Are the Flex 6000 series transmitters rated for 100% duty cycle operation?

Russ Ravella

After reading the published specs that I can find and searching the "Community" I can't find a solid, official, straight forward answer to this question.  I'd like to know if I can operate my new 6600 at full power (100W) in RTTY, FT8 etc. modes.  There are unofficial statements here and there but nothing concrete and official which makes me a bit nervous.

I'd like to avoid the inevitable "FT8 is a low power mode" and "what matters is splatter" debates, I'd just like to know what the current model transmitters are rated for.  Thanks!

mikeatthebeach .

My 6600M when set to 100 watts puts out 30 to 40 watts max when driven in DIGU mode for
FT8 and Audio is in Yellow Zone and not overdriven into the Red Audio Zone
In Green Zone the 6600M output is between 15 to 20 Watts output for me
73 Mike

Martin AA6E

No problem running FT8 or RTTY at 100W output on my 6500. If you run for a long time, the fans go to high speed and make a racket. Flex more or less says this is safe. The Tx will shut down if it really gets too hot. As to "official", ham gear usually has lots of parameters that aren't specified or fully guaranteed. Flex gear is advertised as 100W output, and that's what I get.


@mikeatthebeach: Check your audio and/or processor levels?

100 W should be possible with single tone modes like FT8, CW, RTTY, etc. (But don't try it for PSK31 or multi tone modes that need linearity.)


73 Martin AA6E

Bill -VA3WTB

Ft8 is a high power low signal mode.
Yes, the radio's are designed for 100% duty cycle.

Martin AA6E

We're all supposed to use only the power necessary to communicate. With FT8 or any other mode, that could be a mW or a kW depending on conditions. FWIW.

Russ Ravella

Got a great official answer to this from Tim today.  He's probably answered this question a thousand times before but I couldn't find it stated crisply like this.  Here's what he said:

"The problem is there is no clear definition of "full" duty cycle in the ham world.  In the broadcast world, yes.  We are rated at 100% ICAS (Intermittent Commercial and Amateur Service)  ICAS implies a limited operating or 'on' period followed by an 'off' or standby period of at least the same or longer duration.  From a pragmatic standpoint, You can run "full duty cycle" modes like FT8 or RTTY all day and have no issue.  The radio will get hot and the fans will spinn up to cool the PA transistors down, but the PA in the radio is derated, so there is a lot of headroom in this regard."

Tim Ellison, W4TME
Customer Experience Manager

Exactly what I was looking for - Thanks Tim!

John - AI4FR

Thanks for posting the follow-up!!