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RE: Getting more gain without a solid dish....



With such a system, you must use a common local oscillator supplying the two
converters.
If each converter uses its own oscillator, you'll never get a stable phase
relationship between the two IF signals.

Jean-Louis F6AGR


> -----Message d'origine-----
> De: Al Lawler [mailto:alawler@us.oracle.com]
> Date: mardi 24 juillet 2001 13:41
> À: amsat-bb@AMSAT.Org
> Objet: [amsat-bb] Getting more gain without a solid dish....
> 
> 
> 
> 
>   After my first night on ao-40,  I can see that
> despite not being the "poorest kid on the block"
> recieve-wise, I could definately do with some 
> more antenna gain.
> 
>   My current setup is a 24dbi(linear) gain bbq
> dish with a DEM preamp and drake converter with
> the easy mods.
> 
>   Using the Ao-40 spreadsheet, I see that the
> only thing I can really benifit from improving
> is the antenna itself.  (And possibly a few db 
> more preamp gain, but not much.)
> 
>   Going to a solid dish with a helix feed isn't
> an option, due to wind/snow  resistance and weight
> considerations.
> 
>   What I'm thinking of doing is to simply add
> a second BBQ dish, cross polarized with respect
> to the first one), with its own preamp/converter 
> (another dem/drake), then connecting the (144mhz)
> outputs of both drakes to the feedline via  a 2-meter
> "circular" phasing harness.  (I.e. the same
> harness used to get circular polarization out of
> 2 yagi's.)  The idea is to be able to generate
> a circularly polarized antenna (with more capture
> area), without having to manufacture a precision
> phasing harness for 13cm.
> 
>   Does anybody have any comments on how well this
> is likely to work?
> 
>   -al
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