The really weird thing is that the audio
sounds quite good, although I will
remember both of your suggestions.
Just to test the range of the 49.83 MHz
transmitter, I hung a little two foot transmitting
antenna off of the RF out. I went down the
street with an ICOM R2 scanning receiver.
The transmitter is on the first floor of my house.
The range was at least 500 feet, but then I
started to hear interference from another signal.
Having no desire to listen to this signal, I turned
around and walked back home.
A lot of people have said that the 49 MHz range
is pretty devoid of baby monitors, but I think there
still might be quite a few around.
My main objective is to get an FM solar powered repeater
running. I would like to get these units between
the 49.83 and 49.845 channels. There might be some
way to shift the frequencies slightly with some small caps
in parallel or series with the crystals. If not, I can do
the math and put in some other crystals. Still, I don't
know if 7.5 kHz away will really make a difference as far
as interference is concerned. And if 49 MHz isn't practical,
there are other Part 15 frequencies that can be tried.
Well, anyway, the next step is to get the thing outside
in a package and put it in the sun and see how much
sun it needs to repeat the signals. I have to get some
more solar cells first.
So thanks again SWCIS and Carl. I will keep you guys
posted.
Best Wishes
Bruce, MICRO1690/1700
Your project is coming very well MICRO1700 and to get that sense that I'm playing a part I just tuned my little Alinco DJ-X3 to 49.83mHz to see what happens. Nothing.
Your project is coming very well MICRO1700 and to get that sense that I'm playing a part I just tuned my little Alinco DJ-X3 to 49.83mHz to see what happens. Nothing.
So Carl, in your case that would be great!
With 49.83 empty you could do something
there.
Well, I'm going to wait to get some more solar
cells. I'm also going to measure the current
requirements of the C Crane and the 49 MHz
walkie talkie that is being used as the receiver.
As you know, my projects go very slowly. I am
still working on the Gates board and the 13.560 MHz
transmitter still needs to be completed.
I was able to fix up a nice reel to reel deck - an Akai
GX-4000D.
Right now this solar powered repeater project is
meant to not yield a lot of money. But I could
at some point use a 900 MHz link. Neil built a
nice one a while back with some modules he got
from Digikey. With my vision limitations that might
not be possible right now, but I will still look into it
in the future.
I also believe that Ken, whose Part 15 station is on
a boat, did a remote from a local restaurant. He had
some kind of remote system he used to get from the
restaurant to his Part 15 AM station. However, it
may have been something like a Barix Extremer. (I
sure wouldn't mind having one of those!)
I will keep you guys posted. When I get more solar
cells, the unit will go outside and start functioning.
Best Wishes
Bruce, MICRO1690/1700
So Carl, in your case that would be great!
With 49.83 empty you could do something
there.
Well, I'm going to wait to get some more solar
cells. I'm also going to measure the current
requirements of the C Crane and the 49 MHz
walkie talkie that is being used as the receiver.
As you know, my projects go very slowly. I am
still working on the Gates board and the 13.560 MHz
transmitter still needs to be completed.
I was able to fix up a nice reel to reel deck - an Akai
GX-4000D.
Right now this solar powered repeater project is
meant to not yield a lot of money. But I could
at some point use a 900 MHz link. Neil built a
nice one a while back with some modules he got
from Digikey. With my vision limitations that might
not be possible right now, but I will still look into it
in the future.
I also believe that Ken, whose Part 15 station is on
a boat, did a remote from a local restaurant. He had
some kind of remote system he used to get from the
restaurant to his Part 15 AM station. However, it
may have been something like a Barix Extremer. (I
sure wouldn't mind having one of those!)
I will keep you guys posted. When I get more solar
cells, the unit will go outside and start functioning.
Best Wishes
Bruce, MICRO1690/1700
I took the 49.83/88.3 MHz repeater itself outside and walked
away from the house. My son came with me,
holding an FM radio to listen to the repeated signal.
Again, the signal sounded good through the FM BCB
radio until we encountered interference, (about
500 feet away) so we
turned around and went back home. The repeater worked fine on batteries. (Not enough solar cells to power the unit yet.)
This is with the 49 MHz transmitting antenna still on
the first floor of the house just lying next to
the station turntable. Imagine if the transmitting
antenna was on the roof of the house.
Well, that's another piece of this fun little project
checked out.
Best Wishes
Bruce, MICRO 1690/1700
I took the 49.83/88.3 MHz repeater itself outside and walked
away from the house. My son came with me,
holding an FM radio to listen to the repeated signal.
Again, the signal sounded good through the FM BCB
radio until we encountered interference, (about
500 feet away) so we
turned around and went back home. The repeater worked fine on batteries. (Not enough solar cells to power the unit yet.)
This is with the 49 MHz transmitting antenna still on
the first floor of the house just lying next to
the station turntable. Imagine if the transmitting
antenna was on the roof of the house.
Well, that's another piece of this fun little project
checked out.
Best Wishes
Bruce, MICRO 1690/1700
Have a couple of interesting devices in the toolkit which we used for video work, Sony WCS-990T wireless mics, only a little over $100, available at MCM.
912.600 and 916.112mHz, 2-channels, selectable.
The unit came with a plug-in mic that sounded like a very cheap telephone, but by using a quality microphone the units sound professional, and match a much more expensive Lectrosonic wireless in terms of RF coverage.
This model uses 2-triple A but the newer version uses AA batteries.
Someday I'll test these with a line-level pad as a STL, but there's every reason to expect them to work well. I can hear them on the Alinco Communications Radio.
It's another choice for experimentors to try.
Have a couple of interesting devices in the toolkit which we used for video work, Sony WCS-990T wireless mics, only a little over $100, available at MCM.
912.600 and 916.112mHz, 2-channels, selectable.
The unit came with a plug-in mic that sounded like a very cheap telephone, but by using a quality microphone the units sound professional, and match a much more expensive Lectrosonic wireless in terms of RF coverage.
This model uses 2-triple A but the newer version uses AA batteries.
Someday I'll test these with a line-level pad as a STL, but there's every reason to expect them to work well. I can hear them on the Alinco Communications Radio.
It's another choice for experimentors to try.
900 MHz. Absolutely! It was probably come to
that eventually.
Thanks so much!
Bruce, MICRO1690/1700
900 MHz. Absolutely! It was probably come to
that eventually.
Thanks so much!
Bruce, MICRO1690/1700
Bruce, congrats on your progress with your project. It is very good of you to share the blow by blow steps as this is not only interesting but informative about how projects progress.
You have a good memory regarding my work with the 900 MHz modules since it has been a while since I reported on this. Since you mentioned this, I will share an update. My project was to wirelessly link a Doppler radar speed unit with the link between the Gunn diode head and the speed display unit. The Gunn unit produces an audio signal in the tens of microvolts range with a frequency span of 250 to 3 kHz. It took a lot of work to get the signal conditioned and amplified before it is sent into the transmitter input. One big problem was signal to noise ratio but I managed to design an amplifier which works well with the intent of maximizing the input to the transmitter rather than applying gain at the receiver. This is so noise in the link doesn't get amplified.
I am able to measure the spectrum and signal to noise ratio of the received signal and it worked out very well with a S/N of 45 dB comparing the tone to the white noise. Doppler radar audio contains a lot of noise due to artifacts such as thermal air currents, neighbors' sprinklers, trees moving with wind, and birds. I clocked birds here at 20 MPH.
When I interrupt the audio signal into the transmitter the link receiver quieting is 60 dB which is excellent. I have not found the maximum range yet but the received signal is excellent even when the transmitter is 100 feet away in my yard and the receiver is in my basement underground with the signal having to penetrate stucco siding with a wire mesh behind it and the intermediate sheathing with foil. Usually my other toys' (rain gauge, outdoor temp. sender, and motion detector) 433 MHz signals have difficulty penetrating which limits their usable range to about 10 feet outside my house.
I am using home brew quarter wave ground plane antennas for transmit and receive. These are tiny due to the high frequency, measuring about 8 cm. length on the elements. I had intended to build Yagis but didn't need to since the link range is adequate for what I am doing so I don't know what the capabilities of this would be. The manufacturer cites a typical range with simple antennas of 1000 feet which is believable based on what I have experienced. A real range test is on my list of things to do and since it has taken me 9 years so far to get to where I am with this it may be a while before I do the range check.
So, the upshot of this long report is to relate my positive experience using 900 MHz part 15 links. The particular units I have are no longer made but there are many other similar ones available in the $30 per unit range.
Neil
Bruce, congrats on your progress with your project. It is very good of you to share the blow by blow steps as this is not only interesting but informative about how projects progress.
You have a good memory regarding my work with the 900 MHz modules since it has been a while since I reported on this. Since you mentioned this, I will share an update. My project was to wirelessly link a Doppler radar speed unit with the link between the Gunn diode head and the speed display unit. The Gunn unit produces an audio signal in the tens of microvolts range with a frequency span of 250 to 3 kHz. It took a lot of work to get the signal conditioned and amplified before it is sent into the transmitter input. One big problem was signal to noise ratio but I managed to design an amplifier which works well with the intent of maximizing the input to the transmitter rather than applying gain at the receiver. This is so noise in the link doesn't get amplified.
I am able to measure the spectrum and signal to noise ratio of the received signal and it worked out very well with a S/N of 45 dB comparing the tone to the white noise. Doppler radar audio contains a lot of noise due to artifacts such as thermal air currents, neighbors' sprinklers, trees moving with wind, and birds. I clocked birds here at 20 MPH.
When I interrupt the audio signal into the transmitter the link receiver quieting is 60 dB which is excellent. I have not found the maximum range yet but the received signal is excellent even when the transmitter is 100 feet away in my yard and the receiver is in my basement underground with the signal having to penetrate stucco siding with a wire mesh behind it and the intermediate sheathing with foil. Usually my other toys' (rain gauge, outdoor temp. sender, and motion detector) 433 MHz signals have difficulty penetrating which limits their usable range to about 10 feet outside my house.
I am using home brew quarter wave ground plane antennas for transmit and receive. These are tiny due to the high frequency, measuring about 8 cm. length on the elements. I had intended to build Yagis but didn't need to since the link range is adequate for what I am doing so I don't know what the capabilities of this would be. The manufacturer cites a typical range with simple antennas of 1000 feet which is believable based on what I have experienced. A real range test is on my list of things to do and since it has taken me 9 years so far to get to where I am with this it may be a while before I do the range check.
So, the upshot of this long report is to relate my positive experience using 900 MHz part 15 links. The particular units I have are no longer made but there are many other similar ones available in the $30 per unit range.
Neil
Thank you for your wonderful report on your
remote Doppler radar setup. I have read it
several times, and plan to look at it some more.
I know a lot of hams and radio people. A lot of
these people love science and venture into
projects that go beyond radio. One ham friend
built an earthquake detector. Rumor has it, that
the detector was so sensitive, he was able to tell
when a shuttle was being launched in Florida,
which is a long way from Connecticut.
There was one ham who enjoyed listening to radio
emissions from Jupiter, something I have always
wanted to do. (But I have never gotten around to it.)
Some hams have followed spacecraft partway to Mars
and I think somebody somewhere achieved Venus-Bounce.
I know a guy who used a gigantic IR LED array to make
contacts with other IR enthusiasts. They bounced the
IR emissions off of a large tall building in a nearby city
that they could both see from their locations. They also
used cloud-bounce.
Some people build robots. Others build rockets that use
Mentos mints and Diet Coke for fuel. One guy even mounted
a homemade jet engine on a super market shopping cart.
When the engine was operating, the sides of it glowed the
color red from the heat.
Still, you are the first person I know of that built a real radar
unit and then sent an RF link back to your house.
Wow! That's really something! You obviously have a great
deal of knowlege.
In this solar powered Part 15 repeater, I am really interested
in the solar power aspect of the thing and how that works.
Also, it is a very easy thing to put together, unlike some of
the other projects I am slowly working on. And if I ever
get to working with 900 MHz modules, I will have some
questions for you.
I thought of one more funny project. When a local radio
buddy and I were kids, Radio Shack made something called
A "Big Ear." It was just a microphone inside of a big
plastic parabolic dish on a tripod. It had an audio amplifier
in it with headphones, and theoretically, you were supposed
to be able to hear people talking far away, and that sort of
thing. My friend put it in his front yard, and ran an audio
cable to his stereo system in the cellar. Turn up the volume
on the stereo,
and (he claims this, but I don't remember it) we could hear
the guy in his yard 300 feet away telling his dog to - well,
we all know what dogs do outside. But we had to be careful.
One day neither of us were near the volume control on the
stereo. A car with a bad muffler came down the street, and
we practically got blasted out of the room!
Thanks Neil for the great writeup.
Best Wishes,
Bruce, MICRO1690/1700
Thank you for your wonderful report on your
remote Doppler radar setup. I have read it
several times, and plan to look at it some more.
I know a lot of hams and radio people. A lot of
these people love science and venture into
projects that go beyond radio. One ham friend
built an earthquake detector. Rumor has it, that
the detector was so sensitive, he was able to tell
when a shuttle was being launched in Florida,
which is a long way from Connecticut.
There was one ham who enjoyed listening to radio
emissions from Jupiter, something I have always
wanted to do. (But I have never gotten around to it.)
Some hams have followed spacecraft partway to Mars
and I think somebody somewhere achieved Venus-Bounce.
I know a guy who used a gigantic IR LED array to make
contacts with other IR enthusiasts. They bounced the
IR emissions off of a large tall building in a nearby city
that they could both see from their locations. They also
used cloud-bounce.
Some people build robots. Others build rockets that use
Mentos mints and Diet Coke for fuel. One guy even mounted
a homemade jet engine on a super market shopping cart.
When the engine was operating, the sides of it glowed the
color red from the heat.
Still, you are the first person I know of that built a real radar
unit and then sent an RF link back to your house.
Wow! That's really something! You obviously have a great
deal of knowlege.
In this solar powered Part 15 repeater, I am really interested
in the solar power aspect of the thing and how that works.
Also, it is a very easy thing to put together, unlike some of
the other projects I am slowly working on. And if I ever
get to working with 900 MHz modules, I will have some
questions for you.
I thought of one more funny project. When a local radio
buddy and I were kids, Radio Shack made something called
A "Big Ear." It was just a microphone inside of a big
plastic parabolic dish on a tripod. It had an audio amplifier
in it with headphones, and theoretically, you were supposed
to be able to hear people talking far away, and that sort of
thing. My friend put it in his front yard, and ran an audio
cable to his stereo system in the cellar. Turn up the volume
on the stereo,
and (he claims this, but I don't remember it) we could hear
the guy in his yard 300 feet away telling his dog to - well,
we all know what dogs do outside. But we had to be careful.
One day neither of us were near the volume control on the
stereo. A car with a bad muffler came down the street, and
we practically got blasted out of the room!
Thanks Neil for the great writeup.
Best Wishes,
Bruce, MICRO1690/1700