Tim Randa writes...
> Can someone clue me in on the operation of the tx-in and tx-out jacks on
> the back of the Omni VI+? I hope to use the radio with a modified
> ALS-600 amp that has the QSK mod board installed and wonder what kind of
> interface will be needed from the out/in jacks to keep the radio safe.
> Any suggestions would be appreciated.
Quick theory of operation: TX OUT is a signal to the amplifier that
the Omni would like to transmit. The amplifier should key up in
response to that signal, and then send a return signal via TX EN that
the amp is ready to receive a transmission signal from the Omni. The
Omni then (and only then) keys up.
The signals are ground-true logic circuits. The Omni pulls the TX OUT
line to ground when it wants to transmit, and the amp pulls the TX EN
line to ground when it is ready to receive RF from the Omni. These are
jumpered when an amp is not installed so that the TX OUT plug pulls
the TX EN line to ground directly.
I just looked at the QSK-5PC, which is Ameritron's QSK mod board for
several of its amps, and note that it does not recommend installation
in an ALS-600. You use the "12V" jack on the QSK-5 with the "optional
instructions" to the collector output of Q6. That will pull that line
low when the amp is keyed up, and near as I can tell can be used for
the TX EN signal on the Omni. All this is from the manual for the
QSK-5 (I don't own one). Again, this may not be the QSK mod on your
amp, since it is not recommended for the ALS-600 and I'm not sure even
provides a means of being installed there. If that's the case, then
you'll have to figure out what the signals on whatever modification
was done on your amp actually mean (and how they are labeled).
Rick, KR9D
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