Modifying a Cheap Portable Cellphone Jammer

Step 3 Adjusting the caps

In this step you just want to adjust each set of caps until you locate the correct band to block out whatever carrier or network you want to block.

in order to adjust the caps its best to use a small screwdriver, either a phillips head or a regular will do, you don't want to use allot of force here as the capacitors are very sensitive to force and could break.

If you have a frequency counter this step will be very easy as you can precisely tune your jammer, without a counter im afraid its pretty much guess and check. The easiest way I have found to do it is to call a number that continuously generates tones or some kind of audio
and then sit about 15 feet away and slowly turn the knobs until you hear the phone drop out

Here are some useful reference frequencies for tuning.

Cingular 1.850-1.865 Ghz 1.930-1.945 Ghz 1.730-1.735 Ghz 2.130-2.135 Ghz

Sprint 1.865-1.870 Ghz 1.945-1.950 Ghz 1.885-1.890 Ghz 1.965-1.970 Ghz

Tmobile 1.895-1.910 Ghz 1.975-1.990Ghz 1.710-1.720 Ghz 2.110-2.120 Ghz 1.740-1.745 Ghz 2.140-2.145 Ghz

Comments

[Qsam]

I tried to remake mine to disturb out my mobile but it took out my wifi :D

[nayrjm6]

I just got mine from lightinthebox.com, havent really tested it yet but it takes out verizon to about 10-15 feet without any modifications

[BOFH_2]

 You work in my office don't you... :)

[Redgerr]

lol, taken down

[REA]

anyone know the settings for Alltel?

[eMikey]

I wonder what way NAK turned the pots.. clockwise, or counterclockwise. Anyone?

[jakobgrau]

Hi everyone! I recently bought an inexpensive frequency counter and came to discover that "clock positions" have very little to do with the actual frequency when tuning the pots. Actually, although some of them require only very fine adjustments, others need to be turned several times before the desired frequency is actually reached. I have also noticed that the 3G pots on my jammer won't tune all the way up to the 2110 and higher range. It just stops moving up just before reaching 2100 :(

[jasontimmer]

I'm a little confused- so 6 caps means 6 different frequencies that can be jammed? Am I totally wrong?

[balthaz]

hello everybody i have a problem to configure my jammer I'm in france and te frequency is: GSM900: 925 - 960 MHz GSM1800: 1805 - 1880 MHz 3G: 2110 - 2170 MHz Also i have a frequency counter, but i don't know the exactly frequence to my country: ex: GSM900: 925 - 960 MHz --> i can't put the two frequency... an other probleme, for the 3G my jammer can up to 2070 Mhz, is it normal thanks in advance balthaz

[sunrey]

...just got mine out the box, I've already got a smile I wont hear screaming in back of my head in Mid Town MaNHATTAN. Shuts down Sprint very easily, and verizon a little slower? Im concerned about the battery exploding when charging, any suggestions?

[bobalouie]

I agree with WildWeasel below; mine has a built in charging circuit protector and the led light goes off when fully charged. It works great. I tuned it using the diagrams available on this site.Range, depending on brand of phone has been, been 2ft. to 20ft.

[WildWeasel]

No problem with the battery on my mine - I have left it on the charger overnight and it appears that it has a protective circuit. The charging light (on the base of the unit) goes out when it's charged and no damage gets done. Range and jamming time depend on the relative strength of the signal you are jamming, which is a function of the distance to the base antenna. Where I live the signal strength on my Verizon phone is usually 1 to 2 bars and the jammer can knock it out at up to 60 feet. Much less than that when I'm getting 4 bars.

[somniloquist]

Any Canadians out there with tips on how to tune the pots on this device? I read the settings below, but I'm not sure on how to orient the pots to match the clock settings. A photo would be really helpful and I would be very grateful. Thanks!

[ericmann]

I just set it to work for northern Idaho cingular/att. let me know if anyone has working settings for verizon in USA, pots 3 and 4. I will share settings if anyone needs.

[ericmann]

Yes, I tuned mine last night so now it works amazingly well with att and verizon. The looking at the device (antennas up) starting from the top left (4 pots in a row). The first two are cingular/att second two are verizon, and the vertical two are for sprint/nextel. Let me know if you have anymore questions! HOped that helped.

[mike13]

Is there a reason Verizon has two pots? Shouldn't each carrier use one pot? I have mine adjusted to the diagram but it won't take out Sprint or T-Mobile. Haven't had a chance to try Nextel.

[dougharr]

Ericmann, I have on one these and the only thing it jams is Verizon. do you have any idea which pots control what???? how are the pots numbered clockwise or counterclockwise??

[JackSnap]

Im only getting about a 30cm range, battery seems fully charged?

not tried soldering the contacts yet, (dont have the equipment)
anyone tried a device to compliment it like this?
http://www.alternativewireless.com/cellular-antennas/wilson-antennas/wilson_cellular_amplifiers/wilson-signalboost-universal-amplifier-dual-band.html

[Jay$]

screw that, for that price just get one of these.
http://www.dealextreme.com/details.dx/sku.7708

I don't think it'll work with the device that you suggested anyways. (correct me if i'm wrong)

[maximillion]

This one seems decent http://www.dealextreme.com/details.dx/sku.7709

I also broke my power button. I took it apart the first time fine, I made a couple tweeks and messed up my range. I didn't realize until I put it back together so I took it apart and this time forgot to pull out the power button. Well I got so mad I chucked it against a wall and broke the rest. lol. I think I'll be trying this puppy.

http://www.dealextreme.com/details.dx/sku.7709

[Jay$]

If you do get it, let me know how it works. I'm debating on whether to get that one or the higher power one.

[maximillion]

How long do you guys charge the battery?

[ELECTRA]

Charge until the light goes out. Takes about 4-5 hours for a fully drained unit.

[maximillion]

Thanks. SO I tested out the distance and I can get about 8-10 feet away. I will take this apart and solder the posts to see if they help. Do you believe that this helps?

[thebigdr]

It won't hurt, but it will only help shore up the mounting to the board. The antenna posts are soldered to ground on the opposite side of the board and each side's grounds are connected to each other. 8-10 feet is pretty good for a 'personal' jammer. Also, if you get a good jam at 10 feet, it will wreak havoc beyond that a little if you just let it run for a minute. I notice that it takes 10 secs. before it will knock out my service (Verizon).

[maximillion]

So boom! out the box, verizon stops working. I did the attena switch and no problem. I need to find someone with a solder iron to get the posts in. I haven't messed with distance yet but will do. At my work the signal is bad enough, most people are lucky to get one bar. This will shut it fast. lol

[maximillion]

Electra, Can you please explain how you switched the attenas? Which ones you moved to where? Thanks

[ELECTRA]

Maximillion, I have switched the GSM and the DCS antennas as per the accidental discovery of "jimmynonomous". He removed his posts (I believe) I don't know why. Does this improve anything? I think so! The greatest steps forward for me was the antenna switch AND the soldering of the rectangular antenna pins as per "Blocker". Still my range seems to be about 5 to 8 feet....if I exagerate I can say 10 feet. For the first time I had a sucessful kill on the bus. 3 people where on the phone, one real close (4 ft), one at about 8ft and one at 10 ft. I turned the unit on and disabled the one at 8 ft. They where disconnected and where unable to reconnect despite numerous attempts. THe other 2 people where unaffected. I believe the one I disabled was a GSM 800. The others must have been on 1900 (Canada). I have tried other switches with the antennas but the above-mentioned gives me the best results. Keep in mind there are 2 versions of this unit (as per the instruction manual) so tweaks may vary. Using the clock to indicate pot positions (starting from the top left,I have 4:30, 4:30, 2:30, 4:00,5:00 and 1:00 (with the soldering and the antennas switched. Post your results.(that goes to everyone). Looking forward to your reply.

[esunday-deleted]

(removed by author or community request)

[ELECTRA]

Excellent. Can you describe your test? Distance? indoors? outdoors? Also where did you get the settings, 8,6,10,7,4,10?? I do not recall seeing them here.

[webejammin]

electra: your clock pot positions worked *great* for me. I switched the GSM and DCS/PHS antennas too, but did not do any soldering (yet). with those pot settings, I've been killing Blackberries no problem. the lack of battery power safety in this unit is very, very alarming. over/under charging will lead to explosions? yikes. any more advice on how to safely handle this small time bomb would be appreciated.

[ELECTRA]

webejammin:
Congrats on your success. What range are you getting? Which providers are they? We have to keep track of the Frequencies that are knocked out by certain modifications.
Battery: Again there are 2 different units. One has the battery simply hooked up by wires soldered to the contacts, the other has the battery hooked up like a cell phone where it is "snapped" in place to make contact. I have the soldered wires. Just to be safe I think we should not run our units too long. Once you feel it is hot to the touch, shut it off. Another thing would be to replace the battery with one that has a built in safe guard. Perhaps some one can do some research and find one on dealextreme that would serve as an ideal battery. Keep us updated with your discoveries!!

[187inc]

if your using the DX model cut out the back of the metal casing and epoxy in a 3.5v solar panel. solder the wires directly to the battery. improved battery life and runs cooler.  no other inner mods yet.  works great, best 25 buck ever spent. 

[o0JohnnyReb0o]

Yes, PSP batteries , there are some 2200MaH and 3.6V and a protection circuit is integrated

[webejammin]

I don't know what network it was on. I sat on a park bench, and no one with their blackberry could get a signal. but hey, I'm in the financial district of manhattan. for those of us in big cities you'd need a pretty big jammer to knock out people outside a very small radius. there are just too many cell repeaters in NY.

[ELECTRA]

Good news! You need to keep testing it is differing scenarios and be certain of the knock out. I find that in my tests it is hard to tell if the person just hung up etc. Find out what networks are in your area. Surely it must be advertized everywhere "Verizon" etc. That way you (we) can know if you are knocking out GSM 800s CDMA 1900s etc. Keep trying, let us know.

[3ricj]

You can't see the pot labels in the above photo; for those of you wanting to tune your device, here's the info: v3 - 900mhz High trim v4 - 900mhz low trim v5 - 1800mhz high trim v8 - 1800mhz low trim v7 - 2100mhz high trim v6 - 2100mhz low trim AFAIK, you can't trim the 1800 above about 1906mhz, which sucks for blocking GSM1900, as you need to block 1930-1990mhz. I've been able to trim the 900mhz to about 869 to 960mhz, which is what you want to block GSM850. The highpot trims have a very steep falloff (32db/mhz or so), but the lowpot trims are more like 4db/mhz falloff. My spectrum analyzer only goes up to 2.1ghz so I was unable to calibrate the 2100 freq. There is likely a method for extending the range on this device; I'm just not sure what it is. FYI, these are 5k pots, not variable caps. You do not need to have a ceramic screwdriver if you are careful not to touch the PCB and you keep your hand 4-5" away from the board/antennas.

[ELECTRA]

Thanks! Could you post a photo of your tuned pots? It may not be the setting I need for Canada but at least it gives me a place to start as I do not have a spectrum analyzer. Thanks and keep posting.

[blocker]

Photo is attached. Note the rectangular pins on the lower left connector. They are not soldered to the pc foil. Only the center pin is soldered. By soldering the two pins, the signal output increased on the receiver. As far as the antenna, I used 1/2 wavelegth. For 1900 MHz is is 8 cm, which is long. First I tried a straight #18 wire and the signal was good at 1900 MHZ +/- just for experimenting. Following that, I made the wire into a spiral of approximately 1/8" diameter with straight portions of 1/2" and total length approximately 1.5" and the signal was still strong. I am able to tune from roughly 1850 to slightly over 2000 MHz. Still working on it.

[ELECTRA]

blocker, Thanks for the reply and keep us updated! Here is what I have been able to find.
Hold the unit so the antenna faces the up. The Left antenna labeled GSM/CDMA is controlled by pots 1+2, the middle (labeled 3G) controlled by pots 5+6, the third (labeled DCS/PHS), is controlled by pots 3+4. I would like to know how to get the GSM and DCS (pots 1+2 & 3+4)to the exact middle frequency of the downlink Canadian 850 and 1900 band range (880 and 1960 MHZ).
Have you noticed also that many of our units are slightly different? I cannot see on your picture the area below the pots (nor your pot settings could you post a larger pic perhaps on flickr?) but some of us have caps? at "c22" and "c13" on the board while others do not. This must increase or decrease the frequency range and explain why some people are able to "knock out" all phones at good distances. Thanks. Looking forward to your next post!