More FM transmitter mods.

Ok, I changed mp3 players. my daughter started jumping up and down wanting my newer vr3 which left me without an FM transmitter for listening to my podcasts. so I went shopping in a fit of passion of needing a fm transmitter. I looked at the RCA and though "nice price at $14.00 but single frequency? yuck." my only other choices at the megamart I shop were belkin models. so being a cheap bastard I picked the cheaper unit at $19.00 and it had only 4 frequencies to choose from. I picked up the Belkin Tunecast F8V367 and was happy that it sounds better than the vr3 does and has a semi strong transmit but still not enough to overcome a station on the same frequency.

so I fixed it's little red wagon as well. Opening it up I doscovered that it has a BH1417F all in one transmitter IC. this is a cool little IC and with a bit of messing you can even change the frequency range this thing sits on for it's 4 channels. Maybe next time I'm looking for the RF out.... Ahhh pin 11 on this chip is the RF out, it goes through a 1000pf cap and an unknown tiny inductor before it heads off to tie into the shield of the little 3 inch wire that plugs into the mp3 player. So i did my typical trick and soldered a wire that is about 3 feet long on the fourth solder pad (blue wire in my unit) that has a thin circuit trace that heads back along the board. this increased the XMit ability 3 fold. I can once again completely kill the local station transmitting on 88.1.

basically all these hacks can be done easily on almost any FM transmitter . find out what kind of chip is in there, get the specifications and pinout and locate a good place to solder on the antenna that will allow you to use the full RF power of the device.

NOTE: there is a small copper coil on the board near the chip covered in wax. DO NOT mess with this coil or bump it. you will put the unit off frequency and it will no longer work without reforming the coil. this is a problem with open air coils, they are very delicate.

hope you have luck modding your FM transmitter.


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