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Low or variable power for 2 pill amp help!!

newoldguy

Active Member
May 31, 2019
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hey everyone i have a small amp it keys 80 and swings to 125 with 2 watts in i would like to add a low power or variable power to it i really hate driving amps so hard it is a kicker 125 with 2 motorola 454's in it nice clean little amp i know it can be done but i really never done much with amps but i am wanting to learn here are a few pics and thanks for any help or direction. 202

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Since it was designed as on or off it should work fine. If anything I would lower the dead key input so the amp keys maybe 25-35 watts. That's what will overdrive it, too much dead key input. What's your peak input wattage?
 
Since it was designed as on or off it should work fine. If anything I would lower the dead key input so the amp keys maybe 25-35 watts. That's what will overdrive it, too much dead key input. What's your peak input wattage?
i key 2 watts swinging to 15
 
hey everyone i have a small amp it keys 80 and swings to 125 with 2 watts in i would like to add a low power or variable power to it i really hate driving amps so hard it is a kicker 125 with 2 motorola 454's in it nice clean little amp i know it can be done but i really never done much with amps but i am wanting to learn here are a few pics and thanks for any help or direction. 202

View attachment 33537
If you want to drop the output a bit you can squirrel in a 50 ohm Pi Pad attenuator using three resistors on the input side of the input matching network. Make sure you add it after the input relay so it only comes into play when transmitting. The basic idea here is to simply reduce the gain overall of the 2 pill amp. Always do that with attenuation on its input side since that yields the most linear behavior of the amp. You can initially experiment with the pad value by placing a 50 ohm switchable step attenuator ahead of the entire 2 pill amp to quickly figure out what amount of attenuation you want. Of course that temporary experiment will add loss to the front end noise figure of your transceiver. But once you know what attenuation you need then use an on line Pi pad calculator to determine the needed three resistor values and then place that pad in the 2 pill amp as I described. The alternative to this whole mess is to use a Galaxy or other rig with an RF Power Output control that you've tweaked for a really low minimum power such as 1/2 Watt.
 
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