
Now if you are going to use a capcitor to tune up the antenna the best is the
true Silver capacitors with ceramic insulators.
What you are trying to achieve is a ver high Q point ,so your antenna will tune up
very sharp and have very little loss.
Yesting antennas is very easy. Get a very good Field strength meter,and make sure
it has a meter and not some led Read out. Meters will show even slight changes.
I actually place my Field strength about 2.5 feet away from the antenna that I test.
I plug and play different coils into my atenna to see which coils perform the best.
There is also a Coil Calculator on the Web that can calculate the Q of the Coil.
Yes I would say the Ferite coils would not perform well due to temperture changes.
This is if you plan on an out side type antenna.
Please look at the antenna;s made for CB radio magamount antennas and even ham
radio anteanns with loading coils. You will never see one made with a iron core,
or ferrite core. Alot of them use magnetic wire but on the better antennas the
coils turns are spaced apart on a ceramic core.
If you are going to have a coil in the out doors ,please place some covering over
it to protect it from the rain. Rain can change the performance on and antenna
that uses a loading coil. One the antenna is dry again it will go back to it normal
performance.
I have been trying to design the best perfoming antenna ever made for LPAM.
I actually came up to see if anyone else had good ideals for a great antenna
with low loss and a high field strength. If you design an antenna take field
strength readings on it . This is the only way to see how well an antenna is
performing. The higher the Field strength you get out of the antenna the
greater the range of your station will get out.
This is why I really wish Procaster would publish Field strengths and
also the Range Master. the Field strength coming off the antenna will determine
the range of the transmitter.
Let just say you are getting the full power of 100mw out of your transmitter.
Then there is no room for improvment on the transmitter. The only area left
is the antenna for improvement. I know everyone is trying to get the antenna
matched up. Take in consideration. Your loadind will determine if you have
a 1/4 wave anteanna, or 1/2 wave antenna,or even a 5/8 of a wave anteanna
wich has gain over a diopole. Remeber ham and CB radio opperators have 5/8
wave anteanna on their vehicles. But these antenna are not 5/8 wavr long.
They use coils to acheive this and then they get antenna with gains of 2.5db
to even 5.6db gain over a dipole. Realize we can use the coils in the same
way to take a 10ft whip and make it a 5/8 wave anteanna by just using the correct
coil cinfiguration. Then you 10ft antenna would longer have losses but would
have gain over a dipole.
I am a electronic Engineer and have designed many antennas. I also work ham radio
and work QRPP . I usually only run less that a 1/2 watt SSB on the have band
and have made contacts all over the world. I also run a 2 meter ham Station
that only outputs 100mw and I hit repeaters over 50 to 100 miles away from me.
I also talk simplex and that usually cut out around 20 to 25 miles. Not
bad since I am only running 100mw. I really think if we can find a way to load a
10ft whip with a correct coil that a remarkable distance could be reached.
Like you guys I want to have my station get out as far as possible. At this
point we have good transmitters. We need the best designed antenna ever made for
LPAM. If your transmitter has a 50 ohm output which alot do. Even my
Talking Sign TS 100 Transmitter which was about $600 when it came out.
This radio has a antenna tunner built inside and you have to manually tune it up
to the 10 ft antenna. Now it also has the option for the 50 ohm output for your
own antenna. Most the transmitters on the market have a 50 ohm output.
For the exception of th Procaster and Range master. These you get what you get
since the antenna is built on these transmitters. For the rest of us we need
to design a really great antenna.
Again when I design antennas I set them up under the same test conditions and
take field strength reading. This tells me what each coil performance is under
real conditions.
Anyways I am open up to any sugestions,but I have the land and area to test antennas
I live very far out in the country . Very far from any broadcast stations.
I have been thinking up an antenna that could work on top of a metal roof building.
A magmount anttena for a metal roof building, The metal roof acts as your ground
plain and the base load antenna would have a very high gain if set up as a 5/8
wave antenna.
I am very serious about design a professional antenna for the LPAM transmissions.
Thanks
Hi Neil and everyone.
Wow it been a while since I have been up here. Ok I know Coils. I was in a world
Wide Crystal radio contest for year and even placed 3rd in the contest. We would design Crystal radios that worked in the Broadcats band and thes radio would pick up
thousands of miles on the AM broadcast band and even weak signals. You ask what does this have to do with Transmitting Low power signals. Well First we needed very
high Q coils and we had to have the antenna;s matched up to the receiver and the output matched up to very sensitive headphones. First off lets go with the different types of wires.
The most common wire. Copper Magnetic wire.
When these coils are wound the wire is closely would. Result this causes a lot
of cpacitance in the coils. Ok in the 1920's this is why you saw spider web coils
and honey comb coils to reduce this capacitance in these coils to raise the Q point.
If you are going to use maganetic wire you can raise the Q by placing a space
between each turn. The space would be equal to the dianeter of the wire. This will
increase the Q of the coil.
Anothe wire that use seen in older Radio of the 1920;s was the silk cover wire.
See the silk would actually give a space between each turn on the coil because
the silk covered the actual wire and the silk added to the width of the wire.
Also professional designers of the time again would make spider web coils and
honey comb coils to raise the Q point even higher.
Lizt wire is another wire with it cover that give you also a space between each turn.,and I have made very high Q coils with this wire and they worked quite well
at 1700Khz.
Now if you are going to use a capcitor to tune up the antenna the best is the
true Silver capacitors with ceramic insulators.
What you are trying to achieve is a ver high Q point ,so your antenna will tune up
very sharp and have very little loss.
Yesting antennas is very easy. Get a very good Field strength meter,and make sure
it has a meter and not some led Read out. Meters will show even slight changes.
I actually place my Field strength about 2.5 feet away from the antenna that I test.
I plug and play different coils into my atenna to see which coils perform the best.
There is also a Coil Calculator on the Web that can calculate the Q of the Coil.
Yes I would say the Ferite coils would not perform well due to temperture changes.
This is if you plan on an out side type antenna.
Please look at the antenna;s made for CB radio magamount antennas and even ham
radio anteanns with loading coils. You will never see one made with a iron core,
or ferrite core. Alot of them use magnetic wire but on the better antennas the
coils turns are spaced apart on a ceramic core.
If you are going to have a coil in the out doors ,please place some covering over
it to protect it from the rain. Rain can change the performance on and antenna
that uses a loading coil. One the antenna is dry again it will go back to it normal
performance.
I have been trying to design the best perfoming antenna ever made for LPAM.
I actually came up to see if anyone else had good ideals for a great antenna
with low loss and a high field strength. If you design an antenna take field
strength readings on it . This is the only way to see how well an antenna is
performing. The higher the Field strength you get out of the antenna the
greater the range of your station will get out.
This is why I really wish Procaster would publish Field strengths and
also the Range Master. the Field strength coming off the antenna will determine
the range of the transmitter.
Let just say you are getting the full power of 100mw out of your transmitter.
Then there is no room for improvment on the transmitter. The only area left
is the antenna for improvement. I know everyone is trying to get the antenna
matched up. Take in consideration. Your loadind will determine if you have
a 1/4 wave anteanna, or 1/2 wave antenna,or even a 5/8 of a wave anteanna
wich has gain over a diopole. Remeber ham and CB radio opperators have 5/8
wave anteanna on their vehicles. But these antenna are not 5/8 wavr long.
They use coils to acheive this and then they get antenna with gains of 2.5db
to even 5.6db gain over a dipole. Realize we can use the coils in the same
way to take a 10ft whip and make it a 5/8 wave anteanna by just using the correct
coil cinfiguration. Then you 10ft antenna would longer have losses but would
have gain over a dipole.
I am a electronic Engineer and have designed many antennas. I also work ham radio
and work QRPP . I usually only run less that a 1/2 watt SSB on the have band
and have made contacts all over the world. I also run a 2 meter ham Station
that only outputs 100mw and I hit repeaters over 50 to 100 miles away from me.
I also talk simplex and that usually cut out around 20 to 25 miles. Not
bad since I am only running 100mw. I really think if we can find a way to load a
10ft whip with a correct coil that a remarkable distance could be reached.
Like you guys I want to have my station get out as far as possible. At this
point we have good transmitters. We need the best designed antenna ever made for
LPAM. If your transmitter has a 50 ohm output which alot do. Even my
Talking Sign TS 100 Transmitter which was about $600 when it came out.
This radio has a antenna tunner built inside and you have to manually tune it up
to the 10 ft antenna. Now it also has the option for the 50 ohm output for your
own antenna. Most the transmitters on the market have a 50 ohm output.
For the exception of th Procaster and Range master. These you get what you get
since the antenna is built on these transmitters. For the rest of us we need
to design a really great antenna.
Again when I design antennas I set them up under the same test conditions and
take field strength reading. This tells me what each coil performance is under
real conditions.
Anyways I am open up to any sugestions,but I have the land and area to test antennas
I live very far out in the country . Very far from any broadcast stations.
I have been thinking up an antenna that could work on top of a metal roof building.
A magmount anttena for a metal roof building, The metal roof acts as your ground
plain and the base load antenna would have a very high gain if set up as a 5/8
wave antenna.
I am very serious about design a professional antenna for the LPAM transmissions.
Thanks
Hi everyone
I could not get my lat post edited. The screen was jumping all around.
Anyways wher I talk about maganetic wire. The turns in a single layer coil
are closely wound and this adds stay capacitance and lowers the Q of the coil.
This in return would cause high losses in the loading coil and you end up with
a lower field strength at your antenna.
This rest is explain in my othe post
Thanks
Realize we can use the coils in the same way to take a 10ft whip and make it a 5/8 wave anteanna by just using the correct coil cinfiguration.
Adding a loading coil at the base of a ~3-meter vertical radiator can make it resonant in the medium-wave broadcast band, but unfortunately that will not make it the equivalent of a radiating conductor that is naturally resonant without needing a loading coil -- such as vertical monopole conductor that is physically about 1/4-wavelength long.
Resonating (coil loading) an electrically short monopole antenna permits the most efficient transfer of power from the output of the transmitter to the base of the short radiator, but still the amount of that power that is actually radiated by that antenna system will be very small, because a 3-meter antenna system has very low radiation resistance* in the MW broadcast band -- about 1/10 of an ohm at 1600 kHz (less for lower frequencies).
The radiation resistance of a conductor is dependent on the physical length of that conductor in space and the operating frequency, and independent of whether or not that conductor is resonant at the operating frequency. The radiation resistance of a base-loaded, resonant ~3-meter antenna is the same as when it is unloaded and non-resonant.
The ratio of the radiation resistance to the sum of the radiation resistance plus all other resistances in the antenna system determines how much of the available power is radiated.
The power radiated by a base-loaded, resonant, ~3-meter vertical monopole antenna system at 1600 kHz is on the order of 0.25% of the output power of the transmitter, depending on the r-f resistance of the loading coil and connection to r-f ground. This assumes that the base of the 3-meter antenna is located not more than a few inches above the earth, and connects to a buried r-f ground via a ~2" long conductor.
* see http://en.wikipedia.org/wiki/Radiation_resistance
The limiting factor for performance of AM part 15 antennas seems to be the ground system. Here, I use a base coil loaded vertical ground mounted over 12 ten foot radials and get a range of just a bit over a mile. The coil is a 3 inch diameter close wound magnet wire unit which gives a Q of 180. This could be made much better in terms of Q but doing so would give only incremental advantage over what I have because most of the power loss is in the ground system.
Nonetheless, if you do design your "best" antenna I hope you will share the details with us.
Neil
Imagination is strongest when it is uninformed. This is the state of mind when it is possible to believe that there is "something more","Some new way to do it","A new idea." I try to preserve my imagination by remaining somewhat ignorant, because I enjoy believing in "breakthroughs in antenna science" which one of us will discover any day now.
Meanwhile, it is good to hear from voices dedicated to the known laws of physics, who at times seem like "standard bearers for reality" and at other times seem "lacking in any inventive sense."
Overall, on a planetary scale, the human race is failing catastrophically due to a mix of science and ignorance. Perhaps Part 15 radio is no different.
Overall, on a planetary scale, the human race is failing catastrophically due to a mix of science and ignorance.
To the extent that the above clip might be true, wouldn't such failure be attributed more to ignorance, than to science?
Quote Seankw40..
"If you are going to use maganetic wire you can raise the Q by placing a space between each turn."
Why not wind simple magnet wire with heavy fishing line about the same O.D. beside each other to provide spacing? Hillbilly Hi-Q Coil..
Science has killed the Gulf of Mexico, made the Pacific Ocean radioactive, loaded the land and waterways with toxic substances, subjected living bodies to microwave radiation.
Ignorance persists in high places with a supreme court justice telling us that the devil is real, other religious celebrities blocking population control and the new agers pushing arificial knowledge in healthcare and superstition.
The observant journalist can do little more than point out the flaws, but those in power are swept up in narcicistic hubris and believe they are insulated.
That about covers it.
I think the fishing line is a good suggestion.
I like the way you think Blare!
Hi Yes
The fishing line is a great ideal. The whole ideal of the space between the
coil is to lower the capacitance between the turn of the coil which
does result in a higher Q. Just look at the older radios that used silk or cotton
cover wire and that silk and cotton actually provided the spacing between the
turns. Now they the really knew what they were doing back in the 1920's and
1930's when winding coils. See I have electronic magazines dating from 1905 to
the late 1920's. Now the one in the early 1920's the showed and talked about
how to get the higher Q;s out of their coils since low Q coils would cause
a lower selectivity in their crystal radios which would cause station not to
be separate very well when tuning. Also the higher Q coils would help produce
radios that would be morw sensitive. They also were trying to match wire
antenna;s to these radios,so they would have antenna tuners that used a coil
at the base of the antenna with a capacitor to tune the antenna up to the
receiver for more tranfer from a short wire to the receiver.
We are trying to do the opposite get more power from the transmitter to the 10
foot wire,copper pipe ,or what ever you want to use.
Now they used Spider web coils, honey comb coild due to lower surface capacitance,
and this rusulted in higher Q coils. I will find the coil calculator on line and post the link to it. This will help in the design in coils and actually tell
you the Q of your coil before you even construct it.
Yes a great ground system is needed. Now realize the the Range master transmitter
and Procaster transmitters. Are always talked about how high to mount them in the
air. I have actaully have the original paper work for the range master
where it says to mount the antenna about 15 to 30 ft in the air. This results
in no ground plan for this antenna. Adding ground radial under the antenna then
make it no longer comply to the FCC rules. Now the range master with a 8 ft
CB antenna could only have 2 ft radials placed under the antenna to keep in in compliance to the FCC. So an antenna placed closer to the ground really comes closer what the FCC allows. Remember one thing that AM broadcasting is more of
a ground wave signal anyways. So with these lower frequencies that ground
wave work really great. So a better ground is the real key to this type of
transmitting. Now the FCC never place how long your ground wires could be.
Your rediator is limited to the 10ft or 3 meters . How ever you want to look at
it. If you want to burry 125 radials in the ground there is no rules on this.
I found that 16 of the 125 ft ground radial work perfect. I have seen professional
stations use bare wire or even heavy insultated wire burrued under the ground.
I have even help set up some of these stations. Since I am a license Technition
local radio stations still call on me to make sure they are working correctly.
Imagination is a great ideal,and if you have an ideal on a new antenna. I say
go for it. Most the best things found out were stumbled on by someone thinking
it could be possible. Realize that eddison tried to make the light bulb and he had
over 2000 test that the light bulb did not work. They were not failers he just found 2000 ways not to make a light bulb before he found the one way to make one
that worked. So we may have to make thousands of antenna;s till we hit the one
that really does what we want it to do. If we do not try then we may never find
that pefect antenna. Just look at the transmitters now. The FCC gave us that 100mw
DC input to the final. Well for years people would make transmitters and be lucky
to get 25mw output ,and look now we have transmitters that are almost putting out
100 percent of that 100mw DC input. Rangemast told me most their transmitters are
outputing anywhere from 95 to 98 mw. WOW and now the transmitter 5000 claims
almost a 100 percent output from the 100mw DC input. These are really advancements
since the 1980;s and 1990;s where most transmitter would only have 20 to 40 mw
outputs. Now that we have these great transmitters that output almost the full
100mw it now the time to find the most effiecent antenna possible. Yes the FCC
made the 2 meter or 10 ft limit on the antenna. I know they never imagine that
the transmitter would have almost the full 100mw output. I have the write up from
the FCC in 1990. It says 100 mw DC input but it says with a output of 50mw.
They in 1990 though the best transmitter could never exceeed 50 mw output.
Well we have exceeded what the FCC never thought could be done.
Now it time to find that antenna that will show how well designed these transmitters were done. We had some really smart people who came up with these
transmitters that are almost 100 percent effiecent. That almost unheard of in anything. Most things are never 100 effiecent. I constantantly trying to design
an antenna that will work better. Realize that a metal roof can act as a great
ground. This is one way to get elevation on an antenna. If the building you are
in a antenna in a magmount form can make a great ground. The ground would be
privided through capacitance. This is how CB radio antennas on cars works.
See they get a ground through the car paint theough capacitance. So it we can
design a magmount antenna with a 10ft whip that could be attached to a metal building or a bulding with a metal roof. this would give you a large ground plain
with also the antenna being elevated in the air. This would provude extra range,
because now you would have a great ground and hight on your antenna.
The antenna may not gain more effiecenty but you would now have a great ground
only found close the the earth ground, but also now you would also have the hight that you would not have if your antenna only inches above the earth ground.
This antenna would be still in FCC compliance since you do not have a direct
ground connection. Your ground would be only provided through capacitance,
When the FCC see the paint on the metal surface they cannot claim a ground
connection to your transmiter. Yet you would have a true ground connection but
through capacitance. Cb Magmounts use this ground connection all the time.
This is why a CB magmount antenna will not tune up correctly with out that ground
under it. Most CB Magmount antennas are 1/4 wave ground plain antenna. The
metal roof on your car is the other have of your CB antenna, This same consept
can be used to make us an antenna that works in that same way.
So we could have a 10ft antenna with a metal roof to act as our ground plain.
Any buiding with a metal roof would work. Metal shed, Metal building,and even
a trailor home with a metal roof. Again you would have the great ground you are looking for and you could base load the 10ft whip for propper tuning to the frquency being transmitted on. I know when this thread was start that you were
looking for a new antenna for the 5000 transmitter. Well this is a new antenna
that has never benn brought up in any thread. I just ask think about this type
of antenna since it would give you the height and and constant good ground.
Earth grounds can change from summer to winter. The metal roof ground would be
a good constant ground.
Just think about it and that all I ask.
Thanks
And the cloth colored wire!
Radios from the 1920s and
1930s had that.
Bruce, DOGRADIO
Yes you are correct and that cloth would give spacing between the actual conductor.
Where thin paint and magnetic wire gives no spacing at all.
Great thought.
Thanks
Sean
Thinking back about cloth covered wire, I think it might have picked up moisture, which would defeat the spacing and introduce capacitance.
Old house wiring was a kind of cloth which seemed to be saturated with a wax or something, but it's all crumbling now and if any of it is still in old homes it can be a fire risk.
Also, I remember cloth wire getting frayed, like on flat-irons with women or helpful men ironing shirts and rubbing the wire up and down on the edge of the ironing board.
I'll bet some standards body found cloth wire unsafe.