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Author Topic: All about ALC  (Read 360 times)
DY1UBY
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Posts: 11




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« on: January 10, 2008, 10:05:10 AM »

I recently furnished my station with old Yaesu Musen FT-707 HF transceiver and starting to explore the HF bands. I have only a very elementary question and I think for those experienced hams they can help me out. my question is : What is ALC or Automatic Level Control? How it works? Please help. I apologize for my ignorance.
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WW5AA
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Posts: 2088




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« Reply #1 on: January 10, 2008, 01:40:02 PM »

No problem:

http://www.eham.net/articles/10183

73, de Lindy
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AA4PB
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Posts: 12788




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« Reply #2 on: January 11, 2008, 05:45:58 AM »

Basically when the amplifier is about to be overdriven it develops an ALC voltage that is fed back to the transmitter, causing it to reduce its output thereby preventing the amplifier from being overdriven.

In order to work smoothly the ALC system in the amp and the transmitter must match. There are no documented standards. The biggest issue is that the amplifier ALC output voltage level must be appropriate for the transmitter. Some amps have an ALC level adjustment. I've also seen problems with attack and decay times and load impedances that can affect the decay times.

You can run without ALC but you have to be very careful to control your transmitter output so that you don't overdrive the amplifier on peaks. In my opinion it is best to use the ALC and adjust your transmitter output to give the proper indication on its ALC meter. Then you know you are not overdriving.
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