Softrock RXTX Dividers – Stage 3

The dividers stage takes the local oscillator’s signal and divides it by four, producing two output signals that are said to be ‘in quadrature’. This means they are out of phase with each other by 90 degrees.

The trickiest part of this stage’s construction was soldering in U9, a 74AC74 SOIC-14 SMT that has fourteen small pins (or legs). And even though I took great care soldering them onto their respective pads using flux and a very fine soldering iron, when it came time to test if all was okay, the readings I obtained suggested otherwise. So it was out with my more powerful iron (with a larger tip) and with care, the re-soldering exercise produced near perfect readings on my DMM.

Next on the agenda was something I had been waiting for with anticipation: the frequency output test.

To accomplish this I would need my Hantek 6022BE USB DSO, and both probes.

This is what I observed.

2016-04-30

As can be seen, the two signals are 90 degrees out of phase.

Next to do is to build the RX Op Amp.

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