looking for a VCO

[electronics man]

i am looking for a VCO that can output a wide frequance band from a few kHz to as high as i can get, actual freqance doesnt realy matter, I have looked on mouser, digi key, farnell and rs but they all seem to have a pretty narrow frequancy range. what ineed o do is sweep a an Lo frequancy through an RF mixer so i can pick out specific frequancies from the RF. some help would be greatly apreciated.

[Andreas]

Hello,

How about a 74HC(T)4046 or a CD4046 device (not using the PLL phase comparator)
with best regards

Andreas

[Zero999]

You can build your own using comparators: see page 7 of the LM339 data sheet.
http://www2.ensc.sfu.ca/reference/data-sheets/LM339.PDF

[electronics man]

They are a bit low frequancy but I can alwase multiply it with a PLL

[PA0PBZ]

If you need to sweep from very low use 2 oscillators and a mixer. You can buy vco's that can sweep from 2 to 4 GHz, mixing that with 2 GHz will give you 0-2 Ghz after a low pass filter. Is that high enough?

[katzohki]

Minicircuits has some things that might be what you need. They are not listed on Digikey. Some of their stuff can be pricy, but the through hole parts are the cheapest (they call it plug-in). Good luck!

http://www.minicircuits.com/products/Oscillators.shtml

[electronics man]

If you need to sweep from very low use 2 oscillators and a mixer. You can buy vco's that can sweep from 2 to 4 GHz, mixing that with 2 GHz will give you 0-2 Ghz after a low pass filter. Is that high enough?

maybe a bit too high but it would work with lower ones.
so if I use a 200Mhz to 400mhz vco and I put this into a mixer and use a 200Mhz as the lo I can get 0 to 200Mhz after a low pass filter.

[Zero999]

You're being very vague, so now it's near zero to 200MHz, what about jitter and phase noise?

Yes, building a high frequency VCO and a lower frequency oscillator and mixing the two frequencies will give the difference.

You can make your own VCO and the fixed oscillator can double as the mixer.

[electronics man]

well the phase noise and jitter dont realy matter alot but should be as low as i can get and the frequancy should be high but not so high that i cant easily design i circuit so anywhere between 100Mhz and 600Mhz

[electronics man]

are these ok:
http://uk.farnell.com/crystek/cvco55cl-0200-0400/osc-vco-200-400mhz/dp/1582176
this for the fixed oscillator:
http://uk.farnell.com/silicon-laboratories/510aba200m000aag/osc-200mhz-50ppm-3-3v-smd/dp/2393952?in_merch=New%20Products&in_merch=Featured%20New%20Produ
this for the mixer:
http://uk.farnell.com/linear-technology/lt5560edd-pbf/mixer-active-0-01mhz-4ghz-qfn-8/dp/1345583

[Zero999]

The power supply voltage for the oscillator is different to the VCO.

For convenience and to make it easier to interface between components, you should ideally choose devices which can all run off the same voltage.

[electronics man]

 Its  very hard to find a 5v 200Mhz oscillator I could get a lower frequancy one and multiply it up with a PLL 

[Zero999]

Or you could us a harmonic filter - much easier than PLL.