Sound Card to Microphone

J

jjgonz8band

New member
Hello everyone, I am a "newbie" to recording and broadcasting.

I have a low powered FM Transmitter with a microphone input:

I would like to connect the output of my computer sound card to the input of the FM transmitter. The computer has a generic sound card output, I can connect typical headphones or powered speakers and listen to audio.

When I connect the sound card to the FM transmitter using a male to male 3.5 mm TRS cable I get much distortion, no matter how low I set the volume in the computer. Yet, when I connect the output of my Ipod or another portable Mp3 player to the FM transmitter it almost works, I still get much distortion but, If I set the volume low enough I can hear the Mp3 over the air at a certain FM frequency.

I bought a Line to Mic 35 dB Attenuator:

Sescom LN2MIC-TASDR100 3.5 Line to Mic 35dB Att. 9 Inch DSLR Cable Tascam DR-100

When I connect the output of a portable Mp3 player to the attenuator and then to the FM transmitter the sound quality is good, low distortion. Yet, when I connect the output of my computer sound card to the attenuator and then to the FM transmitter I still get distortion and I can't hear anything, over the radio?

Any recommendations?

Thanks
 
Probably can't help much with the information given and I can't find an instruction manual online for it. The mic input seems specced to be able handle the input you're giving it. Found some Youtube videos sort of demoing it. Try lowering the power output and is the "VOL" setting a volume/gain adjustment for the input?
Did you get a power supply that can supply adequate current at the 12vdc?
A proper 50ohm antenna connected?

A few reviews I saw for this stated it was not working right out of the box (maybe user error?). Perhaps you got a dud?
 
Chili said:
Is that thing legal to operate in the US? it says 10km range.
Click to expand...

I doubt it. I was looking into a FM transmitter that would broadcast 50' to my driveway for client listening in their cars. That kind of thing is illegal now... :(
 
arcaxis said:
Probably can't help much with the information given and I can't find an instruction manual online for it. The mic input seems specced to be able handle the input you're giving it. Found some Youtube videos sort of demoing it. Try lowering the power output and is the "VOL" setting a volume/gain adjustment for the input?
Did you get a power supply that can supply adequate current at the 12vdc?
A proper 50ohm antenna connected?

A few reviews I saw for this stated it was not working right out of the box (maybe user error?). Perhaps you got a dud?
Click to expand...

The Vol setting appears to affect the apparent loudness of the broadcast.

Yes, I was able to construct a power supply with the adequate current. A typical ATX computer power unit can provide enough voltage and current to the FM Transmitter. With a couple of modifications to the power unit I was able to get the transmitter to broadcast effectively.

The antenna is adequate, I can get good FM reception of my station on my car radio when I have the transmitter connected to a portable mp3 player. The problems occur when I connect the FM transmitter to the computer.

Do you think two attenuators connected in series would help?

thanks

john
 
It looks like the LCD can display the SWR which gives an indication of the match of your antenna. What sort of number is it giving?

https://www.hamradiolicenseexam.com/question_pools/technician_2014/T7B-2014.htm

T7B11-2014: What is a symptom of RF feedback in a transmitter or transceiver?
- Reports of garbled, distorted, or unintelligible transmissions
- Excessive SWR at the antenna connection
- The transmitter will not stay on the desired frequency
- Frequent blowing of power supply fuses

Hope you've got a station license for that amount of power. Even down a 1 watt it's iffy if you're legal in the US. :D

I've been toying with getting this one >> Amazon.com: Signstek 7W 7C FM Transmitter Mini Radio Stereo Station PLL LCD with Antenna *Fashion Black*: Electronics which can be set for 1 watt power.
 
Ten k stereo pot in a tin. If you can dabble with DC, i.e. the power supply that should not be beyond you but I can attach a drawing and schematic if required.

As a service tech that saw the Dawn of the Transistor and the difficulty we had keeping RFI out of domestic electronics I am glad you don't live within a click of me!

Dave.
 
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