fm transmitters driving me crazy

[cozzo]

all I wanted was to broadcast my huge library of mp3's from my computer to the various stereos through my house. I bought a cana kit (ck333 mp3 stereo transmitter) and assembled it.the kit was real thorough and easy to assemble for an amatuer like myself I turned it on and wow -it actually worked. here's my problem- tuning this thing sux, and it doesn't like staying in tune either. to tune it you have to adjust a little screw inside an inductor coil, and to make matters worse you can't use a metal screwdriver. now I know I should have bought the kit with the pll tuning, but I'm cheap. so the question is can I use something else to tune with, like one of those little tuner units in a cheap fm radio, or are those little jewels just a fancy trimmer capacitor?
next question, upon all my frustration with this project, a friend of mine who was watching me throw things while trying to get my pirate radio station off the ground, said he had something that might be of interest to me. He works for a fitness company and gave me a fm transmitter that they use in fitness clubs only problem is that it is 900 mhz and has a reciever. I can actually pick up some of the preset frequencies on fm stereo but not well. I opened up the unit and it has an adjustable inductor coil. what are my chances of lowering the freq from 900mhz to standard fm band using this coil or is it not that easy? the unit is a broadcastvision bv900 and it is high dollar ( don't want to screw it up) any help or ideas would be helpful thanx cozzo

 

[cozzo]

I'm waiting......(lol)

ok I see a lot of people looking but no answer, lets pose another question, In the tank circuit of the kit I bought, can't I use a variable capacitor and a fixed inductor coil , or do I need to post the schematics for this kit- thanx again, cozzo

 

[Gene]

I'm afraid I am not familure with the Canna Kit you referenced but, generally speaking, I would not expect a kit to provide a non-drifting signal. It may be possible to limit this with shielding - maybe just putting it in a metal box would help. As to the tuning, small plasstic/nylon screwdrivers are sold at electronic stores for this or you might be able to whittle one from some hard wood.

Dropping 900 MHz to 100 Mhz without a total rebuild would probably not work - the transmitter was designed to operate at 900. This would mean that all of the tuning circuit parts are calculated for 900.

 

[Mosfet]

I have a Ramsey FM10 which sounds very similar.
The little ferrite slug breaks easily and is difficult to tune.
Digital receivers are not kind to wavering signals,
old analog receivers work much better.
Are you using a battery supply?
A fixed regulated supply that is left on 24/7 helped mine.
Perhaps a surplus outfit like Fair Radio would have a heavy duty variable inductor.

 

[cozzo]

hey thanx

thanx for the replies, I will have to take all this into consideration. as for the power supply the kit has one built in to keep it from "hummin". I know everything I've read say's these cheap little boogers will get freq drift with temp and current change,so I guess just leavin it running all the time helps huh?I saw another kit that used a potentiometer that could be used to tune with, that's why I posted the question about the variable cap and a fixed coil for the "tank" part of the circuit.fooling with that inductor sux, I can deal with it but I was hoping for an easier way to adjust it so my wife could use it. again thanx for replies and if anybody out there has any other ideas especially for helping with a different tuner cicuit let me know. Hey maybe I can post the schematics if that would help, or is that copyright infringment[/quote]