FM Transmitters and RF amplifiers.

[sram]

Just a quick question:

Does all FM Transmitters allow being connected to a power amplifier? Meaning if the transmitter is 300 watts, so instead of buying a new transmitter with more power, you just get an amplifier and hook it to the transmitter and call it a day. In other words, are all transmitters designed to feed their signal into an amplifier to increase its power?


The FM transmitter I have is MIZAR FM transmitter 300 watts.

https://www.google.com/url?sa=t&sou...sg=AFQjCNGd-0MB005JcqUneb76PTPu81XyaQ&cad=rja

 

[Nigel Goodwin]

Just a quick question:

Does all FM Transmitters allow being connected to a power amplifier? Meaning if the transmitter is 300 watts, so instead of buying a new transmitter with more power, you just get an amplifier and hook it to the transmitter and call it a day. In other words, are all transmitters designed to feed their signal into an amplifier to increase its power?


The FM transmitter I have is MIZAR FM transmitter 300 watts.

https://www.google.com/url?sa=t&sou...sg=AFQjCNGd-0MB005JcqUneb76PTPu81XyaQ&cad=rja

All 'real' transmitters and power amplifiers are - they are designed for a standard input and output impedance (either 50 or 75 ohms) - so if you have a 10W transmitter, you simply buy (or build) a 10W to 300W amplifier.

The main concerns are legality, it's likely to be highly illegal unless you have a licence specifically allowing that power and frequency - and 300W on band II would be dead easy to trace.

 

[sram]

Are you saying that the transmitter will have a RF-out port which can directly go to the antenna, and another port which can be connected to RF-in port in an amplifier, and then from the amplifier, a the feeding cable will go to the antenna from the amplifier's RF-out port?

Is it something like this?

Thanks.

 

[Nigel Goodwin]

Are you saying that the transmitter will have a RF-out port which can directly go to the antenna, and another port which can be connected to RF-in port in an amplifier, and then from the amplifier, a the feeding cable will go to the antenna from the amplifier's RF-out port?

Is it something like this?

No, you take the aerial out of the transmitter and plug it in to the output of the amplifier, then you connect a lead from the output of the transmitter to the input of the amplifier.

In fact it's almost certain the transmitter is built that way inside - with a low power transmitter connected to a separate higher power amplifier inside the same box.

 

[sram]

Hmmmm. So, instead of connecting the RF-out of the transmitter directly to the antenna via the feeder cable, you connect it to RF-in of the amplifier using another cable. Then, you connect the RF-out port in the amplifier to the antenna using the feeder. Like this diagram shows:
**broken link removed**

Uploaded with ImageShack.us
Am I right?

 

[Nigel Goodwin]

Yes, as simple as that.

 

[sram]

Okay what but power will the signal fed into the amplifier carry? As you know the output power can be adjusted, so what should be set to? Does it matter if it 10 watts or 300 watts? I'm afraid I will damage something. I'm not sure how the amplification works, but will my 1000 watts amplifier put out 1000 watts regardless of how much input power is fed into it?

This is the amplifier. I got it for free, so I want to take advantage of that.

**broken link removed**

Uploaded with ImageShack.us


**broken link removed**

Uploaded with ImageShack.us

 

[Nigel Goodwin]

You set it to match the input requirements of the power amplifier, and if it's the feed transmitter is not adjustable you would use a suitable attenuator to reduce the power (although you say yours is, so that shouldn't apply).

Generally power amplifiers are fixed gain, but it's certainly possible that there are some which will accept varying powers and adjust themselves accordingly - you need to read the specs on the power amplifier.

 

[trash]

Looks like a nice score for a freebie.
BNC input and DIN output on the back.

Question is where do you intend to use it ?
I don't care about legalities, there are plenty of areas on the planet where authorities don't care until you earn enough money for them to get a cut.

 

[sram]

Legalities is no problem. I didn't get what you mean by : Looks like a nice score for a freebie ????????????

 

[sram]

Okay. I found the specs sheet for that amplifier. Here:

https://www.google.com/url?sa=t&sou...sg=AFQjCNHYXNnjzLZYeU4-C1Tjsdp8lR-icw&cad=rja

It says 0-20 watts. So I'm fine^_^ Right, Nigel?

I appreciate all your help.......thanks, and keep up the outstanding work you are doing here in this super forum.

 

[ronsimpson]

On the power amp; The input connector is not the same as the output connector. Your cable from amp to antenna should be replaced with the larger cable. The antenna may have to be replaced. Check the data on you cable and antenna!

 

[Nigel Goodwin]

Okay. I found the specs sheet for that amplifier. Here:

https://www.google.com/url?sa=t&sou...sg=AFQjCNHYXNnjzLZYeU4-C1Tjsdp8lR-icw&cad=rja

It says 0-20 watts. So I'm fine^_^ Right, Nigel?

I appreciate all your help.......thanks, and keep up the outstanding work you are doing here in this super forum.

Looks like it should be fine.