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FM Transmitter not broadcasting


KeysNole

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I purchased the popular CZE-7C and cannot pick up any signal in our vehicle parked 50 feet away. We have adjusted the gain on the transmitter, volume on the computer, antenna length/direction, placed the transmitter inside/outside, tried a different computer, and tried different radio stations. Transmitter seems to be functioning properly.

After reading through anything I can find on here, it seems like a rubber ducky antenna might be the solution, but it seems as though I should be getting SOME action out of the transmitter.

Any thoughts?

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Keys

 

You didn't say, but it does have some kind of antenna installed correct? That would be an absolute first, then of course proper hooking up and wiring, after that if still no transmit it may be defective. I use the CZH-05 so i can't give much more advice on the 7, some more help should be along shortly.

 

Keith

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The first thing is to determine if this is a RF issue or a modulation issue.  Disconnect the audio cables from the transmitter, and turn down the level control as far down as it will go.  This should result in a transmitted signal with no audio on it (what we call un-modulated or a dead carrier).  Now go to your car and tune to the station.  Do you hear a rushing static noise (like you get when you are on an unused frequency, or is it very quiet?  If it's quiet, drive around a bit and when you get far enough away, you should start hearing the static rushing noise.  When you get closer, it should get very quiet again.  If this works, the radio transmission part is working fine.  Now it's just a modulation issue.

To work on the audio, if you have an audio cable that will go from some convenient audio source (laptop, walkman, mp3 player, etc) to the transmitter, plug that in.  While monitoring your own transmitter (on a portable radio, or your vehicle radio), start with the audio from the source turned all the way down and the audio level on the transmitter tuned all the way down.  Then start turning up the audio level from the source a little bit at a time.  Alternate that with turning up the audio level of the transmitter a little bit at a time.  At some point, you should start hearing the audio over whatever you are monitoring with (your portable radio or vehicle radio).  Once you can hear the signal, you can fairly quickly adjust some combination of the source audio and the transmitter level control until it's a reasonable level.  A reasonable level is about the volume as a local FM commercial station (or a little lower), AND no distortion of the signal.  If that works, you know that the transmitter is working properly.  The biggest issue most people have is trying to send massively too much audio to the transmitter.  That's why I tell people to start with all the audio levels turned all the way down and bring up the volumes just a little at a time so you don't end up WAY too high.

And as was mentioned, DO NOT EVER turn on that transmitter without an antenna - even for a fraction of a second.  You can damage the transmitter faster than you could turn the power back off..

 

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Nothing but static tonight.

I should say that in the 20-30 times I have tried to troubleshoot this, a very very faint signal full of static has come in twice.

I might think it is some of the electronics in the room, but we have put it outside, and only 50 feet away from our vehicle.

 

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Keysnole

Have you found the problem yet? I just had a thought, have you checked the audio volume out of the PC, i was thinking with the 3.5 mm plugged in you wouldn't  realize if it was muted or turned way down thus not giving the CZ the right input.

Keith

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On 12/14/2016 at 7:19 PM, KeysNole said:

Nothing but static tonight.

Make sure you're on the right frequency.  Note that if you go into setup on the transmitter to change frequency or power level, you must make sure you get out of that mode or wont actually be transmitting.  That got me once when I was doing some testing.  If you really are on the frequency and you followed my steps above, you have a broken transmitter.

On 12/14/2016 at 7:19 PM, KeysNole said:

I might think it is some of the electronics in the room, but we have put it outside, and only 50 feet away from our vehicle.

Very unlikely.

 

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23 hours ago, k6ccc said:

Make sure you're on the right frequency.  Note that if you go into setup on the transmitter to change frequency or power level, you must make sure you get out of that mode or wont actually be transmitting.  That got me once when I was doing some testing.  If you really are on the frequency and you followed my steps above, you have a broken transmitter.

I actually took the plunge and purchased a CZE-05B. The good news is that your recommendation for going to the channel in our vehicle and transmitter/unplugging the audio cable did give us the silence you were asking about. Then when we inched up the volume as recommended all we received was static. No music whatsoever. Laptop appears to be working (same laptop and outlet work fine with hardwired speakers).

My display screen says "ST" on it (stereo?). If when I change the transmitter setting from high to low, I get the speaker with an x over it on the display. No music. If I hold the off button the x over the speaker disappears. Still no music in the car.

I have also noticed that at times both of the transmitters will have a limited range of frequency choices.

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that transmitter mutes in set-up mode.  You should see a speaker symbol with an x through it when in set up.  You have to exit that set-up and then it should be transmitting again.  The X over the speaker will disappear so you know you are transmitting.  If you've done that and still nothing than I suspect you have a defective unit (as others above have stated).

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keynole -

I know the music plays through your computer speakers but does it play when you attach head phones in to the 3.5 Jack? 

 

edit ; what I mean is does it play through your head phones when you hook up the head phones.

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