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Help me identify components of Ku Band Digital Universal LNB StarTrack ST7000

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Newbie level 6
Sep 16, 2009
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StarTrek Digital LNB

I am using Ku Band Digital Universal LNB StarTrack ST7000

Input :10.7Ghz to 12.75Ghz
Local oscillaotr Low Bandwidth: 9.75Ghz
Local oscillator High Bandwidth :10.6Ghz
Noise Figure : 0.3dB
Conversion Gain :55 dB

My semester project is to control change the Local oscillator frequency digitally using msp430 Microcontroller. I am unable to figure out the part numbers , although the inductors and tracks are visible so does the ic numbers but googling the internet i am unable to find the datasheets

Re: StarTrek Digital LNB

don't know what you mean-
but the ic you can see in the atached photo is a 8 bit DACPOT (s9408)
the rest ist just mixer diodes, power regulator and passive stuff,
no magic about it

as for the LOs:
as far as i know, in LNBs they are running free with very high Q based on
those dielectric resonators.
they do not have to be tuned like a synthesizer but you can frequncy modulate them if you varying the dc-power of the oscillating transistor

as you do some math (input -lo frequency)you can see that all of the input band is downconverted to the output - sort of wideband downconversion -
tuning is done in the indoor receiving unit : on the output frequency of your lnb which means output is comparable to a first if in an superhet receiver



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Re: StarTrek Digital LNB

Aye, Short of recalibrating the Di Lithium crystals, there is not much you can do! Those two big ceramic pucks control the frequency, and do not appear to have any voltage controlled tuning mechanism. You can not tune a DRO oscillator very far in frequency, even if they did.

If you really have to do it with that LNB, I would look around for tunable vco's (Zcomm, etc) to replace the two DRO oscillators, and use a micro with two DACs to tune them open loop.


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Re:StarTrek Digital LNB Proj Deatil

My project is to generate frequency of 9.3Ghz, 9.5Ghz and 9.75Ghz with the help of microcontroller using exisiting LNB. I have learned about the working of Ku Band LNB. The SMD DRO as i have learned i cant do much about it , needs to add mass of 1mm or remove 1mm to change 350 to 450Mhz .but its a crude method . I need to as i came across two methods

(1)with microcontroller and DAC pot if i change the voltages at NE622M04 see circuit diagram as well as datasheet, Can i get some harmonic or frequency of 9.3Ghz

(2)Other method is to made three strip line BPF of 9.3Ghz, 9.5Ghz, 9.75Ghz and and after that add UPC3223TB and with microcontroller digitally select the appropriate BPF

Re: StarTrek Digital LNB

first of all, nr 6 seems to be the mixing Diode - most often a pair of two, mixing input and Lo frequency.

to generate these 3 frequencies what comes into my mind is to modify the hole LNB or use it in reverse as an up converter -

generate 450mhz, 250mhz, 850mhz with a pll and vco and feed them into the IF port(output of lnb) or use a vco at 850mhz-1ghz, frequency locked and upc controlled,
generate 850mhz, 450 and 250mhz via diviers and feed them into IF port - watch out for the IF amps nr7/8 - disassemble them
then use LNB mixer to mix these 3 frequencies with 9,75 and 10,6GHz, retune the bandpass and turn around the amps nr 3 - there you get your output frequencies -
try to filter them cause there will always be sum and diffrence frequency in mixing processes

try to find some notes in the internet where amateur radio guys use LNBs to
build 10GHz transmitters maybe they have additional notes

just an idea

hope that helps

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