[amsat-bb] Re: Linear sat half-duplex operating tips?

Greg D. ko6th_greg at hotmail.com
Mon Apr 20 20:03:08 PDT 2009

Hi Bill,

One other thing is to focus on the beginning and end of the passes, versus the center.  The rate of change in the Doppler shift is the worst right at the middle of the pass (time of closest approach).  Similarly, low elevation passes have less shift change than higher ones, and higher orbit satellites (e.g. AO-07) have less shift change than low orbit ones (e.g. VO-52).

Another thought is to use your own RIT to compensate for the other station's change, especially on the birds with 2m uplinks.  That way you can hear him clearly without changing your own uplink.

Announcing you're running HDX will help if the operator on the other end is experienced.  An inexperienced operator probably has enough to worry about, without trying to understand what to do with this new challenge.  I worked an HDX operator a long time ago on RS-12/13, I think, and was puzzled why he was so difficult to work.  Then I got his QSL card, listing the equipment, and understood.  It was odd enough that I remember the contact to this day.  

Best wishes (that you find a second rig...),

Greg  KO6TH

> Date: Sun, 19 Apr 2009 07:13:10 -0700
> From: billdz.geo at yahoo.com
> CC: amsat-bb at amsat.org
> Subject: [amsat-bb]  Linear sat half-duplex operating tips?
> I have been operating the linear sats over the past week on half-duplex, using a single IC-7000 controlled by SatPC32.  I've made several contacts, but it has been quite difficult.  Obviously the best remedy is to get a second rig and run full duplex, but in the meantime, does anyone have any tips for successful half-duplex operation?
> One tip I received from NJ1H is to announce at the start that I am running half duplex, since most stations manually adjust the uplink so that the
> downlink stays constant. If the other station knows I am running half-duplex, he should adjust the downlink instead of the uplink.
> Any other suggestions?
> 73, Bill NZ5N
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