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Werner,?
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the situation you describe - low power , a bout half expected output? seems to arise , historically where people have one side of the class C pair??working but for component failure reason or bad soldering reason the other side of the push push circuit is?not working.? NB your supply would need to be good for around sixty W if you want this unit to supply 25 W out? - read on
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1. CHeck that you do have the bias voltage available when the PTT is triggered. By which a Mean a full five?
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volts out off the regulator.? Perhaps the regulator has failed or is at some lower voltage.? Generally if you?
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put in a five volt regulator 78LM type backwards it simply does not function.??
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2? Trace that voltage across to the? R5 potentiometer.? Check that this is really a five K unit. If it is 10K?
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or something like that then the return signal in the? gate path is throttled.? ?check it is physically?
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assembled correctly and the slider is bearing well.
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3.? check that the bias (once the PTT is asserted) is getting all the way to the respective MOSFET gates.? Bad?
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stripping of the? wire in the trifilar transformer could be the issue - it might look like a good solder joint?
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but one of the gate joints might be defective.
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4. At this point if the phasing TFR? is built and stripped correctly with the correct phasing then you have to?
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start suspecting the MOSFETs.
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5 if you put a? leaded one ohm resistor in the Drain leg of each mosfet as? a temporary connection you can see?
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they are responding properly in static mode to increases in common gate? bias. Clearly you have to measure the?
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voltage under the respective resistor to GND and watch it for both Mosfets.
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6. Did you put in the RF? OPut transformer with the three turn secondary pointing in the correct direction ?.?
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I am guessing this might be a common fault for those who do not follow directions precisely. :
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At nineteen volts supply and with 5 W RF in then you should have about 25 W out.? This is a class C device . If?
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feed it with say 2.5 W in you will get to next to nothing out, far less than a proportional calculation would??suggest.?
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TE Fidler
Timothy Fidler