HFU HF Underground

Loggings => FM Free Radio => Topic started by: kopper on January 17, 2018, 1412 UTC

Title: Identifying Emergency Bands
Post by: kopper on January 17, 2018, 1412 UTC
Greetings! Glad to be here. First post. I'm considering purchasing this transmitter from Amazon. Any thoughts/experience/issues/recommendations?

https://smile.amazon.com/dp/B01D44EP4K/ref=cm_sw_r_tw_dp_U_x_g3SxAbNAB4HC4

I have identified four potential frequencies in my area that have empty channels on either side. Am leaning toward either 91.1 or 99.9. Question: How do I know if any of these are already being used by any emergency services (EMS, ambulance, etc.)?

Thanks.
Title: Re: Identifying Emergency Bands
Post by: Σ on January 17, 2018, 1457 UTC
Public safety users don't operate on those frequencies but licensed FM broadcasters do. Legal issues aside with that device finding a vacant frequency to reduce potential interference no matter what power output level you use is good operating practice.

Here is a handy resource that can help identify potential vacant frequencies in your area:

https://radio-locator.com/cgi-bin/vacant
Title: Re: Identifying Emergency Bands
Post by: Strange Beacons on January 17, 2018, 1518 UTC
Greetings! Glad to be here. First post. I'm considering purchasing this transmitter from Amazon. Any thoughts/experience/issues/recommendations?

https://smile.amazon.com/dp/B01D44EP4K/ref=cm_sw_r_tw_dp_U_x_g3SxAbNAB4HC4

I have identified four potential frequencies in my area that have empty channels on either side. Am leaning toward either 91.1 or 99.9. Question: How do I know if any of these are already being used by any emergency services (EMS, ambulance, etc.)?

Thanks.

As with any plan to transmit, you should spend time monitoring the frequencies you are interested in. Keep a log of dates and times of anything heard. Try to vary your own transmission dates and times so as to not be predictable (yes, that goes against the idea of getting any kind of "following" but makes you less vulnerable to anyone seeking to triangulate your position). Bottom line is cause no willful interference, keep it as clean as possible (no foul language, political or religious rants, etc) and chances are you'll be appreciated and not hunted. Good luck.
Title: Re: Identifying Emergency Bands
Post by: kopper on January 17, 2018, 1924 UTC
Public safety users don't operate on those frequencies but licensed FM broadcasters do. Legal issues aside with that device finding a vacant frequency to reduce potential interference no matter what power output level you use is good operating practice.

Here is a handy resource that can help identify potential vacant frequencies in your area:

https://radio-locator.com/cgi-bin/vacant

Thanks! That's actually what I used. There is a station 50 miles away on one of the frequencies; should probably avoid that one. The other has a station over 200 miles away. I could hear it fairly clearly in my car, but it does not specifically serve my area. I was also considering 87.7 since we have no channel 6 in the area but there is a community radio station operating at 88.1.
Title: Re: Identifying Emergency Bands
Post by: ThElectriCat on March 06, 2018, 0038 UTC
Its good to see FM pirates who do there homework first, Good on ya.
Fm can carry farther than many people think. One of the broadcast stations I maintain only puts out 400 watts, yet I can hear it full quieting about 80 miles away. this result is unusually good, but it can happen.
with low power (less than 100 watts) and a 1/4 wave vertical or 1/2 wave dipole, you are unlikely to cause problems to a station 50 miles away, but I would strongly suggest you record your first show so you can drive around between your station and the licensed one while it is playing. the studio at the radio station wont hear you at all, but some of their listeners might, especially if they're close to you and farther from the station.  and picket fencing between your station will generate calls to the studio.

the FCC may be a toothless old dog, but paying spectrum users are not. a broadcast station will report you if you annoy them.

I suggest using a mild directional antenna and putting the nulls in like with the legal broadcaster.

and of course, I "cannot condone Illegal Broadcasting", but wish you the best of luck in your endeavors.

P.S make friends with your local broadcast engineer if you can, many of us arent against pirate radio at all, as long as it dosent hurt our stations, just tread carefully.
Title: Re: Identifying Emergency Bands
Post by: Tim Bucknall on August 27, 2018, 0858 UTC
Let me know how you get on with that tx,  Particularly spurious radiation.
I only need half a watt but LP txs tend to be poor quality
Looks like i should get a bigger tx and turn it down
Title: Re: Identifying Emergency Bands
Post by: Tim Bucknall on August 28, 2018, 1924 UTC
Fyi:
Half a watt into a directional vertical log periodic on a totally clear channel entirely covered a town of 100,000 people on undulating topography with minimal overspill. I was  lucky to be able to broadcast from the extreme
Western edge of the town so beaming east covered the
Whole town, including the town centre 1.5 miles away that sits in a dip.

I may try a channel that has a strong out of area tx to limit overspill even more

But in the USA you dont have to worry about stuff like that because a set up like I described wouldn't get you in trouble.


A guy in the next town ran 3 frequencies  24/7 at low power for years with no trouble, he's probably still doing it but the band is  now so full I can't hear him