Category Archives: mixer

Bitx20 VFO mixer & VFO

  Back to the Bitx. I spent some time doodling and staring at the VFO mixer on paper (see above).  I redrew the trifilars in a way that made more sense to me. I think I got the gist of … Continue reading

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Some test equipment hiccups

This is where my lack of serious “bench time” in my life is probably biting me a bit. I discovered some weirdness tonight between my scope and signal generator.  Keep in mind I owned neither of these instruments 5 months … Continue reading

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Trifilar trauma & construction styles

I decided to turn my focus to the trifilar transformer.  I’ve never really become familiar with these but it looks like the one used in the Bitx mixer is basically a 1:2 turns ratio transformer with a center-tapped secondary.  Maybe … Continue reading

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More mixing madness!

A couple of new insights today. First, I went back and looked at Bill’s Soldersmoke example of a more intuitive-style mixer.  He discussed a circuit from an article by Leon Williams, VK2DOB, published in SPRAT (G-QRP club quarterly journal).  I … Continue reading

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Mixing math details (diode)

Here’s the part two in the mixer math series. I decided to devote some time to trying to document the basic analysis of a diode mixer.  The development of this material follows closely a kind of classical analysis that is … Continue reading

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The math of mixing (diode)

I haven’t had much time this week but I managed to squeeze in some time to go through the math of mixing as applied to a diode.  I’ve done this exercise before (a few years ago) but it had been … Continue reading

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Playing with amplifying and tidying up

I sort of reverted back to playing with the amplifier circuit I’d built last month, the little common emitter one with about 10mA collector current on it and about 10 dB gain.  I built it ugly style on a chunk … Continue reading

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