Re: 10W HF Linear Power Amplifier troubleshooting
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You won¡¯t see a current increase until you reach the gate threshold voltage. That could be something like half the pot range before you start seeing an increase in current. Turn it up slowly and when it starts to increase, slow down and carefully set it at the proper amount. Hope that helps.?
Ron
On Mon, Nov 26, 2018 at 20:38 Ken wa4mnt < wa4mnt@...> wrote: Gang,
Before I smoke something I'd like to get some advice on how to proceed. Today I received and assembled the 10W linear. All parts were included with no extras left over. I check each value before soldering and do one component at a time. All the wound inductor's continunity checked as described, semiconductors and diode orientation appears correct. I mounted as described on the heatsink, rotated both pots fully counterclockwise, and grounded the TX input. I then applied 12.5V and proceeded to the bias adjustment. At rest, I get 2.5mA current draw with no increase on either pot when adjustment is attempted. The only other check I made was to verify that there was 5V at the output of the 78L05. I attached a few pics of the assembled board, for what they are worth. Any help will be greatly appreciated.
ken - wa4mnt
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Ronald Taylor