Ramsey Electronics Phone Patch Mixer Kit PPM3 Especificaciones descargar pdf (Pagina 29)

Chapter 4 should only be considered as reference points. Please check out systems and prices in

your own area since they can vary a lot worldwide.

Many transmitter companies also manufacture FM Broadcasting antennas, while others only

produce antennas. And some companies manufacture both antennas and masts, while some only

make masts. When we use the word “masts” we talk about fixed masts and pump-up mast from 5 to

40 metres. Above this height, we use the term “towers”.

Except for installation of smaller mast systems it is a must to consult professional contractors when

erecting towers for FM Broadcast systems. In most countries it is even compulsory only to use

authorised or licensed companies. A professional installation is often also a precondition if you

want to out an insurance policy on the equipment – and this is highly recommended because bad

weather such as wind, ice and lightening can seriously damage the transmission equipment.

The topography of your landscape has a big influence on the reception of the transmitted signal, and

this is another reason for checking with transmission experts. Instead of building very tall towers,

which can cost fortunes, it might be abetter idea to use several smaller transmitters, which re-

transmit the signal from main transmitter and carries it over mountains and other obstacles.

If you only operate with a small mast and want to install the equipment yourself, it is extremely

important to follow the instructions carefully. And most important: tape all your outdoor plugs and

connections with special bonding tape to make them watertight. Only approved tape delivered for

this purpose must be used. Saving 10 US$ on tape can cost you thousands of dollars in ruined

equipment. With regards to configuring antenna design and patterns you may get some help from

software supplied by some antenna manufacturers such as Itel www.itelcast.com.

3.9 Link Systems

Most small radio stations have the transmitting tower just next to the radio studio. In some cases,

however, the studios can be in a town in a valley and the transmission tower is placed on a

mountain ridge 30 km away in order to give the best coverage. To get the signal from the studio site

to the transmitting site one can use an FM link system, which consists of a small FM Transmitter

situated at the studio site and a FM Receiver, situated at the Transmitter site. This system links the

two sites together and therefore it is called a “Link system”. Normally it operates on frequencies

outside the public FM band 88MHz-108MHz. Typically in the 450MHz band.

Today some companies manufacture digital link systems carrying several channels, and the another

trend is to use microwave digital link systems. The next technology for link systems will most

probably be TCP/IP PC net protocols and wireless Internet in point- to point transmission. This last

system will bring cost considerably down.

In our OB mobile Recording system we also use FM Link systems to be able to reach back home to

the Radio Station from a remote area. With a 12 Metre pump-up mast, a directional antenna and a

25-watt transmitter one should have a range of up to 40 km providing that there is line-of-sight or at

least no major obstacles between the OB site and the Radio station. If more range is needed, it is

possible to place a re-transmission unit in a high tower and reach the radio station via this middle

point.

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Ramsey Electronics Phone Patch Mixer Kit PPM3 Especificaciones Pagina 29