[hpsdr] Preselectior switching

[Giancarlo Moda]

Hi Eric,

thanks for guiding me on the upload.

I have loaded the file on:

http://www.hamsdr.com/personaldirectory.aspx?id=524 

Enjoy the reading and the possible use of the idea.

73

Gian
I7SWX


--- Eric Ellison <ecellison at gmail.com> wrote:

> Gian
> 
> You can upload files to http://www.hamsdr.com/  Go
> to Public Uploads and
> create a folder if necessary. 
> 
> After uploading, copy the link to the files into
> your message.
> 
> See my Teamspeak message next.
> 
> I'm sure many others are interested! 
> 
> Thanks
> Eric - AA4SW
> 
> 
> -----Original Message-----
> From: hpsdr-bounces at hpsdr.org
> [mailto:hpsdr-bounces at hpsdr.org] On Behalf Of
> Giancarlo Moda
> Sent: Saturday, March 17, 2007 6:23 AM
> To: Graham Haddock
> Cc: HPSDR Group
> Subject: Re: [hpsdr] Preselectior switching
> 
> ***** High Performance Software Defined Radio
> Discussion List *****
> 
> Hi Graham,
> 
> the system will not accept the attachements.
> 
> certainly...here it is.
> Enjoy the reading
> 
> 73
> 
> Gian
> I7SWX ... the one of FST3125...hi
> 
> --- Graham Haddock <grahamh at verizon.net> wrote:
> 
> > Gian:
> > 
> > I didn't see the attachments.
> > 
> > Please send them direct to me at my email address.
> > 
> > Thank you,
> > --- Graham / KE9H
> > 
> > Giancarlo Moda wrote:
> > > ***** High Performance Software Defined Radio
> > Discussion List *****
> > >
> > > Hi all,
> > >
> > > for a receiver front end preselector I would
> > suggest
> > > to look at the solution used in the STAR,
> Software
> > > transmitter and receiver, by G3XJP. The
> switching
> > > elements are FST3125 and FST3126 as used in the
> > H-Mode
> > > Mixer.
> > > No IMD problems and expensive relays and or PIN
> > diodes
> > > purchase. Fast switching, low insertion losses
> and
> > > valid filetrs separation.
> > >
> > > I am attaching a copy of circuit diagram and
> > article
> > > extract from RadCom.
> > >
> > > I have added in copy VK6APH, KK7P and N8VB as
> they
> > > will receive the attachment and then they may
> > decide
> > > to load it in file directory.
> > >
> > > 73
> > >
> > > Gian
> > > I7SWX
> > >
> > >   
> > >> From: hpsdr-bounces at hpsdr.org 
> > >> [mailto:hpsdr-bounces at hpsdr.org] On Behalf Of
> > Henry
> > >>     
> > > Vredegoor
> > >   
> > >> Sent: vrijdag 16 maart 2007 5:48
> > >> To: hpsdr at hpsdr.org
> > >> Subject: Re: [hpsdr] Preselector schematic.
> > >>
> > >>     
> > >
> > >   
> > >> Two observations:
> > >>
> > >> - There must have been a design issue for using
> > >>     
> > > relays on the 
> > >   
> > >> LOWER BANDS;
> > >> maybe also the lower (zero) resistance of the
> > relay
> > >>     
> > > contacts
> > >
> > >   
> > >> - The are having the relays switching a (small)
> > >>     
> > > current on 
> > >   
> > >> purpose, I think
> > >> to keep the contacts clean, keep the resistance
> > low
> > >>     
> > >
> > >
> > > After studying the schematics a little more, I
> > think
> > > it prevents the 
> > > (other)
> > > PIN diodes from conducting, stopping the HF from
> > all
> > > not selected 
> > > filters.
> > >
> > >
> > >
> > >
> > >
> > >  
> > >
> >
>
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> > >   
> > 
> > 
> > 
> 
> 
> 
>  
>
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