I can make you a very long list of amps and their finals which are destroyed by key down at full ham power for 10 minutes. I can make a long list of transceivers that will not run their rated power CCS. A K3 will do that by common experience, but Wayne ain't guaranteeing it. Typically we don't really expect ham transceivers to run CCS. Why would we expect ham amps to run CCS.
If you need CCS duty cycles at a particular power level, you can buy CCS military equipment rated for that power. OR, you can buy a ham amp that specifies a "brick on key" rating (usually a derating). Alpha's have them, and some others. The manufacturer needs to specify if there is a derating to CCS. A derating is not always possible (or admitted to) because the lower powers operate quite less efficiently, particularly in broadband transistor amps without variable tuning. Then there is this issue of running amps into awful antennas with marginal matching. Only the amp designer knows for sure if there is a CCS figure, and the mfr has to decide to take the risk and publish the figure. Many different manufacturers' ham amp models have been destroyed just by operating in contests at the manufacturer's published power level. You hear all about smoking amps at meetings of PVRC, YCCC, NCCC and the like. Contests are a continuing 40% duty cycle overall, digital contests maybe 50%, 55%. It appears that the KPA500 is designed for a 67% duty cycle, with a maximum key down of 10 minutes at full power. That's pretty darn good for an amp in a K3 box complete with power supply. Can wait and see if Wayne wants to stick his head out there and list a CCS power rating for it. You want to send 25 minute digital transmissions? Pay the money and get an Alpha. 1500 watts out CCS for their newer models. My old Alpha 76PA will do 700 watts out "brick on key", 1500 watts ICAS. The trick in the 76PA, is that you reduce the plate voltage for that (the old CW setting) and the 700 watts out is still in the sweet spot of the PI network design, so the tubes are efficient. 73, Guy. On Tue, Mar 15, 2011 at 6:16 PM, Tim Tucker <ae...@worldwidedx.com> wrote: > I'm a licensed Navy MARS operator. It is not uncommon to have very long > digital messages that need to be sent using digital modes that will take > longer than 10 minutes to send. This limitation pretty much eliminates > this > amplifier from being able to be used in my shack for MARS purposes. Now > with that said, we don't often need to use an amplifier to send digitally, > but in the event I did, I couldn't do it with this amp if there is a 10 > minute duty cycle. > > Tim > AE6LX > > On Tue, Mar 15, 2011 at 2:56 PM, Gary Gregory <garyvk...@gmail.com> wrote: > > > *Why? > > > > I cannot think of a way I operate that would exceed a 10 minute > > transmission. > > > > Other than a 'Fault' ? > > > > Gary > > * > > On 16 March 2011 07:50, S Sacco <nn4x.st...@gmail.com> wrote: > > > > > I'm not loving this part too much "Duty Cycle at 500 Watts 10 minutes > > > key down / 5 minutes off' > > > ______________________________________________________________ > > > Elecraft mailing list > > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > > Help: http://mailman.qth.net/mmfaq.htm > > > Post: mailto:Elecraft@mailman.qth.net > > > > > > This list hosted by: http://www.qsl.net > > > Please help support this email list: http://www.qsl.net/donate.html > > > > > > > > > > > -- > > > > *VK4FD - Motorhome Mobile > > Elecraft Equipment > > K3 #679, KPA-500 #018 > > Living the dream!!!* > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
