On the fairly rare occasions I go QRO with the KPA500 it runs off of a 120V wall outlet >50 feet from the breaker panel.
With the taps set so the key-up HV is near max (85V), the HV drops to close to the minimum voltage (60V) at 500 watts on some bands. That's all due to the 120V feed droop. There's no benefit from having the tap set for a mid-range voltage if the HV droops below 60V on key down. Below 60V the amp won't make full output on some bands and IMD is compromised. A self-protective circuit will kick in and shut the power supply off if the key-up voltage is too high. In that case you will get an immediate fault indication when you press the ON switch to apply power. It is useful to not have other heavy loads on the same circuit - especially loads that switch on and off (Microwave oven, household vacuum cleaner, etc.) Even if such loads do not cause the circuit breaker to open, they can cause the voltage at your outlet to shift even further. 73, Ron AC7AC -----Original Message----- > > On Feb 15, 2016, at 11:11 PM, Mike Crownover <a...@gvtc.com> wrote: > > > > I just bought a lightly used KPA500. It arrived from the seller, > > well packed and complete with cables, manuals, etc. I turned the amp > > on, interfaced it with my K3, keyed the radio and the KPA500 > > immediately shut-off. No fault light or error code, nothing. It > > shuts down just as if I had pressed the power button, the fan runs, > > etc... The antenna is resonant 1:1, I've lowered input power to 10 > > watts, swapped coax, hooked it up to another K3, used RCA to RCA > > cable, the Elecraft cable, etc.. When down to 10 watts input, I can > > tap the paddle like a straight key lightly and the amp works, but > > put two dits together and it > shuts down. > > > > > > > > Has anyone had an experienced anything like this. I keep thinking > > this has to be something simple. > > > > > > > > Mike AD5A ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
