[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Fw: Drake 2880 additional mod



Looking at your pix you can trim out the little shorting bar on the input
"hairpin loop" and see a bit more gain. Gives you a bit better match at 2401.

wc0y wrote:

> 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
> >
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home