About how far do you think a 500 mw FM transmitter would effectively broadcast?

that`s impossible to determine without knowing the frequency, antenna specs, and the sort of area you`ll broadcast from.

 

also Much of it depends on the receiver also!

 

I`ve transmit half way around the world on less than 500mw

I`ve transmit half way around the world on less than 500mw

 

How did you find that out ?

 

Nevermore, as YT said it's impossible to work out until you set it up, due to location. A friend of mine (this was many years ago) used to record at home, and then stick a DAT player in a tree with a mini-transmitter...you could pick up signals on the south downs (higher altitude) but it was nonexistent in town.

 

Out of interest, is this for audio or video ?

I was using a "Matchbox transmitter" it was a cct I found in a copy of Practical Electronics magazine back in the mid 80`s.

 

it was a Morse code Shortwave transmitter and literally fit inside a matchbox

I and Friend of mine had a 2 way "chat" with a Lady in Australia, and even got a QSL card each

even though I didn`t have a HAm license or official call sign.

This is FM, not shortwave. (I assume he meant FM band, not FM for modulation only.)

The particular one I'm looking at can go from 87-107.9 mhz. As for the antenna, the transmitter is labled:

Antenna output impedance: 50 OM

Antenna Connector: BNC type

(I'm quite new to all things radio, and am just diving right in, so I'm a bit clueless.)

I'd be broadcasting from a suburb at about sea level.

you should be able to do a couple of Kms quite easily if you set it up properly.

I personally would opt for a straight forward Dipole mounted as high as possible and away from any structures nearby. the loading impedance is 50 Ohms but you`ll still need to use 75 ohm coax (TV coax), and not the RG8 or RG58 50ohm coax.

rem with the dipole it must be tuned to the freq that you transmit on to keep the SWR as low as possible (Standing Wave Ratio).

this is pretty easy to work out also, aim for a Half wave dipole also (it`ll be around the 5 foot mark in length).

take 300 and divide it by the freq you transmit on, then divide that number by 2, that will tell you how long the radiating element will have to be for a halfwave dipole in Metres.

 

a few Kms is quite Doable

you can also make decent booster amplifiers for the reciever, at which point the distance is very much dependant on the radio noise in the area.

if you go out to where they're going to build the square kilometre array, you'd get far better reception than under a tesla coil for example.

Thanks!