https://www.aareff.com/en/250w-erp-fm-transmitter-system.htm

By Michael Campos
https://aareff.com/michael-campos.htm

Community radio also known as LPFM in the USA which stands for LOW POWER FM was created to provide a non expensive method for non profit groups to get on the air operating anywhere from 1w – 100w. This attempts to bring humanity together, induce creativity in individuals and transform communities by having their own people RUN and PRODUCE their own programs. This gives sufficient time to elaborate programs which bring interest to the community. One of the reasons for this sufficient time is that generally community radios are legally PROHIBITED or RESTRICTED to play any sort of advertisements opposed to commercial radio.

To the best of our knowledge the first known community radio was introduced in 1940 in Bolivia during a labor strike, since then it’s become an essential tool for communities to fulfilling the urge, the desire for communication and self expression.

Community Radio in some countries is not protected from interference that may be received, unlike commercial radio. Also it’s sponsored by individuals and business that believe in the concept of giving a voice to the rarely heard while giving us the freedom of speech thought and expression.

On the other hand commercial radio is based on business on the practice of airing radio advertisements for profit. Commercial radios mostly owned by private corporates and are known for playing high quantities of copyright music with a high ratio of advertisements cutting short the time for community programs and local issues.

Things You Didn’t Know About Commercial Radio

1.In most stations DJ’s don’t pick the music, the management do this.
2.Your production must be very professional or it won’t be played.
3.Buying advertisements and trading publications is not required but helpful.
4.It’s not about if your music is good or not, it’s about ratings.

In conclusion, community radio was created to give people of the community an opportunity to express themselves in a with truth and honesty in way that cannot be done with commercial radio.

This is the 5/8 FM antenna, one of our best products with over 15 years of sales. Over the years this antenna has had some small adjustments in its design but has retained it’s reliable quality made structure.

The materials we use to make this ultra reliable structure include Teflon, aluminium and brass. The Teflon carries the intense RF signal through the FM antenna without melting its base. This allows the 5/8 antenna to be used at high power, even a few KW with the 7-16 connector. Inside the aluminium tubes there are brass inserts that provide excellent conductivity between its connecting points.

In order to test the reliability of its build we gave this FM antenna some pretty tough tests. First we gave it a drop test and apart from a couple of scuff marks, the antenna was intact. After that we gave it a bend test to see how far it could bend before it snapped and our results were interesting. We managed to bend the antenna almost a full 30 degrees before we could see the metal begin to loose its structural integrity and then we bent it back and it worked perfectly again.

This year we made some major changes to the 5/8 antenna, the most significant change was providing the customer the facility to ajust the antenna between 88 and 108 MHz. We did this by making the main inductor at the base variable in steps, to put it simpler, this is an aluminium bar that can be moved over six different positions.

Aareff 5/8 FM Antenna

By changing the length and selecting the correct position it is possible to have an SWR of less than 1.1. Another change we made was that we added more telescopic sections to enable the FM antenna to be packed in a box only 60 cm in length. This allows us to send the antenna as a small packet through the postal system and therefore keep the antenna quality high, the delivery cost low and the overall price competitive and good value for money. DHL delivery is available for a small extra cost.

There are many advantages in using this antenna, however there are also a couple of disadvantages. These are shown below.

Advantages:
– Easy to install
– Sits on top of the tower
– True perfect omni-directional radiation pattern
– Light weight, low wind loading

Disadvantages:
– Not good for mounting on side of a tower.
– Narrow frequency range.(Only 2MHz)

To learn more about this antenna, click here: Aareff 5/8 antenna

By Alex Hollings
https://www.aareff.com/alex-hollings.htm

You can have the biggest and the best FM transmitter in the world, but if the power doesn’t get from it to the antenna you may as well turn it off. A transmitter is only as good as the antenna it is connected to. A poorly tuned antenna and antenna cable will send the power back to the transmitter and in worse case cause it to over heat resulting in permanent damage. It’s a bit like driving a car with flat tyres, it will move slowly, but most of the power will be used in chewing the wheel rims to pieces. A well tuned antenna will take all the power put into it and radiated it all into free space. The antenna is effectively a transformer between the transmitters RF electrical current and free space.

The term SWR is used to measure the performance of an antenna.SWR is short for Standing Wave Ratio. An SWR of 1:1 indicates that the antenna is perfectly matched and there’s no reflected power. At the other end of the scale an SWR of 1:Infinity indicates that no power is being absorbed by the antenna and all the transmitter power is being reflected back to the transmitter.

A useful piece of test equipment that measures SWR is an SWR meter. All serious radio stations should have one of these. This connects in line between the transmitter and the antenna and antenna cable. SWR meters have a switch on them usually labeled up as FWD and REF. In the FWD position the meter indicates the forward power traveling on the antenna cable, this is the power going from the transmitter to the antenna. In the REF position the meter indicates the reflected power traveling on the antenna cable, this is the power that has not been absorbed by the antenna returning back to the transmitter. To make an SWR reading the transmitter is switched on, the meter is set to FWD position and the CAL control is turned to make the meter needle point to 100%. The SWR meter is then set to REF position, the reading shown on the meter is the amount of reflected power relative to the forward power.

Significance of the SWR reading.
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