Dear Folks:
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I have finished building the 50 watt amplifier kit for the QCX.? I am trying to run the test on page 66 of the manual which simply requires you to do the following:
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1)? Make sure that the R5 potentiometer is fully counterclockwise.?
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2)? Put the QCX in "Practice" mode so no RF is generated, but the radio will generate a voltage to key the amplifier.
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3)? After keying the amp via the QCX, measure the current draw between the amp and its power supply.
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4)? Once you have keyed the amplifier via the QCX and measured the amp's current draw, R5 is gradually adjusted clockwise until the current draw begins to rise.? Once you see the current draw rise, you turn R5 back to the level just below the point at which the current draw rises.? That is the correct setting for R5.
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I have done all of these procedures.? I should mention that the green "on" light comes on when power is supplied to the amp and that the red TX light comes on when I key the QCX.? The current draw measurement is 74 MA.? Unfortunately, the current draw never changes even when I turn R5 fully clockwise.
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I should mention that I did try the same measurement with the QCX practice mode turned off, i.e., the QCX would now be generating RF.? At that point I found that turning R5 gradually changed the current draw from about 97 MA to about 103 MA.? However, no RF is generated (though the QCX generates about 4 watts when it runs barefoot).? This makes me think that R5 is functional.
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Does anyone have any suggestions for locating the problem?
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Thanks and 73 de Bernie, KF0QS
