Modifications for the Kenwood TM-321
TM-321A Mars/cap mod
To give the TM321 tx coverage from (142 0r 143, don't remember which) to
151.995 mhz, remove the top cover.
Look for a loop of wire comming from the display area (the board with the CPU)
and going right back.
Cutting this wire and then doing a CPU reset is all you need to do.
Takes about 2 minutes. Be sure that the ends of the wire don't short to something.
TM-321A Weak mic audio fix
A quick and dirty fix for the knwd tm231a low mic output: knwd
comes out with a fix which is to bypass r 63 (3.3K). R 63 and r64 form a
voltage divider at the input to the mic amp. R63 is on the bottom of
the rig. With the bottom cover off and the front of the rig facing you,
locate the mic amp board 3610 which stands vertically off the
mother board. Follow the 3rd pin from the left to r63. A jumper here
gives the tx audio a nice boost. Be sure to readjust the dtmf output
in the mic (the only pot in the mic).
TM-321A Mod to Squelch thw audio at mic pin 6
The following is an easy mod to squelch the audio at mic pin 6 for tnc's
Without true dcd: obtain from kenwood a 2sd1757(k) (surface
mount transistor). Install emitter to mic pin 8, collector to
mic pin 6, and jumper from base to the unused pin on connector
202. Using the unused pin rather than running the jumper to the
mother board preserves the plug in feature of the front panel.
Connect one end of a 4.7K resistor (i used a 6.8K) to the
mute line (ic 5 pin 7), and connect the other end to the unused
pin of connector 4, which mates with connector 202. This new
circuit is a close copy of the af mute circuit that squelches
the rx audio at the speaker. It works perfect with my paccomm
micropower 2. The hardest part of the mod is removing the
locking ring around the mic connector. I used a modified table
fork! good luck.
Packet mod for TM-321
8 Nov 89
From: rfc@briar.philips.com (Robert Casey)
The following is an easy mod to squelch the audio at mic pin 6 for
tnc's
Without true DCD: obtain from Kenwood a 2SD1757(K) (surface
mount transistor). Install emitter to mic pin 8, collector to
mic pin 6, and jumper from base to the unused pin on connector
202. Using the unused pin rather than running the jumper to the
mother board preserves the plug in feature of the front panel.
Connect one end of a 4.7 K resistor (i used A 6.8 K) to the
mute line (IC 5 pin 7), and connect the other end to the unused
pin of connector 4, which mates with connector 202. This new
circuit is a close copy of the af mute circuit that squelches
the RX audio at the speaker. It works perfect with my paccomm
micropower 2. The hardest part of the mod is removing the
locking ring around the mic connector. I used a modified table
fork! Good luck.
Go Back To The Kenwood Mods Page
Go Back To The Main Modifications Page
Go Back To The CB / HAM Radio Main Page
Go Back To The Main Home Page
Copyright © The Defpom 1997-2008
https://www.radiomods.co.nz/