[OZAPRS] Help with MJF-1270b and UI-View32

Phil Kern vk5zey at kernit.com.au
Sun Dec 30 21:57:02 EST 2012

Hi Ray, see below..


From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Ray Wells
Sent: Sunday, 30 December 2012 8:48 PM
To: ozaprs at aprs.net.au
Subject: Re: [OZAPRS] Help with MJF-1270b and UI-View32



Things I would check .....
1. Is the comport speed set correctly to match the settings in the
application. e.g. 9600

>>Yes, all correct there..

2. Is the radio data rate set correctly to 1200bps - DIP switches 6, 7, 8.

>>Yes all correct there..

3. Is the HF/VHF switch in the out position for VHF

>>Yes set to VHF

Going a little deeper, I'd check the audio into the TNC from the radio to
see how close the two tones are to being the same level. The Exar decoder
chip in the MFJ1270B is particularly intolerant of the high tone (2200Hz)
being lower in level than the low tone (1200Hz) and will refuse to decode if
the levels are too different. The TNCs need about 200mV p2p for reliable

Have you used a terminal program to try to talk to the TNC. You should, at
very least, see the TNC message when the TNC is powered up. This can confirm
comport speed, etc. I don't know what the latest terminal program is for
Windows (I use Linux) but hunt around. If you can talk to the TNC with the
terminal program you are well placed to conduct various tests as suggested
by Gordon vk4vp.

>>Yes, used PuttyTel and connected and I can communicate to the TNC.

I have 8 MFJ1270B TNCs (all bought second hand) that have seen service at
HF, VHF and UHF and I must say I've never had a reason to doubt the tone
frequencies on any of them, but ........

>>Hmm, used to work perfect, but has been packed away.


Thanks for your help 


Phil ZEY

Ray vk2tv

On 30/12/2012 3:09 PM, Phil Kern wrote:

Hi Guys,


Recently dusted off an old MJF-1270b which I used to use with 'packet' many
years ago.


Now trying to configure this with UI-View32. I'm unsure about the config
within the Comms Setup Area.

It appears to be connected on the default setting. Just can't  seem to
decode anything on the terminal screen.


Have followed the Config Guides on aprs.net.au Aprs via Internet seems to
decode correctly.


Any help or pointing me in the right direction, would be greatly






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