Measuring SWR

If you want to just measure SWR, then you don’t need to measure RF power meter, then you can use a cheap meter and get adequate results. SWR only is only a relative measurement comparing power going out and power coming back. Given this is does not matter if the frequency response of the RF detectors in the meter are good or bad. Only the forward and reflected sensors need to be equal. If they are equally bad it will work, if they are equally good it will work. The main thing is that they are equal and this is usually the case. This type of meter will work fine for SWR only measurements.

low cost swr rf power meter for 88-108 mhz

Measuring RF Power

If you want to measure RF Power at 88 – 108 and SWR, then you cannot use cheap meters. If you need power sensors that have a flat and uniform response over the frequency range you are measuring. Cheap meters are available with the RF power function, but they will not indicate the correct power. You need to use something like this.

good quality rf power meter and swr meter for 88 108 mhz

Aareff RF Power

All our 100W transmitters and higher in power have a built in meter. On the front panel there’s a forward and reflected switch which allows you to measure the power actually going out to the antenna and if any is being reflected. You don’t need to use an external meter, but you can if you want. If there’s reflected power of between 10 and 15% of the full power, then there’s probably a problem with the connectors, or maybe the screen or ground on the coax where it enters the connector. It’s also possible the antenna has gone off tune a little due to the weather taking it’s toll. With our transmitters if the reflected power is between 15 and 25%, it usually means the cable or antenna somewhere in the line is completely open circuit, basically the signal disconnected somewhere or the exact opposite the signal is being shorted completely to ground.

By Paul Hollings
https://aareff.com/paul-hollings.htm

Mono, MPX, Stereo, Compression, Limiting, Processor, RDS. Which one do I use? Which one do I need?

By Yoneli J
https://aareff.com/yoneli-jimenez.htm

FM Transmitter Mono/MPX Version.

1wpllb-aareff-back

Stations with more engineering experience may use this version, this is because it does not include limiting or stereo coder circuitry. The audio limiting for this version must be externally provided and in accordance with the recommendations of http://www.aareff.com/ETR132.pdf. This version is typically used with external multi band processors, stereo generators and RDS generators such as the brands Orban or Inovonics. Not recommended for novice stations or beginners.

FM Transmitter Stereo Version.

This is similar to the Mono/MPX version except it is stereo and RDS cannot be used with this. Again stations with more engineering experience may use this version, this is because it does not include audio limiting. Again the audio limiting for this version must be externally provided and in accordance with the recommendations of http://www.aareff.com/ETR132.pdf. This version is typically used with external multi band processors and stereo generators such as the brands Orban or Inovonics. Not recommended for novice stations or beginners.

FM Transmitter Stereo Version with Audio Compression and Limiting.

1WPLLSL5

Most small radio stations and beginners will use this version, this is because it includes audio processing circuitry and suitable limiting to keep the transmitter in compliance with the maximum bandwidth permitted by the international regulations. There is also access to the MPX in and out on the back panel which allows all known RDS units to be connected. Novice stations with limited experience of FM broadcasting transmitters should purchase this version.

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.

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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