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75 ohm to 50 ohm conveter?

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7rots51

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75 50 ohm transformer vhf

please give a circuit for 75 ohm to 50 ohm conveter?(f=400~500MHZ)

is there any simple and accurate way?
 

Borber

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Circuit depends on allowed attenuation. It can be pure resistive Γ cell or transformer with 1:1.22 ratio .
 

melc

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It could be also a simple layout on PCB and if distance is small it might even don't care at this frequency (assuming the signal source and signal load are not sensitive to impedance variations).
 

7rots51

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please give a circuit with resistor ,LC
 

palesha

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My suggestion is to use transformer type. As ur frequency is just 400~500 Mhz.
If u r ready to waste so much power just to match, then resistive is ok.
All VHF /UHF 300 ohm to 75 ohm convertors r of transformer type.
 

masadi

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Could you give a picture of example 75-50 ohm coverter of transformer type?
if the frequency is higher than VHF/UHF, what kind of 75 to 50 ohm converter will be better to use?

thx
 

7rots51

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if we connect 75 ohm source(or system) to 50 ohm load(or system) what is the loss in dbm in RF power? what is VSWR?
 

BigBoss

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For a single frequency a LC pair will perform this matching but over a wideband, "Wideband Ferrite Core Transformers" must be used to convert 75-50 impedance scaling..
Resistive dividers are very lossy..
 

palesha

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for wideband tranformer matching info refer to

Radio Frequency Transistors
Principles and Practical Applications

Norman Dye
Helge Granberg

Ch. 10 Wideband Impedance Matching

There is a special detailed chapter.
Hope this helps,
 

Borber

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h**p://rapidshare.de/files/21321305/DYE__N.__2000_._Radio_Frequency_Transistors_-_Principles_and_Practical_Applications__2nd_ed._.rar.html
 

Borber

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R1 and R2 are calculated from Eq1 and Eq2. RL and RS are known.
 

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