It's a 12 volt build.
I was getting 3-5 watts depending on the band.
QMX+ voltage display was a couple of 10ths less than the set supply voltage, which I have verified as being as accurate as my meter.
Testing was done with the QRP-LABS 20 watt dummy load.
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I read the document that Ludwig referred to.? When transmitting, the signals coming from IC503 are 180 degrees out of phase, but are not symmetrical.
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Currently, I have a strange symptom.? When I turn the radio on, it draws about 600 mA, and Q507 heats up.? The strange part is that the current drops to around 100 mA when I enter the diagnostic screen.? Upon further investigation, I find that the current output on my power supply shows 652 mA when transmitting, and 652 mA when I'm not sitting in the diagnostics screen.? I find that to be suspiciously coincidental.
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Once I get to the diagnostic screen, I see the transmitter voltage sitting at 0.4 V.? The wiki document Ludwig referred to indicated that to be problematic.? That voltage jumps to about 0.8 V when I attempt to transmit.? When I transmit, the 5 V SMPS duty cycle jumps to around 75%.
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I plan on replacing IC503 and even though 3 of the 4 finals tested good, I'm going to replace them as well.? However, I don't see how that's going to remedy the current draw problem when not in the diagnostic screen.
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Sure would like to understand the mechanism that causes the current to drop when I enter the diagnostics screen.? I don't think I fully understand what number 6 in the wiki doc is trying to say.? It indicates a non-zero transmitter voltage as undesirable, but doesn't really discuss where to look for the problem or how to fix it.
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Thanks.
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Andy
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