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Date: Wed, 19 Dec 2018 23:24:41 +0100
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: LF: Ebnaut receiver frequency stability qustion
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Hi Paul,

Am 19.12.2018 18:57, schrieb N1BUG:
> Hi Stefan,
>
> Thanks for showing us your TX converter circuit. That is a bit more
> complicated than I was expecting which goes to illustrate my point
> about why diagrams are so important. I thought you meant to use a
> simple DBM mixer with a LO. I see I was wrong about that.
>    
Yes but there you don't need to build high Q band filters. It is just 
some Rs and Cs and logic ICs...

> I can build this. But how do we connect the Ublox LO?
I don't know yet how the output voltage of the modele looks. Is it 3.3 V 
or 5 V? Maybe some kind of buffer will be needed.

>   Remove the
> 74HC4060 and connect the Ublox to the 74HC4052 CLK pins through a
> capacitor?
>    
The Ublox would be connected to the 500 kHz input of the 74HC74. Not 
through a capacitor, i would connect it directly.

> Do the capacitors in the circuit need to be any special type? It
> seems some of them might need to be quite stable?
>    
I took normal ceramic Cs and foil Cs, just what i found from the junk box.

73, Stefan