Hello Georg:
I agree with Ermi. I am just a small contributor
to this site. We don't know what happened.
I think you are very good with RF electronics.
Good Luck To You
Bruce, MICRO1690/1700
Connecticut
Georg N,
From what I was able to see, you were only being helpful. Maybe one of the site administrators will explain what is going on. I seriously doubt that you are stupid. One does not become an M.D. by being stupid.
To all,
thank you for your nice and warm comments. So I will try again to give everyone the opportunity to share my hobby.
Information to the site administrator:
Sorry, I did not want to produce any misunderstandings.
Listen, this particular site i am referring to contains nothing else but hobby. There is nothing to sell or buy.
It contains only free download links for hobby purpose.
The downloads contain nothing but hobby. O.k.?
To all who are interested in my hobby 13560 kHz oscillator:
What I intended to construct for my hobby: An 13560 kHz oscillator which is rather constant in frequency and which produces low second and third harmonics. The next step will be a driver stage and a power stage which can be modulated by AM. There is something in progress, but it is too early to give it away.
I am very interested to hear your comments.
Greetings from Germany
Georg N.
I checked the records and I do see that your first ID is blocked, the better way to deal with that is to write and get your ID unblocked rather than creating a new ID.
This site gets quite a few spam posts each week, usually something like "That antenna is a great idea - more good ideas here - LINK" and the link is spam. It's possible someone clicked "Report to Mollom" because your link seemed to go to a medical rather than radio information site.
The request for emails in your earlier post is also a red flag, as spammers will also post "Great radio ideas - send me an email" and anyone who does that gets spammed, too.
All that being said, your radio information link is great and I've repeated it below. Thank you very much for extending the courtesy of providing that information in English.
Now I'm breathing a sigh of relief.
Thank you again. I'm going to switch on my soldering iron right now.
Georg N.
Dear Dr. Georg N.
I also breathe relief now that the uproar is explained and sorted out.
One thing in particular strikes me about your oscillator circuit that makes it different than the Pixie2 circuit that opened this forum. In your circuit the 2nd & 3rd harmonic are filtered at the outset, at stage 1. In the Pixie2 the harmonic filtering is done at the final output.
I believe I prefer your approach and look forward to the next diagrams from you.
Dear Carl,
up to now I did not manage to read all the comments (and I must confess that I did not find the schematics of the pixie).
The more I learn about shortwave RF electronics the less I understand or even know. What I think is: (1) distortions come from the crystal itself, because the quartz does not do what you want it to do, and mechanical oscillations inside the crystal are never simple and easy. (2) distortions come from the fact that you need strong feedbach at the oscillator stage in order to get stable oscillations. On the other hand, strong feedback drives the transistor into clipping the signal. (3) distortions come from highly efficiant power stages which are operated at a zero quiescent current.
What I think the consequences are: (1) put in filters to suppress harmonics at each stage (2) do not use too low a quiescent current (3) use an oscilloscope because it shows what you get.
(Sorry, I am very short because I am on the way to work)
Yours, Georg N.
Hi Carl,
thank you for your nice comment. By looking at the schematics, I think Pixie 2 is very good. Of course, it is famous. There are only few parts and I think the coils are not critical. - There is another big difference (apart of some similarities) to my approach: Pixie produces much more power in only two stages. Output of my oscillator is only Mikrowatt (µW). I need much more material to achieve much less Power.
Now there is the first driver stage on my radio web page (Its output is only less than 5 Milliwatts).
Yours, Georg N.
Dear Dr. Georg N.:
As you have noticed we in the U.S. are limited as to our radiated power on 13.56mHz, and so your gradual buildup of power may be our better solution.
Some members have talked about possibly having to attenuate the power of the Pixie2 in the event it produces too much output. As of now no one has proven where the Pixie2 actually stands in regard to its output power.
What kind of power regulations govern you in Germany?
First of all, Georg, I looked at your web
page and your circuit with the new buffer
stage looks really good. Right now, though
I have another circuit that I am working
on. It is the Pixie circuit. I have very poor
eyesight, so for now I will stay with the
circuit I have, but in the future I can try
to build your transmitter. (I work very
slowly.)
I have a question for everybody. This is
very basic, but it is hard for me to look it
up so I will just ask it.
My Pixie transmitter oscillator is actually
running on exactly 13.561 MHz, according
to my frequency counter. If possible, I
would like to stretch the frequency down
to 13.560. Do you guys have any ideas
where I should put the caps on the crystal
to do that? Series? Parallel? Both? I don't
know the specs on the crystal, but I can
probably find out if that is necessary.
Carl, unlike your transmitter, which has high
fidelity, my transmitter sounds more like a
telephone. I think the response is topping
off at about 3 or 4 kHz. So actually, if I
had to transmit on 13.561 for now, my
sidebands would not be out of the 13 MHz
part 15 allocation.
Thanks a lot guys! I am still out here plugging
away.
Bruce,MICRO1690/1700
MICRO1700
Unlike you I have not measured my frequency accuracy, but would like to have the ability to fine-tune if needed. I would only be guessing if I attempted to solve the problem, but the good thing is there will be members with very experienced answers.
The truth is, this whole process goes slow because of the detail we strive to achieve.
Bruce,
How many digits does your frequency counter display? The reason I ask is that there is an inherent uncertainty of +/- 1 digit in digital meters. If your counter literally reads 13.561 then the frequency could be in the range 13.560 to 13.562 not counting possible time base errors.
If possible, change the time gate to 10 seconds which will improve the resolution 10X. Don't worry if it overflows since you already know the left most digit.
To lower the frequency place a trimmer cap. in parallel with the crystal. Something in the range of 15 or 25 pF maximum capacitance should work. Too much capacitance usually causes the oscillator to stop working.
Neil
Hi Neil and Carl and Everybody:
Neil, thanks for the info on where the cap should go.
My counter actually was reading 13.5610. I should
have mentioned that, but as you can see, it does
mean that I'm exactly 1 KC high. I hope it can
be stretched down to 13.5600. I know you can
only take it so far.
Thanks so much. I have more comments to follow.
Bruce, MICRO1690/1700
Hi Everybody:
I have recently come across some schematics
for some very simple DSB transmitting circuits.
I think I'm going to go in a different direction
with this eventually.
Since my target listener a mile away is using a
good HF receiving set-up, I am now thinking of
trying DSB. It is a lot simpler than trying to
build an SSB transmitter and I think there is
hardly any practical difference between the two.
I remember a shortwave
broadcaster that ran SSB years ago. It was Radio
For Peace International. Music on SSB was a little
weird, but that's all part of the fun. I used to listen
to a show called "World of Radio," by a famous SWL/AM/FM
dxer known as Glenn Hauser. I'm sure his name is
familiar to many people who are reading this. I
haven't listened to him in many years, but I recall
that his show has/had a beginning theme song, and
if I tuned my ICOM R-70 just right, the music sounded
OK on SSB. Talk progamming would be no problem.
So the idea is to feed a balanced modulator with
the RF carrier on one side and the audio on the
other side. The DSB output would then be fed
to a linear amp and the appropriate filter. The
listener could tune into either sideband, it wouldn't
make any difference. But I think with this, a readable
signal on 13 MHz Part 15 would have a chance to
go a lot farther if it was DSB instead of AM. In
addition, the balanced modulator could be unbalanced
with a simple adjustment, and reduced carrier AM could
be transmitted.
Since my target listener, who is my friend a mile away,
has a good HF receiving set-up, I think he would have
no problem hearing this. He has heard my AM signal
during the day on 1690 on his car radio in his driveway
with no problem, but reception in his house is very
problematic, because of all the RF noise in there.
So, I'm going to look into this more, so my friend can
hear my station easily a mile away. If anybody has
any comments on 13 MHz DSB transmission, please
let me know what you have.
Thanks to all
Bruce, MICRO1690/1700
Dear Carl Blare,
thank you for your interesting questions; about restrictions: I plan to ask someone in the authority (in Germany they are called RegTP which means authority for regulation in telecommunication and mail).
About measurement of frequency: Do you have any shortwave-PLL-receiver with BFO? If the digital display is accurate enough: switch on USB, put the BFO-fine-tuning to zero (middle position), and turn the frequency tuning dial until the interference you hear goes to zero beat. Then you can read the frequency of your transmitter on the display of the radio. But I'm sure that's nothing new for you.
About low power: How can an amateur measure that 10 Millivolts per meter (or whatever) field strength? Grundig says, the s-meter of the satellite 3400 (built in the 80's ) is calibrated, and so I can measure Mikrovolts or Millivolts at the antenna connector. At least I may get an approximation. But: which RX antenna should I use to know the field strength? I guess it should be a dipole. But which length? Lambda / 2 or Lambda / 4 ? Which antenna hight? Which polarisation? And how do you handle such long antenna? Everything depends on that.
Dear Neil,
fine tuning of quartz frequency: I fully aggree with you. An adjustable capacitor (25...100 pF) in series can pull the frequency higher (the lower the capacity, the higher the frequency). An adjustable capacitor (3...30 pF) parallel to the quartz can pull the frequency lower (the larger the capacity, the lower the frequency).
Dear Bruce, Micro 1700,
thank you for your nice comment. With that circuit I am just at the beginning. If you like to look again onto my radio web page: driver stages 1+2 are out now. I really don't know where this development will go. Although I did not try to build DSB or SSB circuits, I would be interested to see such circuits.
Yours, Georg N.