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Re: TNC Question



On the older MFJ TNC-2 clones, two manufacturers of DIP switches were
used.  The RED dip switches are OFF when down.   The BLACK dip switch is
OFF when up!!!  There is no combination in which two ON positions are
need to obtain a given baud rate.  Very confusing indeed!   Cliff K7RR

On Tue, 9 Mar 1999, Paul Williamson wrote:

> At 09:41 PM 3/9/99 -0500, you wrote:
> >My question:  How do you set the terminal baud rate?
> >I downloaded the MFJ manual from their web site, but the dip switch
> >settings in there DO NOT WORK. 
> 
> If that's so, then the previous owner must have made bizarre
> modifications to the hardware. Look inside and see if you can
> see any evidence of that.
> 
> Also, make sure you're using the switches right.  On my unit,
> "on" is *down*.  If in doubt, try both ways.
> 
> >I'd guess that at some point they changed the algorithm for setting
> >terminal baud rate...
> 
> The terminal baud rate is set directly by hardware.  That's why
> it's a DIP switch.  There's no way software could change that.
> 
> If you have the whole manual, you can see this in the schematics.
> U1 generates a bunch of baud rate clocks, and the DIP switch
> just gates one of those clocks to the serial I/O chip.  Obviously
> the rule that only one DIP switch should be "on" makes perfect
> sense with this circuit.
> 
> 73  -Paul
> kb5mu@amsat.org
> 
> 
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