My Flex 6500 will only put out around 80 watts why?

David_K6FA

I can't seem to get any more than that amount of output power on CW. I have the same with FT8 but I am not worried about that as I work most of what I hear. I am keying the 6500 with an external key at this time.

What adjustments do I need to check to get the 100 watts out?

I will be running either N1MM or N3FJP for the upcoming CQWWDX CW contest and would really like the 100 watts.

Rich M5RIC

Check in the TX tab in radio set-up you have the max power set to 100. You can see here it's set to 20, if that's set to 80 for you it will mean you can only go to 80.

Obvious but check the RF slider is all the way up too.

Mike-VA3MW

With the radio under full 100 watt load, what is the voltage when measured on the back of the radio (or with FRStack)?

ka9ees

@David_K6FA I would look at the SWR of the antenna. The rig may be rolling back.

David_K6FA

Rich M5RIC:

Has been set 100 since I have had the radio. Slider all the way up.

David_K6FA

Mike VA34MW

I measure the voltage at the power supply since I am unable to get the voltage at the radio. At the supply in receiving the voltage is 13.85. When I key the radio in CW mode to my antenna the voltage at the supply is 13.71.

In the radio setup tab, the power has always been set at 100 watts. My power slider is set all the way up.

In DAX the TX streaming is set so I see the white tab in the Level, so it is below 0. That comes to around 48 on TX Gain. (FT8 & RTTY)

KD0RC

Hi David, you can get the voltage that the radio sees internally from SDRMonitor, FRStack, FlexInfo and probably some other utilities.

I set my Astron to supply 14.2 V as seen internally by the radio. This gets me the full 100 watts out from my 6400, and now my 8600.

Mike-VA3MW

It is critical to read it on the back of the radio. It is very common that there is a voltage drop involving the cable. The 100% RF output power is directly related to the DC voltage at the Power Amplifier.

It only takes 1 ohm of resistance in the cable to make a huge difference in output power.

Mike

Geoff AB6BT

Just to expand on Mike's comment…1Ω of resistance will drop 20 Volts at 20 Amps!

100mΩ will drop 2V at 20A.

10mΩ will drop 200 mV at 20A.

E=IR