Modifications for the Kenwood TM-255

Picture(s) of Kenwood - TM-255

19-07-1998 Solution 9k6 TM255/455 English language
06-08-1999 Mods for the Kenwood TM-255E English language (1 Kbytes)
 View all modification in one click. This can be a very big file.!! (2 Kbytes)

19-07-1998
Solution 9k6 TM255/455

Dear OM's

This is what I found a service technical report from Kenwood acc. TM255 and TM455 9600bps Date November 8, 1994

SUBJECT: Countermessure against modulation during packet 9600bps operation.

Phenomenon:
A trouble modulation malfunction during packet 9600bps operation was found in the manufacturing process even trough there in input in the DATA terminal.
Pay heed to this trouble in replacing the analog switch IC13.

Cause:
This trouble is cuased by variation in the analog switch IC13.
Even if the 9600bps SW Tr.(Q20:DTA124EK) has been turned ON, the analog switch IC remains unstable.

Counter messure:
We decided to raise the analog switch IC13 voltage while the 9600bps SW TR. (Q20:DTA124EK) is in action by changing the chip resistor R117 in the TX-RX-unit of TM455A/E and of TM255A/E.....etc.

R117=10K to be replaced with 3K3


So if you have problems with those two say to your dealer to ask for SERVICE TECHNICAL REPORT No. B510-94-081E page 1/2 and page 2/2

73's DE PAT KE6MIQ

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