Microwave Forum

viki · Guest

in your test circiut parts that atteched before VCO are eoungh of make test cricuit?

kleiner-onkel · Administrator Messages: 412 Location: South-West-G

***** what does VCO mean ???? *****

... maybe Voltage Controlled Oscillator ...

!!!! so it's even not possible to jamm without a RF oscillator !!!!

1st. Build noise circuit .... look out for LF waveform on a oscilloscope.
(if you don't able to do this ... forget it!! & don't read more!!)

if it shows the right waveform ....

(waveform is not critical for only a few meters coverage and testing)

2nd. Connect the VCO & took a 900Mhz scanner or sat receiver (or even cell phone)

if the noise is clearly on our receiver and depending on LF frequency ... connect the hybrid power amplifier ....
(if you don't able to measure RF power .... forget this option!!!)

How about our identities ???

aethr · Guest

weird, I have a MAX2623 wired up according to the spec sheet. The oscillator works as I can tune in to a TV tuner turning the screen black.
Through a small piece of teflon coax I connected up a MMIC, the ERA-3SM, much like in kleiner-onkel's jammerII. I biased the collector current to the spec; 35 mA.

BUT, the amp is not amplifying at all.. as the output from the MAX is about -3 dbm (0.5 mW) and the ERA has a gain of about 20 dB, I would have expected some good mW (spec. o/p = 11 dbm).

I double checked everything and even swapped the ERA for a new one, but can't find what's going on.

Any one has any ideas?

Thanks a bunch.

aethr

BTW I also ordered a POS1060 to see if it's output can directly drive a PF08109B. Any experiences to share?

æthr · Guest

another question, when using a POS1060 to sweep the GSM band, what tuning voltages are people using? Or what to set the tuning voltage to for the middle of the band and what noise amplitude do you use?

Thanks

æthr

richy_64 · Administrator Messages: 198

Hello,
can you make a picture of your current circuit? Or a wiring diagram?
Normally your circuit will work, maybe there is little fault in the circuit yet.

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A POS1060 an a PF08109B will definitvely work together.
Even MAX2622 and PF08109B.

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Tuning voltage for POS1060: Look at Kleiner Onkel´s Jammer I on his homepage. :-)

Generally....
To find the correct tuning voltage there are different ways, first:
Look in the datasheet of your vco to get the suitable voltage for ~940 MHz.
Or use a frequency counter

Or (i prefer this):
Build a vco circuit with a adjustable resistor to tune the vco. Connect a sweep or noise generator to modulate the vco, too.
Put a mobile in the near of the circuit a call someone (or a free service number). While the calling, turn the adjustable resistor. You will see that there is a small range where the mobile is jammed. Tune to the middle of this range... ready.

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Noise amplitude: Your have to estimate this (but it´s not so critical). First, use the datasheet of the vco and find out what voltage difference causes a frequency difference of, let me say, 50MHz.
Then modulate the tuning voltage of the vco with a noise or sweep signal with a value to reach +-50MHz.

Richard

kleiner-onkel · Administrator Messages: 412 Location: South-West-G

Hy…

… noise voltage of the pos1060 is around 17 to 23 V ... but there are
harmonics too ,,, so try looking after the strongest signal, and this is the main carrier.

You don’t need to adj. to the centre frequency on my circuit if our offset is from ~ 17 to 23 V.

Watch after the pos1060 datasheet for more information.

Chris

aethr · Guest

ok, thanks for the info. At the moment I don't have the time to draw up a schematic, so what's wrong with my 2623 and ERA remains to be seen.

I now have a POS1060 and have it rigged up. So far I see a really strong signal on my TV set, so that's good. I biased the tune input to around 8 V and imposed a triangle with some noise. My Motorola phone looses it's network, but I need to keep the antenna really close to the 1/4 wave wire antenna hooked up to the POS.

When I look at the datasheet, I see a voltage of around 10 V to tune it to ~ 920 MHz.

So the question is, why does Chris use ~ 17-22V as a tuning voltage? The sheet says it corresponds to ~ 1070 MHz..

Ok, just bought a MB506 to prescale my counter and see who's right

æ

æthr · registered user Messages: 3

ok, had to swap my zener diode to another one; having a good steady 6V noise now. (How can one develop anything electronic without an oscilloscoop I wonder.

)

This improved the spectrum damage, hence my phone drops of the network more easily. Now rig up that PF08109B to get some more reach. How do people here keep that ceramic piece of tech from overheating? Now it lays flat on some double sided PCB with the connections cut out of the copper. Should I mount some lumb of aluminium to the bottom?

æ

don't send private messages, I don't read them

viki · Guest

say u said that noise generator Power supply: 9-12V should be fine
is it fine for MAx2623 bcoz its just working on 5v

æthr · registered user Messages: 3

say u said that noise generator Power supply: 9-12V should be fine
is it fine for MAx2623 bcoz its just working on 5v

yes, but take care that you feed the noise through a capacitor, so you block the dc component and just let through the ac noise. You could use a cap of say 100nF. The tune input on the MAX can be biased (set to an offset voltage) by means of a regular R/R voltage divider or a potentiometer.

Look at the schematics and you see what is meant by this.

æ

ps: is it possible to draw fixed width ascii art in this forum?


o---\/\/\-----+-----\/\/\---o
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 +---||----o test

nope

plz don't send private messages, I won't read them

richy_64 · Administrator Messages: 198

Getting 5V for the MAX2622 is the smallest problem, isn´t it?
7805, 78L05