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Drake 2880 Modifications



The recent Amsat-UK colloquium at Surrey University saw some extensive testing
and subsequent modification to the popular Drake 2880 Downconverter.

Three modifications were finally adopted which resulted in a steady decrease
in noise figure and increase in conversion gain:

1)  Addition of two 10 cent capacitors to the I.F.     +5dB gain   -1.3dBN.F.

2)  Extending  image filter lines

3)  Change front end device to MGA86576  Mod-Amp.

The final result was a converter with a noise figure of 2.16dB and a
conversion gain of  31dB.

Full details of the modifications are detailed at the following URL.

     http://www.qsl.net/g3pho/drake2.htm   (The World above 1000 MHz)

If you don't feel comfortable changing GaAs FETS have a look at the site
anyway as the modifications detailed in QST still leave the I.F. tunedto 300
MHz.

MGA86576 devices are available in the USA from Down East Microwave.
In the U.K. a kit of parts is available for £6.15 inc. from G0MRF.

See you on P3D!


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