SSTRAN AMT3000 Transmitter
Modulation and Frequency Response Waveform Displays
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Test Setup |
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Transmitter Frequency: Transmitter RF Tuning: Antenna: Audio Source: Oscilloscope: Top Trace: Bottom Trace: Scope Vertical Volts/Div: |
1610 kHz Peak resonance at operating frequency Supplied 3 meter wire Waveform generator software running on PC Tektronics Model 475, dual trace, 200MHz
bandwidth. 10x Tektronics probes Audio in at "Audio In 1" RCA jack Antenna RF coupled by clipping scope probe
to insulated antenna wire. Set to give good viewable waveforms. Once
set, kept constant for all pictures |
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Waveforms Showing
Results of Various Modulation Levels Audio input level held constant. COMPRESSION control: fully counterclockwise to disable
compression MODULATION control: fully clockwise to disable limiting GAIN control: varied to achieve 50%, 100%, and 115% modulation
levels |
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Audio Frequency: 1000 Hz Horizontal Time/Div: 500 us Modulation Depth: ~50% (under-modulation) |
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Audio Frequency: 1,000 Hz Horizontal Time/Div: 500 us Modulation Depth: 100% |
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Audio Frequency: 1000 Hz Horizontal Time/Div: 500 us Modulation Depth: ~115% (over-modulation) |
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Waveforms Showing RF
Amplitude at Selected Audio Frequencies In Range 20 Hz to
20,0000 Hz Audio Input Level and scope vertical Volts/Div kept constant for
all pictures. COMPRESSION control: fully counterclockwise to disable
compression MODULATION control: fully clockwise to disable limiting GAIN control: set to 100% modulation level GAIN, MODULATION and COMPRESSION control settings kept constant
for all pictures. Scope horizontal Time/Div varied as required to show good sine
wave visual resolution. Amplitude of the RF waveform is the same at all frequencies demonstrating flat 20Hz - 20,000Hz frequency response. |
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Audio Frequency: 20 Hz Horizontal Time/Div: 10 ms Modulation Depth: 100% |
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Audio Frequency: 500 Hz Horizontal Time/Div: 500 us Modulation Depth: 100% |
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Audio Frequency: 1,000 Hz Horizontal Time/Div: 500 us Modulation Depth: 100% |
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Audio Frequency: 2,500 Hz Horizontal Time/Div: 200 us Modulation Depth: 100% |
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Audio Frequency: 5,000 Hz Horizontal Time/Div: 200 us Modulation Depth: 100% |
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Audio Frequency: 7,500 Hz Horizontal Time/Div: 200 us Modulation Depth: 100% |
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Audio Frequency: 10,000 Hz Horizontal Time/Div: 50 us Modulation Depth: 100% |
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Audio Frequency: 12,500 Hz Horizontal Time/Div: 50 us Modulation Depth: 100% |
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Audio Frequency: 15,000 Hz Horizontal Time/Div: 50 us Modulation Depth: 100% |
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Audio Frequency: 17,500 Hz Horizontal Time/Div: 50 us Modulation Depth: 100% |
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Audio Frequency: 20,000 Hz Horizontal Time/Div: 50 us Modulation Depth: 100% |
