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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Why use your limiters? the bigger nice looking 19 inch rack limiters from Behringer and other similar brands are the same price?

For FM broadcasting the attack has to be very fast at all audio frequencies, audio above 15KHz should be cut and pre-emphasis has to be applied before limiting.The commercial 19 inch rack mount type limiters, compressors and audio processors that are for bands, discos and recording studios don’t do this.

Our limiters do not use any digital sampling, they are high quality, low distortion, low noise and analogue design, perfect for FM transmitters.

Our limiters start to cut off sharply at around 14 KHz using a Salem and Key active filter. The commercial 19 inch rack mount type work up to 20KHz and way beyond, in the applications they are designed for this is okay and there’s no reason to cut the frequency above 15 KHz. They are not designed for FM transmitters
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A radio repeater is a combination of a radio receiver and a radio transmitter that receives a weak or low-level signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation.

It is an automatic radio-relay station, usually located on a mountain top, tall building, or radio tower. It allows communication between two or more bases, mobile or portable stations that are unable to communicate directly with each other due to distance or obstructions between them.

The repeater receives on one radio frequency (the “input” frequency), demodulates the signal, and simultaneously re-transmits the information on its “output” frequency.
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