[TenTec] Simultaneous Keying Question

[James Duffer]

Suggest you contact the ARRL, they haven been doing what you are attempting 
to do for years.....maybe you don't have to reinvent the wheel.  Hopefully 
you will find a simple, cheap solution.

73, Jim, wd4air


>From: "George, W5YR" <w5yr@att.net>
>To: wg6h@pacbell.net
>CC: Jim Reid <jimr.reid@verizon.net>, tentec@contesting.com
>Subject: Re: [TenTec] Simultaneous Keying Question
>Date: Sun, 02 Sep 2001 14:52:34 -0500
>
>Jim, from what you have told us, I cannot see any reason for having all
>three signals in time phase, i.e., simultaneously keyed.
>
>so, why not think about sequential keying? Key Rig A. At the conclusion of
>that code character, key Rig B. At the conclusion of its code character,
>key Rig C. And so on.
>
>That time diversity should greatly minimize the possibility of
>cross-products, etc. and the other problems that you have noted since only
>one transmitter is actually emitting at a time. Also, it seems to me that
>time diversity in keying would be far simpler to implement than space
>diversity in your antenna system.
>
>Perhaps I am missing a point in your system here, but seems like sequential
>keying would be much more appropriate even though it will require the
>development of the necessary keying logic.
>
>72/73, George W5YR - the Yellow Rose of Texas QRP-L 1373 NETXQRP 6
>Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
>Amateur Radio W5YR, in the 56th year and it just keeps getting better!
>Icom IC-756PRO #02121  Kachina #91900556  IC-765 #02437
>
>
>Bill Miner wrote:
> >
> > Jim,
> >
> > I have been watching your posts regarding this project and I do have one
> > caution for you!  If you do not have enough isolation between
> > transmitting antennas it is possible to get external RF back into the PA
> > of any of your transmitters and that PA will act as a high level mixer.
> > One symptom of this could be an increase in SWR.  At VHF/UHF and
> > microwave frequencies the fix for this is the use a circulator or
> > directional coupler on the output of the transmitter.  In your case I
> > believe the easiest method would be to make sure you have plenty of
> > distance between transmit antennas. This would mean
> > no antennas on the SAME boom! The most common of the mixing products is
> > 2A+B or 2A-B. As I am sure you will see.... some products will be
> > outside of the ham bands and may get you into possible trouble  with
> > some government agency!
> >
> > I believe a good source for additional information on this subject would
> > be someone at W1AW since they have lots of experience with multi
> > transmitters. Talking to W1RFI might be a good place to start.
> >
> > I hope this is helpful and I hope you are successful with your project.
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