Re: [TenTec] Digital (PSK31) Communications

[F8EHJ <f8ehj@free.fr>]

Hello,

I subscribe to this list for this reason :
What is the adjustement for PSK31 using a Ten tec jupiter.

I am agree with you that ALC indicator should not be always lighted.
So I adjust sound card output level to have ALC led blinking with  
modulation.
But what about MIC GAIN ? I selected in the menu line mic for input.

There is a relation between MIC GAIN, ALC and RF OUTPUT !

If I decrease RF POWER I must decrease MIC GAIN to have ALC blinking.  
(or I must decrease sound card OUTPUT LEVEL.
Thanks for explain.

best 73's

Herve F8EHJ

TENTEC JUPITER 538
MICROPHONE 706 DESK


Le 2 févr. 08 à 17:38, Bob McGraw - K4TAX a écrit :

> A comment to the point of setting vs. controlling the power on the  
> Jupiter.
> For modes like PSK-31 the Jupiter should be configured to operate  
> at its
> rated output power or 100 watts.  Then the actual power output  
> should be
> controlled by the PSK-31 software or the sound card output level or
> interface output level to the Jupiter so as to cause the Jupiter to  
> produce
> some 25 to 35 watts of power.  This will prevent the ALC activation  
> and
> subsequent distortion from being generated and transmitted.  Also,  
> any SP or
> speech processing should be OFF.
>
> It should be noted that the PSK-31 signal will cause the power  
> output to
> vary slightly depending on if idle or data is being transmitted.   
> This is
> normal and the amount of variation depends on several factors, such  
> as tone
> frequency, power meter response and dampening and etc.
>
> Here is the basic NO NO.  Reduction of the Jupiter power to 25 to  
> 35 watts
> and then have the sound card audio drive the Jupiter to 25 to 35  
> watts will
> activate the ALC and subsequent distortion of the transmitted  
> signal will
> likely result.  This produces a transmitted signal that is several  
> hundred
> Hz wide and thus an annoyance or interference to others on the band.
>
> In general it is frowned upon to run "high power" on PSK-31.  The  
> issue with
> this lies in the fact that an exceptionally strong signal adjacent  
> to a weak
> signal, both within the IF passband,  will cause the strong signal to
> capture the AGC and thus further suppress the weaker signal.  As a  
> general
> "rule of thumb" one should always operate with actual PSK-31 power  
> output
> being no more than 25% to 35% of the rated transmitter power.
>
> 73
> Bob, K4TAX
>
>
>
>
> ----- Original Message -----
> From: "ron" <roncasa@verizon.net>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Saturday, February 02, 2008 9:42 AM
> Subject: Re: [TenTec] Digital (PSK31) Communications
>
>
> > Henry Mackey wrote:
> > >   The power setting on the Jupiter was at 100%. However, I would  
> > > reduce
> > > the power according to the rigs meter to 20-25 watts and avoid  
> > > any ALC.
> >
> > 25 watts??
> >
> > For a mode that only needs minimal wattage??
> > Try less and be amazed. (the spectrum would also be cleaner if we  
> > all did)
> > (smile)
> >
> > Ron
> > "the 516 is a keeper"
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
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