Flex 6400M current draw vs my other rig.

Ross Slater

I have a 6400M and a Icom 7300 using same power supply, tuner and antenna. My question is why does the 6400M draw so much more current then the 7300? Example on 30m FT8 running 60 watts 1:1 SWR (with external tuner) the 6400m runs around 20-22 amps. When I switch over to the 7300 it's runs at 13 amps. Thanks.

Erik Carling EI4KF

My 6400M draws 23 amps at 100 watts. At 60 watts it draws only a little less, around 19 watts. I guess it is just more electronics versus the 7300, like the screen for example. The difference between my 19W and your 22W is probably only PSU meter calibration error.

Ross Slater

Thanks Erik

Stan VA7NF

You are making apples and oranges comparison. The flex uses a high current bias to place your signal in the linear portion of the amplifier operation. Your numbers are higher than in my 6700 case - 17-18A at 14V which is around 250W for both keeping the RX running while transmitting. In round figures half that power is final bias and half is your transmitted signal.

The 7300 is ICOM's low cost entry into the (as they call it) SDR world. I cannot speak to ICOM's cost engineering but am not surprised that the transmit final amp bias is set for a much lower power draw as less bias current requires lower power transistors and lower cost powering circuits; aka cost engineering. I expect flames.

Ross Slater

Thank you I understand now after doing a little more research and some input from other operators.