amplifierapplication

amplifierapplication - T&C T&C POWER CONVERSION Power...

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www.tcpowerconversion.com [email protected] Amplifier Application Handbook Power Conversion T&C T&C POWER CONVERSION 110 Halstead Street Rochester, New York 14610 USA Tel: 585.482.5551 Fax: 585.482.8487 www.tcpowerconversion.com [email protected]
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Page 2 of 16 www.tcpowerconversion.com [email protected] Table of Contents Topic P a g e Basic Amplifier Calculations 3 Reflected Power with VSWR 4 Conversion of Voltage and Power Ratios 5 Effect of Attenuating Pads on VSWR 5 Effect of Impedance Mismatch on VSWR and transmitted power loss 5 RF Power Amplifiers: Power Output and Distortion 6-10 N o i s e 1 0 Output Load Impedance and Output Impedance 10 P u l s e O p e r a t i o n 1 1 F a i l s a f e 1 1 Augmented Power Output 11 External Splitters/Combiners 11 Decibels/Volts/Watts Conversion Table 12 Effect of VSWR on Transmitted Power 13 Conversion of Return Loss to equivalent VSWR 14 V S W R C a l c u l a t o r 1 4 AG amplifiers in pulse applications 15 RF Output level recommendations 16
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www.tcpowerconversion.com Page 3 of 16 [email protected] STEP UP TRANSFORMERS The basic relationship is: ( Δ Vrms ( Δ )² load impedance For example, a 100W amplifier into a 50 ohm load produces: Vrms = (100W)(50 ohms) = 70.7 Vrms If customer needs 2 X 70.7 Vrms or 141.4 Vrms, load impedance change becomes: (2)² x 50 ohms = 200 ohms NOTES: 1. If a customer states that he wants higher voltage but the load impedance must remain 50 ohms, the solution is a higher power amplifier, not a transformer. For example, if he needs 141.4 Vrms, P = (Vrms)² P = (141.4)² P = 400 Watts R 5 0 2. If the customer miscalculates the load impedance, he will see the following results from the transformer: a. If load impedance is higher than calculated, higher voltage will be seen, i.e. (Vrms)²=Power x Load R b. If load impedance is lower than calculated, lower voltage will result and the higher current may become an issue. Basic Amplifier Calculations Operation into 50 Ohm Load 50 ohms Load 50 ohms e Vrms 50 ohms R e v i P R For an amplifier, the voltage across a 50 ohms load is given by: Vrms= (P)(50) where P is the rated power In high impedance loads, the output voltage of an amplifier will typically be twice the voltage present on a 50 ohms load. E=2 (P)(50) The power, voltage or current related to a load other than 50 ohms can therefore be easily calculated. i=2 (P)(50) (R+50) P R = (200)(P)(R) (R+50)² V= 2 (P)(50) [R] R+50) Power into a 25 ohm load with a T&C am- plifier rated at 100 Watts into a 50 ohm is therefore: P 25 = (200)(100)(25) =88.88 Watts (75)²
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Page 4 of 16 www.tcpowerconversion.com [email protected] REFLECTED POWER WITH VSWR Reflected power = p ² (Po) where p = reflected coefficient Po = Output power P = V S W R - 1 VSWR+1 VSWR P Reflected Power 1.5 0.20 4% 2 0.33 11% 3 0.50 25% 4 0.60 30% Operation into load other than 50 ohms.
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This note was uploaded on 06/07/2011 for the course EE 11 taught by Professor D during the Spring '11 term at Central Lancashire.

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amplifierapplication - T&C T&C POWER CONVERSION Power...

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