So I wanted to share my idea, and the gear I've found to maybe get a little feedback.
First of all, I want to set up and broadcast in essentially the downtown of a major US city. Is this a terrible idea, just in terms of putting my self at risk? I'm perched at a high point overlooking a large portion of a major US city, and I'd love to broadcast, but worried with that amount of potential exposure, it could be too much of a risk. Thoughts?
I was looking at these FMuser 15w transmitters (i'd see some years-old reviews on here, saying they'd had some issues, but nothing as of recent):
Are these machines reliable? Can you really get the power you want out of them? Additionally, One review mentions that the pre-emphasis is 50uS, when it should be 75uS. This is my first time researching what that means, but it seems like with a basic EQ, you could just bump up the high end to compensate? Anyway, if that transmitter isn't a good option, what is recommended?
I'm not super familiar with antenna types. Is a ground plane the type I'd want for this sort of job?
Ok, and now for the idea itself.
Basically, I want to set up a remote station, where I would have the antenna, transmitter, and an ipod (playing a looped recording) all on a timer. At a specific time in the day, the timer would kick on, powering the transmitter, sending my recording out for a specific duration, then the timer would kill the power. I'd essentially be broadcasting for a period of time in the night, every night. I'm new to this, but if its possible to have the transmitter always power on to the same frequency, then that seems like it would work right?
Any thoughts and suggestions are appreciated. Thanks!
Post by HighMountainRadio on Mar 18, 2018 8:04:02 GMT -6
Greetings From High Mountain Radio !
I just saw your post here and although I realize I am late to the show here, I thought I would make recommendations and answer your questions that you posed anyway. Perhaps if this information is now obsolete to you it may still assist others who are contemplating setting up a similar station.
First, broadcasting in any major city is much riskier than if you were out in the boondocks. That being said, since you will only be broadcasting at night, depending on what time of night, perhaps a little less risky than if you were on the air in the daytime. Your idea of operating your transmitter on autopilot would work just fine depending on what transmitter you may be thinking of using. The FMUser.org Model FU-15A is an excellent choice, however, you can purchase the EXACT same model of transmitter, simply marketed in a different enclosure, as the Generic Model ST-15B FM broadcast transmitter. It has excellent audio quality and can be purchased set to 75us pre-emphasis, although this must be requested at the time of purchase. Any reputable vendor can arrange this. The best part is that you can purchase the generic ST-15B for as little as $58.00 on EBay from many resellers ! FMUser.org is selling the EXACT SAME transmitter in a bit more colorful and fancy enclosure for $109.00. The generic ST-15B comes in three versions, V1, V2 and V3. The difference between them is the power setting feature. The V1 version is 15 watts only. The V2 version can be switched between 5 or 15 watts output. The V3 version is also 15 watts only, not switchable. From my observation, since I have two ST-15B transmitters, you most likely will not get 15 watts output in high power, it will be more like 10 watts in HIGH power and more like 3-4 watts in LOW power mode. I did not find this to be a major issue since I am using my unit at 10 watts output and using a 3 db attenuator to reduce my RF drive level to a safe level that drives my homebrew 80 watt RF power amplifier.
The Ground Plane antenna is an excellent choice ! It will serve your needs well ! Be certain to use the highest quality coaxial cable as you can afford on your budget, I highly recommend using RG-9913, about $1.00 per foot but well worth the money ! it has a loss figure of 1.4 db per 100 feet of length, pretty much the lowest loss coaxial cable you can buy. I also HIGHLY recommend using a 'balun' at your antenna feed point to ensure that your coaxial cable will not radiate along it's length, a highly undesirable issue that will cause an unsafely high VSWR (reflected power) back to your transmitter and likely may cause harmful interference to nearby RF and audio equipment and landline telephones. You can easily fabricate an inexpensive 'coaxial balun' which consists of 6 turns of coaxial cable coiled one turn adjacent to the previous loop formed into a 6 inch circle. I cut small pieces of flat, thin wood shims for use in aiding to hold the loops together correctly and simply wrapped electrical tape around the formed loops and wood shims to help keep the intended form. You can simply form the balun right into the coaxial cable feedline right before the antenna feed point. Leave enough cable where the feedline meets the antenna so that you can form the 6 inch loop of cable, thus integrating the balun right into your feedline ! See included pictures of my homebrew balun to get an idea of how to fabricate one. I have also included pictures of the generic ST-15B transmitter.
The generic ST-15B transmitter will retain all settings once set and powered down so it would work perfectly with a timer to switch it on and off at the required times. I'd enjoy hearing back from you on your exploits to see how things are working out for you !
Keep On Rockin' In The Free World ! 73... Spooky...
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