change of vco

by kad on Mon Feb 04, 2013 11:51 am

can i use crystek's 5V vco's instead of mini-circuits since shipping charge in india is as high as 100$???
please reply urgent!!
thank you
kad
 
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Re: change of vco

by lightningserpent on Mon Feb 04, 2013 1:33 pm

Depends on a few things:

1) Are you using RC1a boards or WB2010 boards? RC1a boards use 12v VCOs by default. You can use 5v VCO with slight modification. WB2010 have a 5v VCO jumper (I think, I have only seen the schematic).

2) Are the tuning voltage values within capabilities of the wave bubble? You may need to use a T-Attenuator calculator to determine the correct resistors for the Max Vtune if the values are not the same.

3) Are the pin outs the same with the same footprint? It should be easy enough to check the data sheet of a crystek VCO and compare pin outs and dimension against the mini circuits VCO.

4) Will it cover the desired frequencies? Buying a VCO with a frequency that does not cover the desired range will severely limit applications of a wave bubble.

Really go through the data sheets for both VCOs. Find out what the differences are between the two. Some problems might be easy to overcome (5v VCO on RC1a) where-as others may not (pin out not the same).
lightningserpent
 
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Re: change of vco

by kad on Tue Feb 05, 2013 8:12 am

Thank you for valuable reply on short notice :)
I am using WB2010 boards but Vtune for crystek VCO is limited to 5V max and max operating current is 20mA.
Pin-out is same.
VCO range is 925-970 MHz , but my end application is just gsm jammer, if I jam only the downlink frequency i.e. 935-960 MHz, will it work?
kad
 
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Re: change of vco

by lightningserpent on Tue Feb 05, 2013 11:11 am

The range of the crystek VCO seems extremely limited for a wave bubble. GSM is around 850-900 and 1800-1900 (which is why the wave bubble uses two VCOs). I do not believe you will get the results you want using that VCO.

I built an RC1a and the Vtune boost was 28v. If you want to use a VCO with a tuning voltage of 5v max you will need to adjust several components of the boost section.

My suggestion is to find another VCO.
lightningserpent
 
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Re: change of vco

by kad on Wed Feb 06, 2013 8:34 am

Could you suggest vco's/cross reference of other company.
Today I contacted distributors in india,for mini-circuits VCO, final quotation of them is around 154 $ for 1 piece.
kad
 
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Re: change of vco

by lightningserpent on Thu Feb 07, 2013 10:53 am

Unfortunately since I built my wave bubble with mini-circuits VCOs I do not have any recommendations on alternatives. Auction sites will occasionally have some listed, that how I acquired the GALI-84 pair.
lightningserpent
 
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