The FCC document on estimating RF exposure lists “duty factor” for various modes. That is average power compared to peak while transmitting.
SSB 20% SSB with heavy speech processing 50% FM, FSK, RTTY, carrier 100% CW 40% Separately, they talk about on/off periods, the average time spent transmitting during a 6 minute or 30 minute period. See pages 14 and 15. https://transition.fcc.gov/bureaus/oet/info/documents/bulletins/oet65/oet65b.pdf wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On May 4, 2020, at 7:40 AM, Randy Moore <[email protected]> wrote: > > ICAS means Intermittent Commercial and Amateur Service. > > From the RCA Transmitting Tube Manual: > > Intermittent Commercial and Amateur Service (ICAS) covers aplications in > which high tube output is a more important consideration than long tube life. > The term "Intermittent Commercial" in this title applies to types of services > in which the operating or "on" periods do not exceed 5 minutes each, and are > followed by "off" or stand-by periods of the same or greater duration. The > term "Amateur Service" covers other applications where operation is of an > infrequent or highly intermittent nature, as well as the use of tubes in > "amateur" transmitters. ICAS ratings generally are considerably higher than > CCS ratings. Although the ability of a tube to produce greater output power > is usually accompanied by a reduction in tube life, the equipment designer > may decide that a small tube operated at its ICAS ratings meets his > requirements better than a larger tube operated within CCS ratings. > >> On May 4, 2020, at 8:55 AM, John Simmons <[email protected]> wrote: >> >> Nowadays manufacturers use 'ICAS'. One even specs their amp for '100% duty >> cycle ICAS'. ICAS=Intermittent Continuous Amateur Service'. Gobbledegook! >> >> 100% duty cycle is what Alpha used to say.... brick on the key forever. FT8, >> JT65 are 50% duty cycle modes. SSB is about 33% during transmit, CW is 50% >> during transmit. Duty cycle has no time limit. >> >> -de John NI0K >> >> Dave Cole wrote on 5/4/2020 8:39 AM: >>> Hi Rick, >>> >>> This brings up a point I have been unsure about for years... Duty Cycle... >>> What constitutes 100%? Over how long a time frame? >>> >>> If I run JT65, (one minute on one minute off), and I use a timeframe of say >>> 5 minutes, I buy it is 50% duty cycle. >>> >>> But if I use a timeframe of one minute it is 100% Duty Cycle... >>> >>> So when stating duty cycle it is important to spec the timeframe, as you >>> did... Is there an actual timeframe stated someplace as a standard? >>> >>> I do like the way you stated it by the way... With time to 'catch the >>> breath'... >>> >>> 73, and thanks, >>> Dave (NK7Z) >>> https://www.nk7z.net >>> ARRL Volunteer Examiner >>> ARRL Technical Specialist >>> ARRL Asst. Director, NW Division, Technical Resources >>> >>>> On 5/3/20 8:53 PM, Rick Bates, NK7I wrote: >>>> I didn't add the obvious, FT8 in that manner is a 50% duty cycle but with >>>> enough time to 'catch the breath'. >>>> >>>> I remember back when it first came out, Wayne suggested to 'run it with >>>> all the LEDs lit' or something along that line but... it's capable of MUCH >>>> more than 500 watts and wisely better limited by firmware upgrades (in the >>>> early days I watched it put out almost 700, at which point I was far more >>>> cautious). It's nice to know there is a certain amount of 'overhead'. >>>> >>>> Rick NK7I >>>> >>>> >>>> On 5/3/2020 8:23 PM, Dave Cole wrote: >>>>> Hi Rick, >>>>> That is how mine behaves as well, almost exactly like that... However, I >>>>> will be running SSTV, and that is hard on the amp... I need to do a bit >>>>> more testing prior to that. >>>>> >>>>> As someone else said upthread, half power is really tough on the amp... >>>>> >>>>> 73, and thanks, >>>>> Dave (NK7Z) >>>>> https://www.nk7z.net >>>>> ARRL Volunteer Examiner >>>>> ARRL Technical Specialist >>>>> ARRL Asst. Director, NW Division, Technical Resources >>>>> >>>>> On 5/3/20 7:52 PM, Rick Bates, NK7I wrote: >>>>>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking). >>>>>> >>>>>> At 530 watts output (on the display and utility) into a 1.13:1 antenna >>>>>> load (SteppIR) for a ten minute calling period (Mongolia then Oman), the >>>>>> temp rose to 66C; a few moments of elevated fan quickly brought that >>>>>> down to the low 60's between transmissions. >>>>>> >>>>>> Ambient room temp 77F. (Both calls succeeded.) >>>>>> >>>>>> Rick NK7I >>>>>> North Idaho >>>>>> >>>>>> On 5/3/2020 7:42 PM, Andy Durbin wrote: >>>>>>> "It is interesting to hear how others experience their KPA500s over >>>>>>> various conditions." >>>>>>> >>>>>>> I have over a years's worth of KPA500 data recorded but it takes some >>>>>>> effort to run it through the Excel templates to make pretty plots. >>>>>>> >>>>>>> My KPA500 temperatures are strongly influenced by ambient temperature. >>>>>>> Shack temperature is often over 30 deg C in the summer months and it's >>>>>>> not at all unusual for my fan to run at level 3 in FT8 QSO. I think I >>>>>>> have only reached fan speed 5 twice and that was while running >>>>>>> temperature tests not while operating. I terminated those tests at >>>>>>> fan speed 5 and didn't wish to push it any higher. >>>>>>> >>>>>>> So many people seem to think reducing the output power will keep the >>>>>>> temperature down. It does not. Half power is about the worst heat >>>>>>> dissipation condition for the KPA500. >>>>>>> >>>>>>> 73, >>>>>>> Andy, k3wyc >>>>>>> ______________________________________________________________ >>>>>>> Elecraft mailing list >>>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>>>>> Help: http://mailman.qth.net/mmfaq.htm >>>>>>> Post: mailto:[email protected] >>>>>>> >>>>>>> This list hosted by: http://www.qsl.net >>>>>>> Please help support this email list: http://www.qsl.net/donate.html >>>>>>> Message delivered to [email protected] >>>>>> ______________________________________________________________ >>>>>> Elecraft mailing list >>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>>>> Help: http://mailman.qth.net/mmfaq.htm >>>>>> Post: mailto:[email protected] >>>>>> >>>>>> This list hosted by: http://www.qsl.net >>>>>> Please help support this email list: http://www.qsl.net/donate.html >>>>>> Message delivered to [email protected] >>>>> ______________________________________________________________ >>>>> Elecraft mailing list >>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>>> Help: http://mailman.qth.net/mmfaq.htm >>>>> Post: mailto:[email protected] >>>>> >>>>> This list hosted by: http://www.qsl.net >>>>> Please help support this email list: http://www.qsl.net/donate.html >>>>> Message delivered to [email protected] >>>> ______________________________________________________________ >>>> Elecraft mailing list >>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>> Help: http://mailman.qth.net/mmfaq.htm >>>> Post: mailto:[email protected] >>>> >>>> This list hosted by: http://www.qsl.net >>>> Please help support this email list: http://www.qsl.net/donate.html >>>> Message delivered to [email protected] >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [email protected] >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
