Re: BITX-40

Arv Evans K7HKL <arvevans@...>
 

Rudd PE2BS

Thanks for the help.  He needed information that I could not provide.

Arv K7HKL

On Sun, 2005-11-06 at 19:20 +0000, Ruud Jongeling wrote:
Hello Uelson and Arv,

In my BITX20 and my new BITX8020 (IF-9MHz, not ready yet) I used FT37-
43 with 13 turns trifilair of bifilair, 0,3mm for all transformers in
the mixer, the demodulator and the driver stage.
In my DRM radio (3995 kHz, direct conversion) I used FT23-72 with 10
turns, trifilair, 0,2 mm in the mixer.
I have no experience with FT37-61.

73
Ruud
PE2BS

--- In BITX20@..., Arv Evans K7HKL wrote:
>
> PY2UAT
>
> Since I used Farhan's air-cored toroid idea (small plastic rings as
coil
> formers) I am probably not the best person to answer your question
about
> which ferrite type toroid core material is best for your
application.
> Possibly some other member of the BITX20 forum could answer this
> question?
>
> As to wire size, the currents involved are rather small, so the real
> question seems to be how small can the wire be and still be
reasonably
> easy to work with in winding the transformers.  For my plastic core
> transformers I used #26AWG which is approximately 0.404 mm or
British
> SWG-29.   
>
> The number of turns will depend to some extent on which ferrite core
> material you use.  There are published tables which show the number
of
> turns required for a specific inductance for each type of ferrite
mix.
>
> For the non-resonant transmission-line transformers used in the
mixers
> it is usually adequate to have between 7 and 11 turns per winding
if you
> are using ferrite based toroid cores.  I am using 16 turns with my
> air-core transformers.
>
> Arv - K7HKL
> >
> > 
> > Please, I am constructing the BITX-40 v3 version of Rahul, but I
want
> > to construct it (T1, T2 and T3) with FT37-61 or FT37-43 which of
the
> > two would be better? And how many wire returns AWG would be
necessary?
> > 
> > Thank You!
> > Vy's 73
> > Uelson de Almeida Toyama - PY2UAT
> >
> >
> >
______________________________________________________________________
> > Yahoo! Acesso Grátis: Internet rápida e grátis.
> > Instale o discador agora!
>








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