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TUCoPS :: Radio :: ic3200a2.txt

Icom IC-3200A mods




IC3200A.2

Subject: Fix for IC-3200A used on packet

R:880518/1202z 2985@N4KWB  [Dade EOC - NTS SysOp BBS,FL] Z:33173 
From: N4KWB@N4KWB

                           IC-3200A FIX


FOR THOSE POOR SOULS WHO ARE TRYING TO USE THE IC-3200A ON PACKET HERE IS
HERE IS SOME RELIEF.

THE PROBLEM IS THAT WHEN GOING FROM TRANSMIT TO RECEIVE  THERE IS A DELAY
IN THE RECEIVE AUDIO TURN ON, WHICH IS ON THE ORDER OF 500 MILLISECONDS 
AND MAY BE TOO LONG FOR SOME PACKET SITUATIONS UNLESS EVERYONE HAD THEIR
TXDELAY SET TO 750 MILLISECONDS.

THERE ARE TWO WAYS TO RESOLVE THE PROBLEM. BOTH ARE FAIRLEY SIMPLE.
THE EASIEST WAY IS TO REMOVE THE MUTING ON THE AUDIO P.A. I.C. 

THE INSTRUCTIONS FOLLOW:

1. REMOVE THE COVER THAT HAS THE SPEAKER ATTACHED TO IT 
   (BEING CAREFUL OF THE WIRES)
2. WITH T2. WITH THE FRONT OF THE RADIO FACING YOU, LOOK FOR THE
   AUDIO P.A. I.C. IN     AUDIO P.A. I.C. IN THE RIGHT REAR PART OF THE RADIO NEXT TO
   THE CHASSIS    IT IS MARKED  "UPC2002", LOOKS LIKE A  TO-220
   CASE TRANSISTOR,  AND  HAS FIVE LEADS ON IT
3. IMMEDIATELY TO THE LEFT OF THE  "UPC2002" IS A DIODE  STANDING
   ON END, AND MARKED  "D19" ON THE CIRCUIT BOARD    THIS IS THE
   DIODE THAT MUTES THE AUDIO P.A. I.C. DURING TRANSMIT
4. CUT ONE LEG OF  "D19"  AND THE AUDIO P.A. I.C. WILL NO LONGER
   BE MUTED DURING TRANSM ITHIS IS ALL THAT IS REQUIRED AND MY TESTS HAVE 

SHOWN THAT THE IC-3200A WILL WORK WITH OTHER TNC'S WITH TXDELAY'S SET AS 
SHORT AS 150 MILLISECONDS WHERE BEFORE THIS MODIFICATION A TXDELAY OF ABOUT 
600 MILLISECONDS WAS REQUIRED OF THE STATION TRYING TO COMMUNICATE TO THE 
IC-3200A.
 


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