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ZL1ABS > TNC2 09.10.07 02:24l 46 Lines 1515 Bytes #999 (0) @ WW
BID : 091047ZL1ABS
Read: OE7HNT GUEST DK5SG OE3GMW DL9NDQ
Subj: MFJ TNC2 DIP switch trouble
Path: DB0FHN<DB0MRW<DB0PV<OE6XHG<OE6XPE<DB0RES<ON0AR<ZL2BAU<ZL1UX<ZL1AB
Sent: 071009/0100Z @:ZL1AB.#06.NZL.OC #:2392 [AUCKLAND] FBB7.00i $:091047ZL1ABS
From: ZL1ABS@ZL1AB.#06.NZL.OC
To : TNC2@WW
TNC-2 DIP Switch troubles
After a frustrating morning trying to get some used MFJ TNCs to operate on
VHF 1200 baud Packet, the answer was the DIP switches on the back!
The symptoms were hard to understand. The panel LEDs operated correctly.
The PC could communicate with the TNC in terminal mode or KISS mode. The
baud rate was OK. The DCD LED would light on incoming signals, but nothing
received was ever seen on the screen. Nothing was recorded in the MHeard
list either.
Changing the audio level did nothing.
Comparing the DIP switches on the back of the MFJ1270C & MFJ1276 (I had
two used TNCs with exactly the same trouble), to another MFJ TNC that
operates correctly, the "Radio" section of the rear DIP switches was set
differently. Changing the DIP switches to the correct setting cured the
trouble immediately.
Looking at the back panel of the MFJ1270C & MFJ1276 (has PACTOR as well as
regular AX25) the DIP switches are a red block numbered 1 to 8 left to
right.
DIP switches 1 to 5 are "TERMINAL" for the serial communications baud
rate. As I am using 9600 baud from TNC to PC the switches are:
1, 2, 3, 4 UP
5 DOWN.
DIP switches 6 to 8 are for "RADIO"
The correct setting for VHF use is:
6 UP
7 DOWN
8 UP
It was the "RADIO" DIP switches 6,7 & 8 causing my no-go problem.
The VHF/HF button (on the right hand side of the rear panel) also has to
be OUT for VHF operation.
My "investment" in used TNCs might be worthwhile now.
73 de Michael ZL1ABS
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