Of course you're right, Jim. Instead of a dc voltage,
it sends a ground, after biasing Q-11 to conduction.
Q-15 has a voltage present on the base, biasing
it to cutoff until that voltage is lowered by a ground
on the TXEN jack.
My error. But - the result is the same whether
it uses a voltage, or lack of a voltage.
The reasoning for this circuit is for the OMNI to inform
the amplifier that it is now ready to transmit. The amplifier
is supposed to take this information, make the transition
to a transmit condition, then send a signal in the form
of a ground, back to the OMNI, which then starts emitting
rf. The timing is therefore provided by the amplifier and
actually shortens the dash or dot by the time necessary
to make the transition. In the case of RJ-11 relay rigs, that
is about 6 milliseconds which is not a problem. Slower
relays could "thin" the cw signal significantly.
Thanks for making me get out the manual, Jim.
From: Jim White <firstname.lastname@example.org>
To: email@example.com <firstname.lastname@example.org>
Date: Sunday, September 20, 1998 3:43 PM
Subject: [TenTec] TX out and TXen
>According to my Omni 6+ manual, TX out generates a "closure to ground'
>transistor Q11) - My Centaur takes this "low" inverts it, and uses it to
>apply base Bias to a transistor.- this closes a relay, (and turns on the
>Amp. ) the relay closure (to ground thru 47 ohms) is sent back to 'TX
> Looking at the Omni 6+ schem. this is what you get if you leave the
>"shorting" plug in place between "TX OUT and TX EN"-notice "TX EN" has a
>"Bar" over it--it wants to see a "low" to ground (thru 47 ohms)- before
>allowing the Omni to transmit......this is to eliminate "hot switching".
>Your Alpha must be placing a CONTINUOUS "low" on "TX EN" (or a
>oltage) -this must be keeping the omni on Xmit..
> What does the Alpha "c" output consist of?? --'73 JIm W. K1EXE
FAQ on WWW: http://www.contesting.com/tentecfaq.htm
Administrative requests: tentec-REQUEST@contesting.com