RF Combo

Posted on Feb 5, 2014

The RF Combo (A3016) is a combination of three circuits. Its purpose is to provide circuit boards for Stage Four of our subcutaneous transmitter development. The printed circuit board has the same outline as the RF Tester ( A3014 ). The SAW Oscillator (A3016SO) replaces the A3014SO. This new version uses unconditionally-stable amplifiers and othe

RF Combo
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r improvements. It is the same shape and size as the A3014SO. The RF Spectrometer (A3008C) replaces the RF Spectrometer ( A3008C ). This new version eliminates the poorly-performing SAW filter self-calibration system, and replaces it with a local oscillator output connector that will allow us to calibrate the spectrometer`s local oscillator with respect to a SAW Oscillator reference. It is the same shape and size as the Data Recorder ( A3007C ). The Demodulating Receiver (A3016DR) replaces the A3014DR. This new version uses unconditionally-stable amplifiers in the RF input stages, so as to avoid oscillations provided by the SAW filter outside its pass-band, and by antenna cables. Its IF amplifier cannot damage itself when over-driven. We use attenuators between IF amplifier stages in the hope that these will guarantee stability in the face of limiting gain. We add a low-pass filter to the demodulated output to get rid of the second harmonic of the IF. We add a final buffer to produce a large 50- © output. The SAW Oscillator (A3016SO) works well. We were at first confused by it because it would not oscillate with any or our narrow pass-band filters, such as the 868. 4 ±1 MHz B3570, which we used to produce our reference frequency with the A3014SO. But the A3016SO does oscillate with filters whose pass bands are a few megahertz or more. And when it does oscillate, the A3016SO is stable and robust. We can stop it oscillating...

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