Belkin Tunecast II FM Transmitter Mod

Step 4 How to boost the FM Transmission power

Well... Not to boost the power, more like removing the attenuation.

This step involves a bit of handy soldering which may be a bit tricky.

Should you dare proceed, the procedure is easy enough, simply bypass the tiny inductor. If you refer to the previous step, you would have notice a blue wire soldered to the PCB via hole, conveniently labeled 'ANT', remove this and stick it directly to where the black wire is on the photo below, the inductor can be left connected to one end, just in case you wish to revert the changes.

An adequate length of this black wire for the antenna can be a quarter of the transmission wavelength, in this case, a minimum of 3e8/108e6 * 4 (c = f * lamda), about 70cm.

Now if you wish to take it further, get a telescopic antenna! I have devised a neat way of attaching the antenna, see second photo.

If you live in the UK, Maplin Electronics (www.maplin.co.uk) has a selection of antenna for CB radio

Comments

[lherrera4]

Alternate Antenna Method: instead of adding a separate wire for the antenna, install the 3.5mm headphone jack and solder one end of a small piece of wire (you can use the blue wire that used to be the antenna) to the inductor bypass point and the other end to the ground on the headphone jack. The ground wire on the line-out cable used to hook up your mp3 player, will now act as an antenna; the longer the cable the better the signal. This works best when the cable is spread out

[michel23]

Just did this mod, on another board.

The first experiment was to extend the antenna. I cut the blue antenna line at 2cm. Soldered a line of 80cm to it. Result: worse than the original tunecast2.

Second experiment: I removed the old antenna (just ripped it off) and soldered a new line to the board on another position, see picture below. Much better result than my first experiment, however, I cannot tell if it's better than the original tunecast2.
Please do not laugh at my soldering technique/result, I'm not very good at this i'm afraid :-)

Third experiment. Note that this step cannot be undone. Using a knife, I cut away that small white thing below my new antenna. It did not seem to make things better or worse. I forgot to make a picture of this, and currently I'm too lazy to reopen the device and take a picture

Tomorrow I'll drive 200+km and will let you know if it made things better or not.

Michel

[michel23]

Result: it seems to make no difference at all, compared to the original tunecast. Still a lot of noise during playback. I cannot recommend this at the moment

[michel23]

Initially, it did not seem to make much difference. However, the following made this work fine:
* I drilled a hole to lead the antenna out of the enclosure directly
* Make sure that the sigaret lighter in your car is tightened securely so it cannot move
* make sure that the antenna cable and the power cable are separated well.

These three all caused interference. Having found this out, it makes the Tunecast useable.

[ferralll]

I did this on my wife's Tunecast, and now it works great. (or atleast part of it) Before, if you were around a city, you would need a lot of luck to find a good station. Now, I can beat out most of the non major (local) stations! Thatsk. What I did (if any one wants to know) I used a good soldering iron, and some VERY thin gold wire (did at work under a microscope) and just made a shunt around the Inductor that you ripped out (ripped up). It works great, and turned it from almost useless, to very effective. I am now trying to do it to my brother in-laws Belkin TuneFM. (this one is much more difficult to open, and the components are much smaller and closer space. If I get the chance, I will post pictures.

[wjie20]

Hi, was wondering if you have succeeded on the TuneFM? Because I'm also trying to mod mine. Would appreciate if you would guide me in to this.

[ferralll]

I have tried to do it with the TuneFM.
But it did not work.

I am going to try again once I get some time. I will post something here if I get it to work.  (there are inductors in different places, so I do not know that I did the right one)

[wjie20]

I see, any luck?

Thanks.

[maizesmagikarp]

Actually, I found that soldering the antenna lead to the grey box-like object directly to the left of the old antenna lead gives better results.

[Lumpy_Carpet]

Sorry if this might be a stupid question, but couldn't one soldier the blue wire to the new connection point and see results?

[scratchr]

yes

[Joby1664]

My Tunecast was different to the one in the example when I opened it. I couldn't find the inductor so I soldered the antenna to one of the legs of the transmitter chip which seemed to be producing the signal. Will this produce the same result or have I made a mistake?

I can't see the equivalent components to bypass the auto shut down either.

[z4c_th3_p4c]

I have the same problem....

[Joby1664]

The tune cast is a piece of junk anyway. I bought this transmitter in the end, http://www.ccrane.com/radios/fm-transmitters/fm-transmitter.aspx. It's outstanding, plus it's incredibly easy to moify, see here:
http://www.xmfan.com/viewtopic.php?t=3257 
They even shipped it to me in the UK with no problems. I would really recommend it 100%.

[lordjohnnym]

mpalins.
the british electronic chain store.
finally someone who mentions stuff you can buy in the UK.
most instructables are american or written for americans.
i bought one of thes transmitters from Tesco, for 7 quid last week, and  it seems that the best quality is at the bottom on the fm band, and the best signal is at the top.
ive been also looking for some way of extending the arial, to give it extra range. i was going to increaser the output wattage, but i remembered that it might blow the diodes.
anyway, what i find funny, how mine is technika, and your is belkin, and they both look near enough the same, and have near enought the same layout.

good instrictable otherwise, keep it up. ;)

[Last_Liberal]

(I apologize for the repeated posts, but I'm not getting any feedback.) I was able to complete the mod and it did dramatically improve the output of my Tunecast (great), but for some reason, I'm only getting the Left channel (no sound from my Right speaker) even thought the "stereo" light is lit on my receiver noting it detects a stereo signal. And yes, the speaker plays fine when switched to regular radio. I'm also getting enough "hiss" to be annoying (no matter what station I choose). Anyone have any ideas?

[Last_Liberal]

I am seriously confused here. You are connecting BOTH the blue antenna wire AND a separate external antenna to the transistor (?) in the middle of the photo (does it matter what end you solder the wire to? Both ends? And how is the inductor "bypassed"? Do you cut one of the leads or run a wire around it? (or both?) Please help.

[Last_Liberal]

Okay, I think I have it now. After blowing up the photos, it appears you soldered a bridge between where the inductor was connected to the left 'L6' contact (the two L6 contacts do not appear to have been bridged), where you also connected the external antenna (the internal antenna does not appear to have been reattached).

If I'm mistaken, someone please let me know. Thx.

[graveyardskank]

really good plans, simple and effective. took me about 10 minutes to do this and the audio quality is perfect over 5 meters, have yet to take the radio further away to asses the range but i am very impressed. transmitter broadcast is strangely directional from the telescopic rod and needs to be angled straight up, gonna be looking for a better shape for omni-directional transmission but its awesome just as you described.

[Last_Liberal]

10 minutes? Yeesh!

I'm having a little difficulty seeing *exactly* where the new antenna wire is being attached or how the inductor was bypassed. Can anyone clarify? Thx.

[emherrma]

Great mod!. I see a 29dB improvement

[thatsmyfox]

I have a diferent version again! The unit really does need this hack though because the range is pants.(UK) Wish I had smaller fingers - I would do this one....

[remork]

Hey, I have the same Belkin as the first commentator on this page (called Lappy). I have included a picture of it. But as my German is superrusty, I don't really understand where to solder the antenna. Is the black element with R18 on it the inductor? On what side of it should I solder de antenna? thanks :-)

[h4d3z]

Having the same problem The board has a R18 thing How do i mod it ??

[jb23rdmc]

Hi what do i do with the blue wire? do i need to connect it any where plz answer my question!@!@!@!@

[Strikah]

My thoughts are that the blue wire is removed and the black wire is now being used as the wire to the antenna. This is just my speculation.

[Strikah]

Sorry for double post, but if you look closely at the inductor and compare it to step 3, it has been taken out on one side

[amzzzziohi]

Soz but I'm still confused. Could you plz explain in a lil more detail what exactly you do with the black and blue wires? Thx I'm trying to figure it out but I'm not sure and I wanna be before I do this.

[Strikah]

It's not like I have done this, but when I look at the pic. The blue wire has been removed and is thus no more used. The black wire, is now connected to an external antenna and is therefore connected back to the FM transmitter. If I look even closer, you see that the Inductor has been removed on one side. On that side you'll have to solder the Antenna. BUT then again, I haven't tested it yet. So if you want to do it, it's at your own risk!

[amzzzziohi]

Ok thank you. I started to study all the pics closely and I came to that conclusion. I hope urs works lol if you did it. I'm gunna try it on my Belkin Tunebase (the one that plugs into the base instead of the earphone jack). I have a basic understanding of circuits, I made a circuit for a flashing LED for a school project lol. I'll get some help from the 'techno' guy at school. He once made these awesome speakers and bought 'em to a carnival.

[shaunp]

Cheers Buddy, OK well I bought two of the Belkin Tuncast II, and performed the Above on one of them. Now What I found is that on mine above the inductor (which is black and more cube shaped) is a small resistor were the black antenna is soldered in the above pic. So for testing i just used a small 10cm piece of braided wire and by hand put it on the (LCD Bottom Down Side) leg...and it improved the signal to quite a bit. Now After trying this is decided to get the solder iron out and after try to attach the new Ant to the spot basically the same as above but on the left leg of the resistor. In the end i basic shorted the resistor. So imagine the above picture were the new (black) ANT goes is actual covering up the Resistor...Now the Inductor is still in the same place and has not be moved at all and the main (blue ant) is still intact and attached. Now this works better than the other unit.(Non Mode) But still can't get than 3 meters away without signal Degradation. Should I remove the old ANT? (Was going to anyway). when you say remove the inductor do you mean just lift one leg off the board a slight. And in your above picture did you have a small Resistor under the Solder of the Black Wire(ANT)? If not what exactly are you soldering on two is there a Silk on the board at all list say R16??. the above steps that i took seem to work to my Satisfaction as i just wanted it to be in the backseat of the car or Glovebox...But on the other belkin that i have not even opened yet. I wish to perform the same mod but hopefully would be better Transmitting Distance...hence this time i will run the wire out of the device to see how much improvement it will make...Any help would be great....Basically just need to know whether i was suppose to solder the new ANT over the resistor above the inductor(Can't bee seen well enough in PIC above...but were the Black wire is attached I have a small resistor(I think it's a resistor)..Will take Pic's when have CAM Handy...

[kanamin]

I have the original tunecast (four stations, no LCD), and I was going to ask where do I solder the new antenna for the old one, but I followed the tracer from the existing antenna and it leads directly to an inductor :D the inductor on the old one and the new one are both labeled L3 by the way

[4n8only]

Thxs for posting this but what do you mean "black wire", i am new to this. Is there a specific wire or will any do? i'm assuming u mean electrical wire?

[Corrugator Supercilii]

It is the specific wire as identified with the colour black

[cereal1]

Okay, I just went ahead and did this mod, but took the antenna wire and wrapped it up between the circuit board and the battery holder. I can hear the transmission at the other side of the house, but it's always full of static wether the Belkin is right next to the radio or across the room.

[berky93]

maybe interference caused by the electronics in the device?

[cereal1]

So do I really need 27 inches of wire dangling from this for it to work? Or can it be wrapped up? I always use it plugged into the Car Adapter, so if I could just wrap up the wire I'll put it where the batteries usually go.

[Cascadia]

Having a rather clunky soldering iron, I was not able to remove either end of the inductor (labeled L5 on my PCB). However, I was able to simply solder a new antenna wire to the inner side of the inductor, and after snipping the blue wire off, the thing works great.

[Lappy]

German:Hi leute,befinden sich deutsche user hier im block?Irgendwie ist meine platine anders aufgebaut als die hier vorgestellte. English:Hi guys,sorry for my english. My tunecast panel is a different than your panel. Can you give me record where the new antenna soldered?

[tantales]

German: Trenne das braune Antennenkabel von der Platine und löte die neue Antenne (das 70cm Kabel) an das Ende des als Inductor bezeichneten Bauteils, welches vom alten Anschluss wegzeigt. Bei dir wäre das am kleinen schwarzen Kasten das "untere" Ende. Find the connection to inductor that is not connected to the old antenna and attach the new wire over there. Don't forget to disconnect the old antenna! Should work for any similar design.