Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

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

Status
Not open for further replies.

moindsp

Newbie level 6
Joined
Sep 16, 2009
Messages
14
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Karlskrona
Activity points
1,412
StarTrek Digital LNB

Hello
I am using Ku Band Digital Universal LNB StarTrack ST7000
https://www.worldofsatellite.com

specifications
Input :10.7Ghz to 12.75Ghz
Output:950-2150Mhz
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
 

dorgau

Newbie level 4
Joined
Nov 27, 2008
Messages
5
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,281
Activity points
1,313
Re: StarTrek Digital LNB

Hi,
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

dorgi
 

    moindsp

    Points: 2
    Helpful Answer Positive Rating

biff44

Advanced Member level 5
Joined
Dec 24, 2004
Messages
4,884
Helped
1,359
Reputation
2,714
Reaction score
1,039
Trophy points
1,393
Location
New England, USA
Activity points
36,775
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.
 

    moindsp

    Points: 2
    Helpful Answer Positive Rating

moindsp

Newbie level 6
Joined
Sep 16, 2009
Messages
14
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Karlskrona
Activity points
1,412
Re:StarTrek Digital LNB Proj Deatil

Hi,
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
 

dorgau

Newbie level 4
Joined
Nov 27, 2008
Messages
5
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,281
Activity points
1,313
Re: StarTrek Digital LNB

Right,
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
dorgi
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top