[amsat-bb] Drake 2880 modiication results

["wc0y" <wc0y@xxxxxxxxxxxxx>]

Modifications to my Drake 2880 are nearly completed.  These are the gain and
noise figure results that I measured after different stages of modification.

Results after the crystal was changed for 145 MHz IF, the three legs of the
S-Band filter were lengthened, and the two red IF coils and their parallel
capacitors were removed:

Gain = 19.8 dB, Noise Figure = 5.44 dB at 145 MHz

Results after capacitors were paralleled with the chip caps on both sides of
the green IF coil:

Gain = 23.0 dB, Noise Figure = 4.96 dB

I then replaced the first LNA transistor stage with an MGA-86563 PHEMT with
these results:

Gain = 38.7 dB, Noise Figure = 1.90 dB

The MGA-86563 device has the same performance at 2400 MHz as the MGA- 88576
that others have used.  However, it is in a 6-pin miniature dual-in-line,
surface mount package.  It can be mounted using the original pads by
rotating slightly to fit. This modification turned out to be a very hard to
do.  You will need many tools like tweezers, small-tipped soldering irons
(two of these help), a  magnifier lamp, and lots of patience if you decide
to do this one.

Thought I would pass these results on to help others starting to modify
their Drake.

Happy modifying!

73,
Ward - WC0Y

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