Difference between revisions of "RF-Amp"
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== LT Spice Simulation == | == LT Spice Simulation == | ||
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=== Transformer 35 uH === | === Transformer 35 uH === | ||
Revision as of 09:46, 6 November 2021
Contents
RF Amplifier Features
- From Charlie Morris' (ZL2CTM) Go QRP Portable SSB Rig
- Solid State Design for the Radio Amateur?
- +22 dB gain
- Input connectors: SMA or BNC
- 49x49mm card
- 4x 4-40 mounting holes
RF Amplifier Design
Schematic
DC Operating Point
- Ice = 10 mA
- Ve = 0.1 * Vcc = 1.2V
Input/Output Transformer
FT37-43 Toroid
- FT37-43
- Wideband Transformers 5 - 400 MHz
- Power Transformers 0.5 - 30 MHz
- 10 turns = 35uH
Tracks
Input Transformer
- Input Transformer (T1 on Charlie's - T2 on this board)
- 50:75.8 Ohms = 1 : 1.23 turns ratio
- 9 turns primary, 11 turns on secondary
- 50:75.8 Ohms = 1 : 1.23 turns ratio
- Input Transformer (T1 on Charlie's - T2 on this board)
Output Transformer
- Output transformer (T2 on Charlie's - T1 on this board)
- 200:50 Ohms = 2:1 turns ratio
- 10 turns primary (on transistor collector), 5 turns secondary (towards output)
- Output transformer (T2 on Charlie's - T1 on this board)
LT Spice Simulation
Transformer 35 uH
Charlie Morris Schematics
IF AMP
- From Charlie's notes
- DC Operating Point = 10 mA
- V(emitter resistor) = 1/10 Vcc = 1.2V
- R(emitter resistor) = 1.2V/0.01A = 120 ohms
- Beta DC = geometric mean min/max beta at operating current
- = sqrt(100*300) = 173
- Beta AC = gain bandwidth product divided by operating frequency
- Assume operating frequency of 10 MHz (my IF is actually at 9 MHz)
- = 300/10 = 30
- VCE = 0.7V
- V(emitter) = 1.2V
- V(base) = V(emitter) + VCE = 1.9V
- Assume current in biasing resistors = 10x current needed by DC beta
- 10 mA in C-E, beta DC less = 10 mA/173 \
0
Video
