Not everyone is able to have an outdoor AM transmitting antenna, and we soon find that indoor antennas result in a lot of loud buzzing on the radio along with hearing your signal. What's going on with that?
What I think might be happening is that AC electric wiring in the walls is picking up and re-transmitting your signal, with the 60 Hz powerline frequency mixing and modulating on top of your signal.
Can this somehow be avoided? Maybe large toroids placed strategically on the electric wiring or extra large capacitors and chokes to neutralize signals in the wires above, let's say, 100kHz.
Your thoughts and suggestions.
You are right that not everyone can have access to an outdoor set up and I have the Procaster as I assume you do and have used it indoors and even made that in the cabinet ground I posted. I had no humming except very little when the radio was turned a certain way. Outside clean as can be. First of all disconnect the 3 piece aluminum outdoor antenna and use a 104" wire with an alligator clip to attach it to the antenna lug. Tape it to a wall or window and try different shapes as this affects the tuning peak. The power supply/12 volt adaptor is most of this problem of buzzing and humming. Not all are created equal. Has to be properly filtered. The computer brick style ones the monitors use are best. You can go to Mouser(on line) and get Triad brand. They are good too. To see if any interference you are getting is the power supply you can run this from a 12 volt battery like two 6 volt lantern batteries in series and just rig a connector cut from an adaptor connected to the battery terminals and to the studio part. Make sure to not connect wrong polarity!! Tim did his testing outside with the different transmitters by doing this from a battery.
I could try different power supplies until I found one that worked.
Also you can get a good noise filter like Isobar made by Tripp Lite. Won't let me paste it here but go to Amazon and search Isobar protection, may help.
Every part 15 station operator sooner or later has the experience of solving a technical problem by an accidental discovery. The loud buzzing I was hearing at some locations in the house and near the powerline outside was noticeably gone today. Naturally I thought back a few hours remembering what might have caused the change, and as it turns out I'd been in the basement and discovered a light that had been left turned on for days. It was a first generation LED bulb and evidently generates a lot of RF hash.
AM working OK now? Get rid of that bulb and get a newer one. The worst is the florescent ones.
It's so good. Yes, the Procaster AM signal is now clean and sweet. This is the second lightbulb that has shown up on spectrum analyzers. The other one totally blitzed the longwave band below regular AM. As part 15 station operators we've got to watch the radio spectrum to make sure we aren't the one messing it up.
You see about the bulbs? What about the FCC rule about not causing interference?
A way to transmit on am without a complex outdoor antenna .... Hang a 10 foot thin wire out the window . I've done this while traveling, a ND decent results. ..4.25 miles using a talking house transmitter using the built in tuner . There're many ways to hide antennas too , especially wire antennas. A wire antenna can be painted to match the color of the building or be put in a bush .
I have been posting about this for a long time on how to get good results from indoors with a Procaster and my self devised in the cabinet "ground". The antenna doesn't even have to be outdoors if it's a window or even a wooden or brick wall. The only way it wouldn't work indoors is if you are in a metal building or house with aluminum siding. I got a daytime signal for 1/2 a km or more around me from a basement!
Say more. Over in the thread titled "KDX Expansion Plans" member Heavy Metal (formerly Diablo) said he's experimenting with loop antennas. But I want him to say more about it. Are the loops for transmitting? If so, what are you finding out. Do loops transmit well? Is the transmission directional or omni-directional?
And then Part 15 Engineer said he purchased an SSTran AMT5000, but said no word about what kind of antenna he's using. Say more about it. By the way, say hi to Jeff Station 8. I miss the old days when we used to chatter at Team Speak meetings.
I got some metal Slinky Toys to try as antennas, but what's the difference between a Slinky antenna and a Helical antenna, or a coil, or an inductor?