A weak signal mode does not imply a low power mode. Bob, K4TAX
Sent from my iPhone > On Apr 4, 2020, at 11:15 PM, brianchapnick <[email protected]> wrote: > > > This discussion fascinates me only in that I wonder why you are using so much > power for weak signal modes? 5 or 10 watts should be plenty even with a > compromised antenna and poor band conditions......or am I missing somthing. > > Brian VE3GMZ > > > > > > Sent from my Samsung Galaxy smartphone. > > > -------- Original message -------- > From: Bob McGraw K4TAX <[email protected]> > Date: 2020-04-04 8:19 p.m. (GMT-05:00) > To: [email protected] > Subject: Re: [Elecraft] Max power for JT9 with K3S 100? > > Frank et al; > > > Just quoted what is in the K3S manual. No interpretation provided. I > agree that 100 watts key down is a lot for a SSB amplifier running in CW > mode. To me that says 100 watts for 10 minutes and then RX for 10 > minutes. Otherwise equal TX and RX times. Who does that? > > And if one is running "100 watts" then running CW or SSB for 10 minutes > might be the limit. Just speculation. On AM I might talk for 10 > minutes but that is at 25% rated power output for carrier, yet it is 100 > watts PEP. The 60 C is MY guideline. The KPA3A will shut down about 85 > C or so. > > On 6M I run my KPA500 at about 300 to 400 watts. The K3S is running > about 25 to 30 watts on 6M. At this point I'm watching the KPA500 > temperature. > > There is NO DX worth blowing a PA either in the K3S or the KPA500. > But I know guys that will blow things up, pushing things to the max and > beyond trying to work that DX station. I say bah humbug to that! > > I just pay attention to the PA temp, specially when running digital > modes. Likewise for the KPA500. > > 73 > > Bob, K4TAX > > > On 4/4/2020 3:41 PM, Frank O'Donnell wrote: > > Thanks for the replies. > > > > I've enabled the PA temp display (currently showing 22C right after > > power-up but before transmitting), and will keep an eye on that. > > > > Bob, I noticed that line in the K3S manual about the CW/SSB duty > > cycle. Does "100% - 10 min, 100 W key-down" mean that if you key down > > without stop in CW mode it can go 10 minutes at 100 watts? That seems > > like an awful lot. > > > > Where do the recommended TPO's for 6 meters, the 50% value for JT9, > > and the 60C guideline for the PA temp come from? > > > > Thanks again, > > > > Frank K6FOD > > > > > > On 4/4/20 6:22 AM, John Simmons wrote: > >> Fred Cady's book: > >> > >> "There are four fans speeds that turn on at different temperatures." > >> "If the temperature reaches 84 degrees C the KPA3 will be bypassed > >> until the temperature falls to stop any damage as a last-ditch backup > >> measure to protect your expensive power transistors from the excess > >> heat." > >> > >> -de John NI0K > >> > >> > >> Bob McGraw K4TAX wrote on 4/3/2020 6:39 PM: > >>> Frank: > >>> > >>> The duty cycle for the transmitter, as stated in the manual, is; CW > >>> and SSB modes, 100% - 10 min, 100 W key-down at 25C ambient. Do > >>> note that 6M has reduce power values of 85 watts {51 -52 MHz} or 70 > >>> watts {52 - 54 MHz} > >>> > >>> The duty cycle for JT-9, 1 minute transmit, 1 minute receive would > >>> be 50%. I frequently run 100 watts on WSJT-X FT-8 with no issues. > >>> Just pay attention to PA temperature. It should be 60 C or less. > >>> Also this is with FANS in the automatic mode. > >>> > >>> 73 > >>> > >>> Bob, K4TAX > >>> > >>> > >>> On 4/3/2020 4:18 PM, Frank O'Donnell wrote: > >>>> I've been using JT9 mode on 630m this winter with my K3S outputting > >>>> to an external class D amp. > >>>> > >>>> Now I'm interested in trying some JT9 QSOs with some people > >>>> currently operating on 160m. For me this would mean outputting > >>>> directly from the K3S (with internal tuner) to the antenna. > >>>> > >>>> Given the 1-minute cycle time for JT9, are there recommendations > >>>> (official from Elecraft, or otherwise) on maximum power to use in a > >>>> situation like this? And/or, is the answer dependent on the SWR I > >>>> can achieve with the antenna? > >>>> > >>>> Thanks and 73, > >>>> > >>>> Frank K6FOD > > > > ______________________________________________________________ > > 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]
