Re: Help with a different take on a homebrew uBitx #homebrew


If interested in more power and a lot more on the rechnical side of each stage, I can recommend you a book for just that.

On Tue, Mar 2, 2021, 8:57 AM Rafael Pinto [PU1OWL] <rafaelgcpp@...> wrote:
Hello folks

One of my dream projects would be to construct a transceiver myself, and the uBitx is pretty close to what I imagined building, and although I am an PhD in electronics engineer, I have no experience whatsoever in RF design, so I humbly come here to ask for advice (especially from Allison)!

I am planning on building a homebrew uBitx, but I would like to improve the noticed shortcomings on the gain and IF stages, and maybe add AM/FM.  So my questions:

1) Would having the amp stage (Q90) split into two lower gain amplifiers be a better choice?
2) How could I implement an ALC in that case? A controlled attenuator between those amp and predriver stages?
3) Would adding one more IF amplifier/filter stage be advisable?
4) A voltage controlled attenuator in between IF stages would be a good place for AGC/ALC?
5) BJT of FETs?
6) Using this "TIRA" topology for the IF amplifiers be a bad choice? Rephrasing: are common base amplifiers a worse choice?
7) Building modules in different boards and connecting them with RG174 and connectors is a bad choice? I would like to be able to rebuild, for example, an IF amplifier if needed...

If any of this has already been discussed, could you point to the topics? With the search I tried, too many results were returned and none actually pointing to the right direction...


Rafael Pinto

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