[amsat-bb] Re: drake 2880

[Edward Cole]

At 02:26 PM 2/23/2010, Jim wrote:
>Has any one used the Drake 2880 downconverter on the air.
>
>
>
>I have 2 of them 1 I did the mod on and one that has not has any thing done
>to it.
>
>
>
>Jim
>
>K7UDG
>
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I have two Drakes that were used on AO-40.  One is converted to 
435-MHz IF and the second unmodified runs with 123-MHz IF.  I feed 
both with a MKU-232A2 preamp directly connected to a 6-1/4 turn 
helical feed in front of a 85cm (33-in) offset feed dish.  I have not 
re-installed my Drakes but the dish/preamp are ready for use.

The Drakes do not have very good noise figure (~7 dB) so a low-noise 
preamp is mandatory.  The db6nt preamp has 0.6 dBNF with 40-dB gain, 
easily able to feed both Drakes thru a coaxial tee.

I also have a DEMI 2400-MHz preamp which I am thinking of feeding 
with a patch antenna.  I am thinking that the patch should provide 
ample gain for S-band Leo satellites.  The two antenna/preamps will 
be connected to the Drakes via a cross-over relay (not yet installed).

I will need auto-tracking/tuning for S-band operation on Leo's.


73, Ed - KL7UW, WD2XSH/45
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