Need help with FM Radio Transmitter / Amplifier

Thread Starter

Captain Star

Joined Mar 26, 2023
7
So I purchased this : (HanRongDa HDR-831)
HanRongDa HDR-831

It's working great but the practical range is about 15 meters.
I'm looking to upgrade this. The thing is, I know very little about radio frequencies and antennas.

Can something like this work ?
Ebay Amplifier

The device I purchased seems to have a really simplistic antenna, like a single wire.
HanRongDa Antenna
As opposed to let's say a Baofeng UV-5R witch has a more complexe antenna.
Baofeng Antenna

Also if that little amplifier would work, what type of 'antenna' cable do I need, to hook it up to the HanRongDa HDR-831 ?
Thank you !
 

Audioguru again

Joined Oct 21, 2019
5,815
A transmitter range of 500m is illegal because it would cause interference to many radios. The transmitter is made to transmit audio from your phone in the car to the car radio.
 

Thread Starter

Captain Star

Joined Mar 26, 2023
7
A transmitter range of 500m is illegal because it would cause interference to many radios. The transmitter is made to transmit audio from your phone in the car to the car radio.
I'm living in the French countryside on a farm the size of a small town. The workers here are listening to the same local radio in the workshops and vehicles since there is no mobile network coverage. We communicate through radios and amplifiers like the Baofeng UV-5R. The plan is to have a small FM transmitter to send annoucements over the FM radio.
This would obviously not interfere with radios outside of our working area
 

Audioguru again

Joined Oct 21, 2019
5,815
There was a project in Australia called "The Micromitter" that was an FM stereo transmitter. It had an attenuator on its feed to the antenna to make it legal. Maybe your Chinese transmitter has an attenuator added now that could easily be removed.
 

Thread Starter

Captain Star

Joined Mar 26, 2023
7
There was a project in Australia called "The Micromitter" that was an FM stereo transmitter. It had an attenuator on its feed to the antenna to make it legal. Maybe your Chinese transmitter has an attenuator added now that could easily be removed.
Thank you for your answer.
I will attach a picture of the inside of the transmitter.

Do you maybe know how this kind of antenna protocol is called so that I can do my own research ?
What I can see on the Ebay FM amplifier is an input and a output, but those have three wire/attachments/poles.
Capture.PNG
The HanRongDa HDR-831 only has an antenna with 1 phase/pole, like one single wire antenna.
How can I connect the transmitter to an amplifier if it only has one wire ?

Sorry for the bad terminology.
 

Attachments

Audioguru again

Joined Oct 21, 2019
5,815
Your transmitter has a low output power but the amplifier you found needs a fairly high output power.
The amplifier has a typical gain of 10dB. A gain of 12dB (4 times the power) doubles the distance.
 

Thread Starter

Captain Star

Joined Mar 26, 2023
7
I thank something like this will work put this in ebay 6W FM RF Power Amplifier 88-108MHz or 140-170MHz for VHF Radio AMP w/ Heat Sink and i use rg58 a/u cable and home made ground plane antenna made out of 14awg wire the amp works off voltage at 5v it 2 watts at 7v it 4 watts 8.4v it 6 watts i can run mine at 4.75v and get 1.5 watts
Thank you very much. I will look into that component, it looks fairly better than the one I was planning on purchasing.
I might have to cook up an homemade power supply, maybe also an antenna
 

Thread Starter

Captain Star

Joined Mar 26, 2023
7
Your transmitter has a low output power but the amplifier you found needs a fairly high output power.
The amplifier has a typical gain of 10dB. A gain of 12dB (4 times the power) doubles the distance.
Mmh I see.. So what you are suggesting is that my little FM transmitter might not be powerfull enough to supply the ebay amplifier.
 
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