[FADCA] RFDCD on Spirit 2 TNCs

[bud thompson]

----- Original Message ----- 
From: "Chuck Hast" <wchast at gmail.com>
To: "Florida Amateur Digital Communication Association" 
<fadca at mailman.qth.net>
Sent: Monday, December 06, 2004 09:49
Subject: Re: [FADCA] RFDCD on Spirit 2 TNCs


> On Mon, 6 Dec 2004 08:57:40 -0500, bud thompson <budt at cfl.rr.com> wrote:
>> Pin 5 on the standard TAPR 5-pin TNC connector is the RF DCD - or 
>> external DCD for the purpose of inhibiting the TNC TX when an external 
>> DCD line is connected to pin 5.  I can't find any reference in the 
>> Sprint, Spirit, or Tiny-2 technical manuals if this line must go to 
>> ground or go high to inhibit TX.
>>
>> In the Kantronics 1200b connector Pin 2 of the 9-pin connector is used as 
>> the external carrier detect.  When pin 2 is grounded, TX is inhibited.
>>
>> Is the logic the same for  the Paccomm TNCs?
>>
>> That would be 'logical.'
>
> Yes, that would. They are TNC-2 clones I will have to see if I can run 
> down the
> TNC-2 spec, but the quick way is just to pull the line to ground and see 
> if the
> DCD LED goes on. Will do that when I get home this evening.
>
> I think that the Spirit may have a jumper in there to invert the DCD
> as there are
> situations where that is needed. The newer Tinies may have it also. 
> Memory is
> failing, I hope the rest does not follow suite.
>
>
> -- 
> Chuck Hast


Yes, in the Spirit/Sprints the jumper is SP10 (a solder one I think).. the 
trouble is I don't want the modem DCD inhibited - just want the external one 
added... That is I need the 9.6kb TNC to be TX inhibited when either the TNC 
has a valid on-channel input signal (normal DCD) or when there is an 
external indicated of DCD.

thanks
bud