- January 7, 2019 at 3:45 pm #108587
Wasn’t someone at one time experimenting with part15 shortwave? How’s that work? How far can it go?January 7, 2019 at 5:54 pm #108591
We Made History At the Time
Several years ago a bunch of members designed a part 15 compliant shortwave transmitter that we named “The Big Talker”, especially designed for 15.360 MHz or was it 13.560 MHz (?)
Contributors included Radio8Z, PhilB, MICRO1700, Ermi Roos and probably other names I am forgetting.
The final design produced two designs, the mid-stage buffer having two possible circuits.
I had mine operating for a long time and the parts are now on the workbench waiting to be installed in a case.
If you are in a circuit-building mood I can link you to our diagrams.January 8, 2019 at 10:56 am #108594
Hmmm.. answered this last night at about 1am, little later noticed my comment wasn’t here so answered again about 2am… My comment is not here again!
AAaarrrg.. ok.. will try again…
Not ready to attempt to build anything yet, but curious how it sounded and how far the signal would travel. Did you do a show about it? Any recordings of the shortwave broadcast on the receiving end?January 8, 2019 at 11:09 am #108597
I definitely will re-link the Big Talker documentation because it includes a paper from PhilB (inventor of the AMT3000/5000 transmitters) explaining why at the allowed power level a vertical antenna would provide the best result and I think he also estimated the probable distance under normal conditions.
While visiting the Hobby Radio Super Center, click the Low Power Radio Resources and in the column under “Transmitters” scroll down until it says “Big Talker”. That’s where it will be after I re-link.
At the time I was running mine I had a dipole indoor 1/4-wave antenna but did not attempt to determine the range even though I looked around for a shortwave car radio but didn’t find one.
Now that we have two people experiencing submitted posts disappearing it is time for the website administrator to troubleshoot the problem.January 8, 2019 at 11:15 am #108598
How It Sounded
The Big Talker was Amplitude Modulated and sounded great!January 8, 2019 at 12:09 pm #108600
Oooooo… it was amplitude modulated? Cool! I want to be able to that. Where can I get an amplitude modulator from?January 8, 2019 at 12:11 pm #108601
All the requested links have been made.
Everything asked for is now provided.
The KDX web archives are a maze and labyrinth and I am lost in here and can’t find the exit.January 8, 2019 at 12:14 pm #108602
The question: “Where can I get an amplitude modulator from?”
A modulation section is built into the Big Talker Shortwave Transmitter.
It took weeks and maybe months to find a perfectly efficient modulation transformer but we spared nothing and deserve many rewards.January 16, 2019 at 3:44 pm #108829
This 1990 Monitoring Times issue relates to shortwave part 15 broadcasting -I think.. if that’s the same thing as “Medfer”.. Anyway, you can read/download the entire 4 page article (actually it’s the entire issue) from https://archive.org/details/MonitoringTimesMarch1990/page/n9?q=%22part+15%22January 16, 2019 at 4:50 pm #108830MarkModerator
Total posts : 564
This Can’t be true. 100mW with a 10 ft antenna can get 500 miles??
Only thing that’s true is the last statement about Canada…..no restriction on antenna length.January 16, 2019 at 6:59 pm #108834ThelegacyParticipant
Total posts : 291
Part 15 AM can skywave
There has been reports of legal part 15 installs going many miles out as some DXers has reported.
I’d really like to know about SW.January 17, 2019 at 9:56 am #108841
TheLegacy knows: “There has been reports of legal part 15 installs going many miles out as some DXers has reported.”
In all these years I have never heard those “reports”.
Can you link some of them?January 17, 2019 at 11:57 am #108846AMRadiolegendParticipant
Total posts : 323
Many miles? Is that greater than 2? Also, the ISM Band AM SW transmitters are more likely to be heard 500 to 1,000 miles away during daylight hours utilizing a resonant horizontal dipole 20 feet above ground or higher.January 17, 2019 at 12:04 pm #108848
I don’t think Legacy was referring to the broadcast bands but in other frequencies like (as reported in the above article) broadcasting part 15 at 1619.5khz was receivable 500 miles away.January 17, 2019 at 12:10 pm #108849
Wait a minute… now I’m confused. That can’t be right, but it’s what it said.
Edit.. oh, sorry, that’s was exactly Marks point..
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