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Fw: Drake 2880 additional mod



Several people kindly wrote me that the link to the photo showing Drake 2880
mods that I provided does not work.  I have been working on a web page that
has the photo and more details.  Please try:

http://communities.msn.com/wc0y

73,
Ward - WC0Y


----- Original Message -----
From: "wc0y" <wc0y@email.msn.com>
To: <amsat-bb@AMSAT.Org>
Sent: Tuesday, February 20, 2001 10:21 PM
Subject: [amsat-bb] Drake 2880 additional mod


> I did one more mod to my Drake 2880 and will now quit while I am ahead.  I
> had reported a gain of 38 dB and a 1.9 dB noise figure achieved by
replacing
> the first amplifier stage with a MGA-86563 MMIC and doing the other mods
> described at the G3PHO site.  The next step was to protect this IC from
> static on the input connector without loosing performance.  I plan to use
> this converter with a helix that is not DC grounded.
>
> A photo of my modified input circuit can be found at:
> http://www.msnusers.com/wc0y/files/LNA.jpeg
>
> You will see two chip inductors, one in the MMIC bias circuit, and one at
> the input connector, from the input trace to ground.  The chip inductors
> have blue markings.
>
> These inductors are Coilcraft 0805CS-220X_BC part number.  I chose this
one
> because it is designed to have a series resonant frequency (SRF) around
2400
> MHz.  It is a wire-wound chip inductor, so it should help with static
> discharge.  I am happy to report that placing it across the input circuit
to
> ground had no measurable effect on gain or noise figure.
>
> Coilcraft has a good web site at www.coilcraft.com, and they do direct
> sales.
>
> If you downloaded the photograph, you will see the MMIC placed between two
> "huge" eyelets that I inserted to get a low impedance path to the ground
> foil on the underside.  These eyelets are 0.055 inches in diameter on the
> body, and 0.10 inches in diameter at the collar that is visible.  That
shows
> how tiny the MMIC IC is.
>
> Hope this helps some of you with your plans.
>
> 73,
> Ward - WC0Y
>
> ----
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