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Message ID: 1226     Entry time: Tue Sep 15 11:39:02 2015
Author: Federico 
Type: DailyProgress 
Category:  
Subject: Local Oscillator board 

[Federico, Gabriele]

We decided to downconvert the "broadband" output of the ultrasonic microphones (the ones actually sampled at 64k) using Double Balanced Mixers and a Local Oscillator.

In order to have the cleanest possible L.O. signal, we built a breadboard with a 5MHz TTL xtal oscillator (model MX045-3C-5M0000) followed by two 74LS90, each dividing x10.

The output of the last 74LS90 (=50kHz) is sent to a power buffer (BUF634), then splitted in two 50 ohm signals to drive the L.O. port of the mixers with about +7dBm level.

The next step wiil be to complete the setup adding D.B. mixers on the bench

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