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Re: [TenTec] Digital (PSK31) Communications

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] Digital (PSK31) Communications
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 3 Feb 2008 13:37:22 -0600
List-post: <mailto:tentec@contesting.com>
Correction -  we must NOT light the ALC LED with PSK-31 signal.

As to reducing output power, either reduce mic gain or reduce sound card 
output.

73
Bob, K4TAX



----- Original Message ----- 
From: "F8EHJ" <f8ehj@free.fr>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, February 02, 2008 1:26 PM
Subject: Re: [TenTec] Digital (PSK31) Communications


OK, thanks,
We must light ALC LED and what about MIC GAIN ?

If I want reduce OUTPUT RF POWER, do I must reduce MIC GAIN ?

73's
herve F8EHJ



Le 2 févr. 08 à 18:41, Bob McGraw - K4TAX a écrit :

> Agreed.  If the ALC light blinks either you have too much mic gain
> or too
> much signal from the sound card.  There should be NO ALC action for
> a good
> clean PSK-31 signal.
>
> With Tentec radios, when properly adjusted and with the correct
> level from
> the sound card, you should receive IMD reports during idle from the
> other
> station in the order of -25 to -30 dB.  If your IMD is higher than
> this,
> i.e. -20 to - 10 dB, then you have too much signal from the sound
> card or
> you are operating the transmitter at too high of power output.
>
> If you are not sure, ask a station that you are in contact with to
> give you
> an IMD report. To do this you must not transmit data, just let the
> system
> idle without typing for 10 to 20 secs.  Have the other station let the
> software on the receiving end provide you a signal report.  If your
> IMD is
> high, then reduce the level from the soundcard or the interface
> device that
> you are using.
>
> For a 100 watt radio, your power output should be 25 to 35 watts.
> It all
> cases it is normal to have the radio set so that it is capable of
> producing
> 100 watts of output.  However, it should be driven with level from
> the sound
> card so as to produce no more than 25 to 35 watts of actual power.
> Do not
> turn radio power down.  Turn sound card level down.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "KXB" <w7kxb@msn.com>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Saturday, February 02, 2008 11:28 AM
> Subject: Re: [TenTec] Digital (PSK31) Communications
>
>
> Hello Herve
> In psk, "DO NOT BLINK THE LIGHT" period
> Carry-on
> Bill Harris w7kxb
>   ----- Original Message -----
>   From: F8EHJ<mailto:f8ehj@free.fr>
>   To: Discussion of Ten-Tec Equipment<mailto:tentec@contesting.com>
>   Sent: Saturday, February 02, 2008 8:49 AM
>   Subject: Re: [TenTec] Digital (PSK31) Communications
>
>
>   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<mailto:roncasa@verizon.net>>
>> To: "Discussion of Ten-Tec Equipment"
> <tentec@contesting.com<mailto: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"
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>>>
>>
>>
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