A year or more ago, we had a long thread on how
to make an AM transmitter for 13.560 MHz.
Actually, it was one of the longest and most
popular threads on this board.
A year or more ago, we had a long thread on how
to make an AM transmitter for 13.560 MHz.
Actually, it was one of the longest and most
popular threads on this board.
First, I'll just make a note for those of us who weren't here or haven't
heard of that frequency range. This Part 15 band runs from
about 13.553 to 13.567 MHz, which can be tuned in on most
shortwave radios. All of our previous calculations
for power output came out this way: The rule permitted a certain
field strength which was calculated to be about 1 - 2 milliwatts
into a full size dipole. This is more effective radiated power
than permitted on the Part 15 AM, FM, and 27 MHz bands.
(Some other Part 15 bands allow more, though.)
Both Carl Blare and I started to build transmitters. Some other
Part 15 experimenters had done this before, but Carl and I
started out with a clean slate. We both constructed a readily available
and inexpensive ham radio transceiver kit. This was called the
Pixie 2. Carl was able to successfully AM modulate the transmitter
section, with parts he obtained from various vendors. If I remember
correctly, Carl came up with about 7 or 8 milliwatts out with
100 percent modulation. He ran a small transmitting antenna for
testing so the set-up was legal. Neil and a bunch of other
people on the thread (forgive my bad memory)
provided all sorts of great input as we
were trying to get these transmitters to light up.
Because of eyesight limitations, my transmitter turned
out to be very different and a lot simpler. It was just
a 5 milliwatt (input) 13.560 MHz crystal controlled amplitude
modulated oscillator. With it running untuned into a dipole
cut for that frequency, I was able to hear it for about 1000
feet on a shortwave portable. I used a ham radio antenna
tuner to suppress any harmonics. If I attempted to tune
the output of the transmitter with an LC, it would FM, which was
undesirable.
My only real goal was to have a Part 15 SW transmitter so my
ham radio friend could hear my station in his ham shack, a
mile away. As of now, this has still not been achieved.
Along the line in these experiments, we talked about using
DSB as a transmission mode. This would be fairly easy to
construct, and would go farther than an AM SW transmitter.
DSB is sort of an AM signal without the carrier. The person
receiving would use his communication receiver to reinsert
the carrier.
People thought this would be OK for talk radio programming.
I have actually heard shortwave broadcasters use LSB or USB,
which is pretty much like DSB. Many years ago, I listened to
a radio show called, "Glenn Hauser's World Of Radio." It was
aired on RFPI - Radio For Peace International. This station
no longer exists, but it had some LSB transmitters along
with some AM ones. Music sounded very weird on LSB, but
it can be tuned in, especially if you have a sense of humor.
I was puttering around on the internet today and a came
across a web page entitled, "A Simple Modular DSB TX.
In fact, if you google this title, you will get the page.
This transmitter starts out with a single DSB module,
which consists of an NE602 mixer. The mixer is hooked
to a mike and a crystal, and with a few other parts.
Apparently, you come up with a DSB generator that
puts out about a half a milliwatt. (Maybe less, it was
hard to read the writing.) The NE602 also acts as the
crystal oscillator. The circuit pictured on this
page was made to run on the 160 or 80 meter amateur
radio bands. There is also a link to a page which shows
a rough schematic for a linear amplifier, that is capable
of several hundred milliwatts (much more than we need.)
I do not recognize the transistors in that schematic, but
there isn't much too it. There is no output filter
shown, but we already have that information in the
previous 13.560 Part 15 shortwave transmitter thread.
So I am throwing this out again for you all to look at,
for whatever it's worth. I can only build really simple
circuits, because of eye limitations. Maybe this one
is worth trying. (For me, anyway.)
Best Wishes
Bruce, MICRO1690/1700
enhanced single sideband - eSSB - hi fi ssb. ssb properties, b,cast quality audio.
MICRO 1700 I'm happy you are bringing back the 13.56mHz subject. For anyone curious about the transmitter I constructed look no farther
http://www.kdxradio.com/pixie2.html
Only this afternoon I was thinking that I'm overdue in mounting the circuit cards in a box and putting up a serious outside antenna. Since proofing the project months ago the parts have been packed in a storage box.
MICRO1700 is the project leader on the DSB Version, I am not so keen that I'd know where to begin, having no HAM experience.
I'm the project leader? Uh, oh.
Bruce, MICRO1690/1700
P.S. And thanks KC8GPD for the
posting about eSSB. I'll look it up.
Now if only we could get some skywave outta the thing 😉
So far the closest International Broadcast made was by myself and MRAM on Hamsphere
This looks all pretty neat, but beyond my knowledge (as usual).. However, I should point out that Carl should not be trying to shadily pawn his responsibilities off on Bruce as the project leader (unless of course Bruce sees fir to take on the responsibility)...
After all, the schematic page link above officially states: "Carl Blare, Half-Baked Project Director".
If Bruce is indeed to become the project leader of experimentation of this curious little transmitter, then the official statement needs to be changed to "Microman; Half Baked Director with two frequencies".
Otherwise there's bound to be conflict in the future.
Get it right people.
I've got plenty of experience with being half baked, so I know what I'm talking about.
It's a good thing I'm here to straighten this matter out before it becomes a problem
RichPowers
Since titles are being handed out, will you serve as Director of Directors?
That way all of us directors will have a director.
I have to decline that offer. I better suited to go after the coffee and doughnuts. I'm also pretty good at holding a flashlight and handing over the tools. I even know how to answer the phone.
Don't let me wire up your transmitter though.. two wires... hmmmm... eni meeni miney mo...
Carl,
Maybe you could be the project's Benevolent Dictator...or Tator Salad...or...(fill in the blank). LOL.
I am visualizing your throne, crown and scepter. Whew!
If you were the Director of the Directors, but had no direction, would that make you aimless? That comment is probably more on target than off, eh?
Hearkening back to the days in the Navy, if you are the Project Head, that would make you....
But seriously folks, purumpum.
Well, I guess it's me.
I have no money, no time, and can't see
very well, so I guess everything's already
in place!
I'll try to scrounjsh (?) up an NE602 from
somebody somewhere, and get the other
seven or eight parts needed for the exciter.
An audio source is no problem. I have
a 13.560 crystal from the other transmitter,
so that's no problem. I'll have to calculate
the values for the external components for
the NE602.
Then there is the linear amp. We only need
a couple of milliwatts, but it will have to be
linear, so it will not be very efficient. It will
have to run maybe 10 or 20 milliwatts input.
Maybe I can take one of those buffer circuits
from the old Medium Wave Alliance website
and get it to run class A (?). (If it's biased
right?)
Then there is the RF output network. We
already know how to do that.
This is going to take me a very long time so
don't hold your breath, but I will start working
on this. It can go along with the Gates board
project, the solar powered Part 15 repeater,
and the new AM transmitting system.
If you guys have any input, let me know.
Best Wishes,
Bruce, MICRO1690/1700
Bruce, when you ask for input, I understand that is an order, direct from the self-declared dictator.
Marshall,
Aimless? Is it that obvious?
Throne? Do you mean in the Navy sense?
Last night I tuned to 13.56 and listened to the background noise where my transmitter could be if it were finally in a project box and hooked up. Gotta do it. Bruce, order me to do it.
RichPowers, I could use a cup of coffee and some lunch.
Note to self: try not to be slap happy.
Bruce,
You might also consider the MC1496 chip for your project. I used this chip when I taught communications lab and it worked very well. The circuit I used is in Figure 24 of this data sheet:
http://www.datasheetcatalog.org/datasheet2/c/0gh5wy71w3dsw8x23f8l8pw8d97y.pdf
The pot allows adjustment of the carrier insertion all the way from none (DSSB) to unity (AM). The modulation linearity I observed (with scope and spectrum analyzer) is excellent.
It is an obsolete part but you can probably find it on the internet. If not, let me know and I may be able to help.
Neil
Really nice to hear from you.
Thanks for the info on that other chip. I will
definitely put it on the list. I did some
checking a while ago and it is on the net
(somewhere.)
It's going to take me a long time to do this.
But, Carl's good work aside, I have always
wanted to figure out a how to make a
practical DSB transmitter for 13.560 MHz.
So we'll just take it a step at a time and
see what happens. I believe your chip
puts out more power than the NE602,
so maybe your chip could be modulated
and then go right to an output network
and then to an antenna.
I really like the 13.560 transmitter I have
now, it's good for yardcasting.
Anyway, we'll see where it goes. Life is
really in the way right now, but I am
trying to get around that. Thanks again and
Best Wishes,
bruce, MICRO1690/1700
Hi Guys! I'm back after a LONG absence...just posted a rather large note on the "Pt. 15 SW" forum, but on second thought, maybe I should have put it here. Seems to be more activity on this thread since the one from '09 finally stopped.
Anyway, I have an idea for getting on the air very quickly with an already proven transmitter. It might not be a very good idea, but it is an idea, and I'd like the group to take a look at it. I'm getting itchy to give this Pt. 15 SW thing a go, but I don't know a screw driver from log-nosed pliers. Please check out my rambling on the other forum and comment if you like. I may be completely nuts but it sure is fun!
Ron Kocher - Palm Coast, FL