Begin forwarded message:

From: Fred Castello fredcastello@gmail.com Subject: Fwd: Sequencers Date: March 20, 2017 at 5:09:28 PM EDT To: amsat-bb-request@amsat.org

Hello Folks,

I am trying to "bulletproof" my setup. My setup is a Kenwood TS-790A, preamps at the antennas for both 2 meters and 70 cms. powered through a separate control line (not via coax) and some M2 antennas (pictures and more details at my QRZ page: HERE https://www.qrz.com/db/KF4FC). I have a sequencer with up to 5 control points available. It seems that our implementation for sequencers is a bit different that most applications in that we have the possibility of needing to:

A) Transmit on 2 meters while listening on 70cms- i.e. 70 cm preamp on, 2 meter preamp off B) Transmit on 70 cms while listening on 2 meters. i.e. 2 meter preamp on, 70 cm preamp off

and this can change rather rapidly if multiple opportunities for passes are close. The way I am operating now is that I selectively turn on the preamp that I need for each pass and turn the other off. This is working, but even though I have rf sensing preamps, I do not want to chance transmitting SSB into either preamp. I am only transmitting 30 watts maximum and usually significantly less.

The Kenwood TS-790A has an “External Connector” on the back where I can access the PTT as well as having pins that can tell me when either 2 meters or 70 cms are being transmitted. All this said, it seems that I am in a bit of catch 22 because even though I can separate the PTT and for instance use a foot pedal to trigger the sequencer, the pins on the back of the rig will only change their signal AFTER the transmission has already started, so this signal is not helpful to determine which preamp to turn off and which to turn on. I realize that I could have a manual switch to go back and forth between using 2 meters and 70cms but that is essentially what I have now.

I am sure that I am missing something that somebody out there will suggest is very obvious. Help me understand how to implement a sequencer when we have two frequencies that can be in use at one moment in time and easily switch the next pass in an effort to make the station bulletproof so that I don’t blow up preamps.

Much Appreciated, Fred - KF4FC