[TenTec] OMNI VI Plus, MMTTY, and FSK

[Dave W7DPW]

There are three ways to do it.

1.) Get rid of the tranny and just use the resistor only, it should
work.

2.) Use an NPN instead of the PNP tranny and wire as you mentioned,
ground base, feed the emitter and take the output from the
collector.

3.) I use the third, use two NPNs  to invert the original tranny.
tranny1, feed base, ground emitter, collector with 12V pullup resistor
to base tranny2,  emitter grounded, collector tranny2 to 6+ FSK..

Dave W7DPW

----- Original Message ----- 
From: <KA5M at aol.com>
To: <tentec at contesting.com>
Sent: Tuesday, January 24, 2006 7:32 AM
Subject: [TenTec] OMNI VI Plus, MMTTY, and FSK


> I used the FSK keying circuit specifically for the OMNI VI Plus shown
on
> http://www.aa5au.com/rttyinterface.html to build a COMM port to radio
interface.
> I used a 2N4402 PNP transistor.  As shown, pin 3 (TXD) of the DB9 comm
port
> goes through a 1K resistor to the emitter.  The base is grounded, and
the
> collector goes to Mark/Space on the rear of the OMNI VI Plus. When I
try to transmit
> RTTY, all I get is a steady tone.  The radio is not being keyed.  (PTT
using
> a 2N4401 NPN transistor work fine, no problem.)
>
> Has anyone built their own transistor FSK and PTT interface and got it
to
> work?  Any suggestions would be appreciated.
>
> 73,
> KA5M, Marsh
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