Data: FR 6400 Power Draw

Pat_W5WTH

I leave my rig on 24x7 and was curious as to the power consumption. I took three quickie reading.

Setup was FLEX 6400 and PowerWerx SS-30DV. US Mains, 120VAC

~43W draw in Receive only.

~165W draw with Transmit power at 10W during CW keydown.

~400W draw with Transmit power at 100W during CW keydown.

Neil D Friedman N3DF

Why would a solid-state receiver draw 43 watts?

Pat_W5WTH

It's the measurement I got. Granted, I did not use a lab grade AC power analyzer to make the measurement.

The FR is basically a high end PC + some other 'stuff'. 43W seems ok to me. Plus, this includes the Powerwerks supply.

Neil D Friedman N3DF

The manual for my 6600M says it draws about 1.7 amps in receive.

Neil D Friedman N3DF

The manual for my 6600M says it draws about 1.7 amps in receive.

Lionel

My 6400 is using less than 2A in RX, as shown on my PS ammeter. I don't ever recall seeing it any higher in RX.

Neil D Friedman N3DF

The manual for my 6600M says it draws about 1.7 amps in receive.

Patrick

Assuming that the PS is an analog type. One has to work the power consumption backward to the mains. The stated consumption is for 13.8 V at 1.7 A, that works out to 23.46 W on the DC side. Analog PS’s are around 50% efficient, and thus working backwards is 2x23.46=46.92 W, minus losses, which brings it to an estimated 43 W as presented. So it is pretty close to specifications. If a switching PS would have been used, which are around 93% efficient. Then the losses would be around 7 percent giving us about 25 watts at the mains based on 1.7A at 13.8 volts.

Stan VA7NF

The draw in TX is in two parts, A) the bias applied to the final amplifier and B) Output power.

Flex seems to use a near class A amplifier with increasing bias for higher power, lacking more detailed data, the ROUGH calculations, as I have witnessed with a FR 6700 and using the previously reported power levels:

RX: 43W total - 27W FR in receive = 16W PS overhead at 2A draw (PS power servicing the 2A (27W) FR draw)

TX at 10W CW Key down: 165W total - 25W PS overhead at 10A - 25W FR electronics without final - 10W transmit CW = 110W bias

TX at 100W CW Key down: 400W total - 45W PS overhead - 25W FR electronics - 100W transmit CW = 230W bias

These numbers demonstrate the FR final bias is roughly double the peak power output with a 100W minimum. This biasing keeps the final from producing clipping harmonics and other output distortions especially for SSB signals (as a much older CW amplifier does while running in class C)

Be thankful the FR produces such a clean output at such a low final voltage.

Pat_W5WTH

@Stan VA7NF ... your measures seem to align with mine. Thanks!

KD0RC

Thanks for this Stan. I noticed that my Flex 6400 is pretty **** my RV batteries when doing a lot of transmitting (like during Field Day). This explains why! Well, I am glad to sacrifice some efficiency to gain signal purity. There are so many terrible, splattery signals out there and I am just glad to not be one of them!

KD0RC

Thanks for the explanation Stan, I really appreciate it! I was wondering why my Flex 6400 was so **** my RV batteries when I transmit a lot (like during Field Day), and now I know! Well, I would rather lose a little efficiency than put out a crummy, splattery (is that even a word??) signal. There are so many terrible signals from misadjusted equipment out there, I am just glad to not be one of them!