Introduction: Alternative Hack for FM Transmitter

I also have a FM transmitter that I wanted to hack to improve its range following https://www.instructables.com/id/Hacking-FM-Transmitter/

Another step by step may be not necessary since it's just about soldering 2 wires, so I go with a photo album.

This alternative mainly shows a few differences:
- My transmitter's got hidden screw below black plastic cover. May be this model with 3 buttons always got this hidden screws?
- Instead of removing the capacitor (C2) near the antenna, I preferred to bypass it by soldering a small wire between antenna and closest connection (L1).
- You need to unsolder batteries connectors before being able to access the circuit board, then solder them again (many times for me) to test the new antenna (or maybe you can test with power-in connector?).
- I glued the antenna wire to the board because onboard "antenna" is fragile and a bend is enough to break it.

Some pictures are blurred because I don't have a decent macro camera, I switched to USB microscope but x20 is too detailed in this case.

Hope this helps other hacks! ;)

Comments

author
ClearW (author)2015-06-16

I have got a similar one but frankly, my Raspberry Pi offers better range and fidelity than this one. I get almost 300 ft with my Raspberry Pi.

author
ClearW (author)2015-06-16

I got a similar one from dx and I get a range of around 80 ft out of the box. This was inside the building. I have to check the range out in the open.

author
jimvandamme (author)2015-04-24

I have a car unit that I converted to use on my laptop.Inside it had an antenna terminal with no wire attached. I soldered a quarter wave wire (1 meter) to it and did a relative gain measurement with my spectrum analyzer. The transmitted power went up over 20 dB (that's 100 times). Since it was about the same as other stations in the area but only a few feet away, I figure that I'm safely within FCC limits.

author
alientango (author)2015-04-22

I have the same unit but a different revision. Board is different. Mine actually had no attenna hooked up at all.. Its on the lefthand side. Had 3 L's, headphone cable, the greenish resisitor and one for the attenna (L9). I just soldered a piece of wire to it, and got great results. I played around trying to duplicate by passing like you did, but saw no change.. Oh well, thanks! I wondered where those screws were lol. Now i can actually get 5 feet away from it and still pick it up..

author
raikut (author)2013-04-22

gr8 work buddy, what is the range you are getting now?

author
phmanzano (author)raikut2013-04-22

If you know how to improve range beyond my ears are wide open. And there's no FCC here.

author
phmanzano (author)raikut2013-04-22

Something like 20m inside, it was around 1m originally.
Didn't tested outside yet.
Thanks to you :)

author
Awesome-aniac (author)2013-04-22

You might consider restating the purpose for your hack, even if it is based on another instructable.

author
phmanzano (author)Awesome-aniac2013-04-22

You're right, it seems obvious for anyone with this crappy transmitter in hand: improve range.
Originally it's so low you'd prefer to get a wire.

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