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They don't give you a way to break the power connection to the amplifier board and insert a current meter.

We adopted the practice of just putting a 20-Amp meter in line with the radio's positive power lead, keying it on sideband with the mike gain at zero, and setting the two bias trimpots for minimum reading. This would be zero bias on the amplifier transistors.

Each trimpot now gets advanced to show 100 mA increase in the reading. Idle current of 25 mA per transistor may sound low, but it improved reliability without reducing power very much.

Setting gate bias on MOSFETs with a voltmeter on the bias voltage is risky business.

The actual current draw of the transistors is what you should be measuring, even when they make it tough to do.

73

[QUOTE="nomadradio, post: 684441, member: 22"] They don't give you a way to break the power connection to the amplifier board and insert a current meter. We adopted the practice of just putting a 20-Amp meter in line with the radio's positive power lead, keying it on sideband with the mike gain at zero, and setting the two bias trimpots for minimum reading. This would be zero bias on the amplifier transistors. Each trimpot now gets advanced to show 100 mA increase in the reading. Idle current of 25 mA per transistor may sound low, but it improved reliability without reducing power very much. Setting gate bias on MOSFETs with a voltmeter on the bias voltage is risky business. The actual current draw of the transistors is what you should be measuring, even when they make it tough to do. 73 [/QUOTE]

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