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[TenTec] Argosy Mod Question

To: qrp-l <qrp-l@mailman.qth.net>, tentec@contesting.com
Subject: [TenTec] Argosy Mod Question
From: Shawn Upton <kb1ckt@yahoo.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 11 Jun 2006 18:03:48 -0700 (PDT)
List-post: <mailto:tentec@contesting.com>
I finally am getting around to modding my Argosy I
with the mods listed on the unofficial pages.  I
couldn't find the diodes listed, but made some
substitutions:

5082-2800: these were for the mixer diodes.  I used
1N5711, with no other changes to the mixer.

5082-3081: these were for the diode switches (D10 and
D11).  I'm using MPN3404--but I'm also planning to
change D1 and D7, as they are also in the RX signal
path.  I'll also boost up D7 current to the same
22mA-ish as the others, probably via a 100uH inductor
across R33.

Looking at the datasheets, it appears that the MPN3404
is a lower on resistance at low current than the
specified HP diodes at high current.  And, strangely
enough, the Argosy already uses the MPN3404's in the
TX path.

So, the question is, anyone know why the author didn't
use MPN3404's?  The HP's slightly better?  It's kinda
moot, as I couldn't find the HP's and the iron's
cooling off now; but my inquiring mind wouldn't mind
knowing.

Thanks.


Shawn Upton, KB1CKT

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