cell jammer wave bubble

[hobiecat]

Ok is anyone working on the wave bubble or at least their version of it? I have been working on my version now for a month or 2 and have some questions maybe others have dealt with. First the basic idea is very straight forward as well there are schematics for different versions of these all over the web. I am using the front end circuit that make use of a quad op amp to integrate a square wave then buffer and mix with a noise signal from the reverse bias zener/386 amp configuration. Although this circuit works it does not work as well as I think it should, mostly in the noise generation portion. For the back end I am using a z-comm VCO and then to a standard rf transistor amp to one really cool smt antenna. When I look at my output on a spectrum analyzer I see a spike at 860 MHz but as far as scanning up from 800 to 890MHz I don’t get a good out. Also I am taking this output directly off the VCO. When I bias my rf transistor as shown in the test configuration by the manufacture the bias resistor gets HOT. But back to the VCO. I thought my front end circuit was less than perfect so I just connected a function generator to the tuning input of the VCO. Again I see a spike at 860MHz but nothing more. any ideas??

I have tried both triangle wave form at 8 V p-p as well as 8V p-p on a 4 volt dc bias as the tuning voltage for my VCO is 1-8 Vdc.

I thought someone here might have already figured out this or had a similar issue.

Thanks HC

[none_such]

you don't seem too concerned with your "cool" antenna - most commercial antennas may be tuned or optimized for 860 mhz thus nulifying any "drift" in signal - try to keep your circuit the same but change your antenna; however, don't operate your rf device without an antenna. Also, try to vary the gain to see if there is any change in the wave scanning (just a suggestion since the bias resistor is quite hot), this would require adjusting the rc aspects of the gain as well as the gain voltage. Hope that helps, let me know how it goes.

[hobiecat]

I the very narrow band I am seeing as a spike is as taken directly from the VCO output via 50 ohm coax to the spectrum analyzer. The spec. sheet for the VCO show a very flat response plus or minus .5dBm from 800MHz to 890MHz. I am seeing nothing of the sort. I as well tried biasing in stable tuning voltages with no luck. I want to get my VCO output looking proper before tuning in the RF amp. Also the SMT antenna was designed for both cell phone frequency spectrums, but until I can get the VCO to operate properly the RF amp and antenna are moot points.
Thanks for the advice though.
Best regards
HC

[none_such]

'I the very narrow band I am seeing as a spike is as taken directly from the VCO output via 50 ohm coax to the spectrum analyzer.'

So the VCO is working out to the analyzer with no impedance mismatch, 50 microstripline and you have a 10dB pad (as per AN-102 app note)

'The spec. sheet for the VCO show a very flat response plus or minus .5dBm from 800MHz to 890MHz. I am seeing nothing of the sort.'

What do you mean? You are taking about power output that the spec'ed VCO (a V580ME03-LF?) states yet you don't say what you are seeing. Does your comparison even matter? In other words, why are you interested in the power curve of this VCO when you are not ampifying and broadcasting the signal? If you see your signal at 860 and you can't see that spike move as you manually vary the voltage (I say 'manually' because the RC jammer circuit you are trying to get working probably is far too tempermental to act at a valid sweep test) there is something wrong with the VCO. Additionally, you need to test and adjust your RC circuit while it is connected to your VCO since without doing so would introduce stray capacidence and throw off any previously tuned state.

'I as well tried biasing in stable tuning voltages with no luck.'

You mean there was no shift in frequency?

'I want to get my VCO output looking proper before tuning in the RF amp.'

Why don't you just use a PLL - that will make the output look perfect and you don't need to futz with it.

'Also the SMT antenna was designed for both cell phone frequency spectrums, but until I can get the VCO to operate properly the RF amp and antenna are moot points.'

I think it is better to test your device with the gain and antenna since the object is to balance the delicate jammer circuit.

[hobiecat]

Ok to help clear things up a bit.
The first link http://www.glowfoto.com/viewimage.php?y ... 6&srv=img4
is to the “generic” schematic I was using except using the Z-com VCO and an out put amp. Other changes I made to the front end circuit was I input the output from the BJT in the noise circuit into pin 2 of the LM386 and tie pin 3 to GND. Also in between the op amp stages I used much lower resistors. The schematic shows 10K and when I used 10K the signal was so small it never made it out. Otherwise the signal I see at the tuning input to the VCO is the same as what the original circuit was.

The following links http://www.zcomm.com/PDFs/datasheets/V580ME03-LF.pdf
http://www.zcomm.com/PDFs/MINIEVAL_Schematic.pdf
are for the Z-comm VCO and a evaluation circuit. My VCC set up is the same as there’s. the V tune is from the circuit I described previous, and my RF out is where I connected the spectrum analyzer.

The last link http://www.wj.com/documents/Datasheets/AG603-89.pdf
is for the output amp. The one I was using is basically same as this one only my range is larger otherwise same part. I again used the component set up and values they used in the evaluation schematic which is shown if you scroll down on the part listing.

OK some answers to your questions. I only see the one spike and when I was saying the spec sheet for the VCO had a very flat response I was indeed saying that they show a very linear tuning curve, where as I only see a single spike. I thought maybe it was my front end circuit so first I took out the noise but this did not help. Then I connected my signal generator to the V tune to ramp the tuning voltage and again only saw the single output spike. Finally I selected individual tuning voltages from a well regulated power supply and again only got the one out put. I connected the RF output from the VCO the input of the output amp and reconnected my spectrum analyzer to the output of the amp. I got nothing and the bias resistor from the application schematic just got HOT. So I shut it down.

Hind site what it is the PLL would have been a better choice however already investing $40.00 in VCO’s I need to make due with what I have. There is a well a chance as you mentioned that the VCO has something wrong with it. I have 2 VCO one is for the 800-890 MHZ the other is the 1930-1990 MHZ. All my work as been done with the 800-890 MHZ and I am a bit reluctant to swap in the other as if my front end circuit is the culprit in burning out the original burning up the other one would seem a waste.

I hope this helps? and again your advice is most welcome.
Best regards
HC

[none_such]

hobiecat,

I am familiar with the schematic you posted, it is originally from GBPPR (Green Bay professional packet radio) web site and it should work with your VCO with no problem. You might want to check out their site for more help (my background is in comp sci not EE) http://www.qsl.net/n9zia/ . If you have trouble accessing any part of the site you can try to view page-crawled archives (ie. google). The one thing I will say again from my first post is not to use your jamming device without allowing your rf signal a proper output: it will destroy the VCO hence my alarm in my previous reply. Another helpful site which you may already know about is http://my.integritynet.com.au/purdic/vo ... lators.htm which has some great tips on rf circuts.
By the way, I never got the schematic you are using for your jammer to work for me - I had already gotten my altered wave-bubble to function before I stumbled on to that jammer diagram- it should work though.

once again,
good luck

[rc:line]

The noise generator isn't really needed.

The LM386/diode idea is a total hack. The LM386 needs good supply decoupling (10 ohm series resistor and large electrolytic capacitor) to avoid oscillating.
It's only meant to drive low impedance (< 32 ohms) loads also.

There are different versions of the LM386, the National Semi "N-1" version seems to work best. The circuit is good for generating a very large noise signal for a broadband jammer though.

Verify your triangle wave generator is working first. It sounds like it isn't. You can also manually vary the voltage tune line on your VCO to determine if the VCO is dead or not. Run the VCO's RF output directly into a frequency counter with like 20 dB of attenuation. As you tune the voltage tune line (like from 1 to 5 volts), the frequency should change.

First thing is to get it sweeping without any RF power amplifiers. Run it into a good 50 ohm load, then move onto the next stages.

If you ran your triangle wave into the VCO without the DC offset, you might have forward biased the VCO's varactor diode, and now it's dead.

Also, run the op-amps from a real +/- power supply. Don't mess with all that 1/2V biasing nonsense.

[stefansandy4u]

i m making gsm jammer but i m not getting maxim vco ic max 2623 and also mar4sm can u tel me alternative for that help me out in this ny ohter way email id is princeover1985@yahoo.co.in

[eren]

hello people, i have a guestion, is it possible to use this jammer for GPS signals either? or it is used just for GSM signals?

i need reply so immediately, if anyone knows please share...thanks a lot...

[none_such]

yes

[loilove]

ok i see, i will try it

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