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Boost or Amplify IPod FM Transmitter

TheDr

TheDr

Active Member
So I'm not sure if this can be done, and I'm pretty sure it breaks FCC regulations, but I'm searching for a way to boost or amplify the signal from my Griffin ITrip FM Transmitter for my IPod. This is the one that I have and I have done some searching around on the forum but can't seem to find anything about this subject in particular.

I have tried a couple methods of improving the quality (tuning to the 87.7 freq, switching the transmission type to mono) but really notice much improvement. For the most part it works well but sometimes I pick up Howard Stearn from other peoples Sirius transmitters (or other stations from Sirius) or I get static.

I figured if anyone would know it would be you guys!
 
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It sounds more like a selectivity issue with your car stereo then a signal strength problem to me. Just to be sure I'd set it on the hood right next to the antenna and see if that improves it. If so, your car may be shielding the signal from the antenna. Once you know for sure, you should be able to work out a solution.

If your car stereo is hooked to the a Sirius receiver in your car, it may have to be shutdown to receive local FM signals full quieting. It's hard to say without knowing all the particulars.

At least it's a starting point.
 
I used a GPS with FM output and it was touchy. Running the power cable up over the sun visor helped... in your case if there's an audio cable, it may act as an antenna - hang the iPod or the transmitter from the visor.
 
Here's the kicker, my car has some sort of hidden antenna. There's nothing sticking up on the outside anywhere.

As for the Sirius it's other peoples that I pick up, not my own, I don't even have one.

I don't think the cord will reach to my visor. I have a compartment under my radio that I believe is made for holding CD's so I put the IPod in there and also the small box that is used for selecting the frequency it uses to transmit with.
 
I made the antenna longer. it helped a little bit. Not surewhat the best lengt is for 100 mhz.

Learned how to calculate this once, but i forgot. It had to do something with wavelength. so something like frequentie / lightspeed. That would make 100.000.000 / 300.000.000, or more simple 1/3 = 0.33 meters. And depending on your antenna you have to devide that by 2 or 4... again, not sure how it works.

But i hear a lot of these transmission things have decent power, but they have a restrictor.

I would love to give mine a small boost to. When it works mine has a very nice sound quality, but when there is a very weak signal at the same frequentcy things go bad. I have a Venturi Mini, with bleutooth.
 
You take 234 and divide it by the frequency in MHz and you get your length in feet.
For average FM wavelengths it's around 2.4 feet.

You could just get a better FM Part 15 transmitter. Ramsey Electronics sells some good ones and C. Crane has a nice little one also.
Max legal power output of a Part 15 transmitter is somewhere around 25 milliwatts. I think those Ipod transmitters put out a lot less than even that.
 
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There could be a few small issues. To find the best lenght for an antenna, use 1/2 wavelenght lenghts. To find the wavelenght of your certain transmitting station, use the formula 3x10^8 / frquency. Building a signal booster would be difficult without extensive knowledge of high frequency manipulation. You would need to get into impedance matching for proper transmission and a lot of extremly fast components.
 
Maybe this has already occurred to you, but you could also just get a new car deck with an input jack on the front. Even the cheap ones have them now.
 
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