[minima] Re: Parts list spreadsheet, still work in process

  • From: Jeremy Chase <jeremychase@xxxxxxxxx>
  • To: minima@xxxxxxxxxxxxx
  • Date: Sun, 16 Mar 2014 09:37:55 -0400

Thank you Thomas and Sandeep for the detailed answers and for doing so much
legwork. I'll be updating the spreadsheet today to incorporate your
information.
>>    1. Can the 3u inductor near T3 be the same type as the inductors in
>>    the filter?
>>
>> I guess you are referring to the inductor labelled "RFC" on Farhan's
> schematic. Farhan said: "The RFC is 10 turns on FT37-43" According to
> toroids.info, that is 35 uH.
>
> So no you cannot use the same inductors. And where did you get the value
> 3uH?
>


Jeremy & others...

3 uh is not critical it can be any thing from 2.2 uh to 10 uh (
depends on XTAL )
can be wound on dumble core, airwound, 3.3uh RFC readily available 1/4
CFR size RFC, however best stability will be with if on metal dust
core...
rest variable  Pf trimmer will take care off...
those wound on ferrite increases inductance when warm-up...

bring your hand near to that RFC ( don't touch ) & observe if changes
BFO frequency ...

it's just to pull down XTAL ( for USB, but here opposite with MINIMA )
also depends on Xtal threshold, before it goes unstable.
here I use 2 separate Xtals, coz those matched goes in ladder,
previously also used 22uh but that is not recommend...

-------------------------------------------------

There's also RFC on emitter on Q5 near triflar T 3,
that it's value is also not critical but bandwidth dependent on center
of HF spectrum.
since it's broadband it could be wound on ferrite materiel meant for
HF or VHF ( use smaller size ),
8~15 turns on recycled Guenella transformer will be fine...

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