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#71: Proper PSK31 Audio Level setup with a scope, RF power meter, and ALC indicatorW2AEW |  |
| | | | SP6MLK | 16.11.2023 07:52:16 | 
Grupa: Administrator 
Lokalizacja:: Kłodzko JO80IK
Posty: 39657 #8130681
Od: 2013-10-18
| #71: Proper PSK31 Audio Level setup with a scope, RF power meter, and ALC indicator
This video shows how to properly adjust the audio drive levels from the computer sound card into your transmitter to avoid overdriving and creating a "dirty" PSK31 signal. It shows one example of what the distortion looks like on the RF envelope. Note that other rigs may distort "differently" than the one shown here. However, when adjusted properly, the RF envelope of all rigs should look similar to the "good" waveform shown here. The video shows that by adjusting the audio drive level to the point where there is barely any ALC action, or even none at all, will result in a clean PSK31 output. Personally, I like to adjust the audio level down just past the point where the ALC shows any activity, then go a little lower until the RF output power just begins to drop. This ensures that the transmitter is not doing any limiting or control of the RF output power, and will give a very clean result. You may choose to simply use the audio drive level as the main power control to drop the output from 100W to 10-20W for PSK31 (without touching the RF Power control on the rig). This will give a nice clean output also. Note that the RF power amplifier in most modern rigs is only rated for continuous operation at about 1/4 the full PEP rated power. Since PSK31 is near 100% duty cycle, it would be a good idea to keep the power well below 25W on a 100W rig. I typically run about 10W with great success. The video also discusses the scope setup a little, as well as a nice easy way to couple the RF signal into the scope using an unused antenna port on a tuner (making absolutely sure NOT to transmit directly into the scope. Here is some information on the interface between the radio and the computer:
TYLKO ZAREJESTROWANI I ZALOGOWANI UŻYTKOWNICY WIDZĄ LINKI » DARMOWA REJESTRACJA
TYLKO ZAREJESTROWANI I ZALOGOWANI UŻYTKOWNICY WIDZĄ LINKI » DARMOWA REJESTRACJA
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73! Stanisław Kłodzko JO80IK
IC-7300 + IC-9700 + (2m - 9el + 250W),
(70cm - 21 el + 250W), (23cm - 55 el + 150W)
| | | | | Electra | 02.05.2024 06:47:25 | 
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