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Re: Alinco $88 HT @ 9600 Baud



Bob, I would like to try this mod.  Is it the Alinco DJ41T?


>From: Bob Bruninga <bruninga@nadn.navy.mil>
>To: amsat-bb@AMSAT.Org
>CC: TAPR APRS Special Interest Group <aprssig@tapr.org>
>Subject: [amsat-bb] Alinco $88 HT @ 9600 Baud
>Date: Wed, 8 Sep 1999 12:04:59 -0400 (EDT)
>
>Regarding using the $88 ALinco HT on 9600 Packet downlink:
>
>Good news:  The Disc output is easy to get to, and looks linear.
>             Its easy to mount a SIP header pair through the side
>             of the case for easy interfacing.
>
>Good news:  The sensitivity is as good at 436 for satellites as 446 MHz
>
>Bad news:  After adding an external ANtenna connection, I measured the
>            receive sensitivity at -116 dBm.  That's 6 dB worse than my
>            Kenwood THD7 (with built in 9600 baud TNC) but still usable
>            with a preamp.
>
>The Kenwood can get good data with a 3 element handheld beam.  The alinco
>will need more elements or a preamp to get to the horizon.  But still good
>for briefcase portable on the 9600 baud birds.  The 5 Khz steps seemed
>adequate to keep the pattern on a scope  clean.
>
>I am not configured for PACSAT Protocol and was only viewing packets on
>a dumb terminal screen.  So I dont know how many packets I got.  Saw lots,
>but doubt it was 100%...
>
>DISC OUTPUT:  THe DISC output is easy to find.  Open up the back and right
>in the center, just above the VCO metal box is printed "SQ" and "RT3".
>The chip capacitor to the left of the "RT3" is a blocking capacitor
>between the discriminator output and the Squlech POT just above it.  The
>end closest to the "RT3" is the DISC side.   I broke off two pins of a SIP
>header socket and melted it slightly into the lower case just above the
>VCO can.
>
>The lower pin goes to the DISC, and the upper is soldered to the VCO can
>as ground.  This also provides solid mounting for the plastic header.
>Then I cut out a matching slot in the back cover so that it fits back on.
>
>The result is a flush mounted barely noticible 2 pin SIP socket into which
>you can plug your 9600 baud TNC.
>
>I visually observed DISC noise components no shorter than  80 us which
>sure enough equates to 12.5 KHz.  So this is a narrow receiver... and
>others may be able to draw conclusions as to the overall viability of this
>radio for 9600 baud use.
>
>For an external antenna, there is a SIP header on the board with 2 pins
>just for this purpose.  I soldered a short 3 foot pigtail with a BNC on
>the end to this point, just long enough to reach a handheld antenna.
>Sorry, I dont have any more time for further testing, but it appears as a
>low cost entry into the 9600 baud downlinks.. (How many are there now? 5?)
>
>I'll bring it to the AMSAT COnference
>
>de Bob, WB4APR
>
>
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