[TenTec] O2 output level with PSK aux

jmiller1706 at cfl.rr.com jmiller1706 at cfl.rr.com
Wed Feb 11 15:17:39 EST 2009

What I saw as a "sine" envelope is apparently normal for PSK, and probably not some kind of ground problem.  See waveform descriptions at:
http://www.ssiserver.com/info/pskmeter/pacificon2002.pdf or http://www.rcarc.org/presentations/PSK31.pdf
But the fact that it does have a varying envelope could account for the lower average power readings.  

Waveform shaping is used to soften "key clicks" caused by sudden phase reversals.  "In PSK31, a cosine shape is used. To see what this does to the waveform and the spectrum, consider transmitting a sequence of continuous polarity-reversals at 31 baud. With cosine shaping, the envelope ends up looking like full-wave rectified 31Hz AC."  http://bipt106.bi.ehu.es/psk31theory.html

This is a learning process so I am hoping this is nothing more than an operator problem, most likely it is.  Thanks for the interest, but you may be hearing more.  ;-)

Jim N4BE

---- Ron Castro <ronc at sonic.net> wrote: 
> That is beginning to make more sense, although the sine modulation may 
> indicate there is a hum problem lurking somewhere!  If you can't push the O2 
> into ALC range, the output from the Navigator is too low.  Even if you don't 
> want to run ALC in normal operation, there should be enough input to drive 
> it there when everything is 'maxed out'.
>          Ron Castro
>  Chief Technical Officer
>     Results Radio, LLC
>                N6IE
>       www.N6IE.com
> ----- Original Message ----- 
> From: <jmiller1706 at cfl.rr.com>
> To: "Ron Castro" <ronc at sonic.net>; "Discussion of Ten-Tec Equipment" 
> <tentec at contesting.com>
> Sent: Wednesday, February 11, 2009 12:49 PM
> Subject: Re: [TenTec] O2 output level with PSK aux
> > Thanks to all for the suggestions.  On RTTY AFSK (basically a constant 
> > carrier)I do get about 80-90 watts out on second measurement, with 
> > Navigator set to max outputs.  The Navigator still seems to be a bit light 
> > on drive for an Orion however.  Now, looking at PSK on a scope, I see that 
> > it is not exactly constant amplitude when idling, as I had assumed 
> > erroneously previously - seems to have a slow sine modulation envelope on 
> > it.  I assume that's normal (?).   This could account for the lower 
> > average power reading on the wattmeter in that mode.  When I set the 
> > wattmeter to peak/hold, it shows close to 90 watts (by capturing the 
> > peak).  Of course that's too much, but I think that explains some of the 
> > discrepancies.
> > N4BE
> >
> > 
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