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7L13: Difference between revisions
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{{Spec|Input frequency | 100 kHz – 1.8 GHz}} | {{Spec|Input frequency | 100 kHz – 1.8 GHz}} | ||
{{Spec|Span | 200 Hz/Div – 100 MHz/Div}} | {{Spec|Span | 200 Hz/Div – 100 MHz/Div}} | ||
{{Spec|Sweep | 1 μs/Div to 10 s/Div ( | {{Spec|Sweep | 1 μs/Div to 10 s/Div (1−2−5), manual, external}} | ||
{{Spec|Resolution bandwidth | 30 Hz – 3 MHz in decade steps}} | {{Spec|Resolution bandwidth | 30 Hz – 3 MHz in decade steps}} | ||
{{Spec|Sensitivity | −128 dBm at 300 Hz to −80 dBm at 3 MHz }} | {{Spec|Sensitivity | −128 dBm at 300 Hz to −80 dBm at 3 MHz }} | ||
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==Internals== | |||
The input signal passes a 0 to 60 dB step attenuator, a 1.8 GHz low-pass filter, and a 3 dB isolation pad before the 1<sup>st</sup> mixer, with a 1<sup>st</sup> LO frequency between 2.095 GHz and 3.895 GHz. At spans of 50 kHz/Div and below, the | |||
1<sup>st</sup> LO (a YIG oscillator) is fixed (stabilized by a PLL) and the 2<sup>nd</sup> LO is swept. | |||
The 1<sup>st</sup> IF filter is 10 MHz wide, centered at 2.095 GHz. With a 2<sup>nd</sup> LO at 2.2 GHz, the signal is mixed to a 105 MHz IF, amplified, filtered again (105±1.5 MHz)and mixed down to 10 MHz (3<sup>rd</sup> LO at 95 MHz). | |||
At the 10 MHz 3<sup>rd</sup> IF, resolution filters (300 kHz L/C, 30 kHz, 3 kHz or 300 Hz crystal filters) can be selected. The detector (discrete log amplifier) and video filters follow. | |||
The digital frequency readout is a DVM ([[Fairchild 3814]]) working off the the YIG oscillator control voltage, not a frequency counter, which is why it needs to be calibrated before use. | |||
Custom integrated circuits used: [[155-0035-00|155-0035-00 quad opamp]], [[155-0042-02|155-0042-02 Miller Integrator]], [[155-0056-00|155-0056-00 Sweep Control]], [[155-0088-00|155-0088-00 Legend Generator]]. | |||
==Pictures== | ==Pictures== | ||