Is this with antenna or dummy load? Sent from my iPhone ...nr4c. bill
> On Jan 26, 2017, at 12:01 PM, Bill Leonard N0CU <billincol...@gmail.com> > wrote: > > I am having a strange problem with my K3s/10: the max output power on 20M > drops from 11.5W to 7.5W as the freq is moved from 14.0 MHz to 14.35 MHz. > All of the other bands stay above 11W across their respective bands. The > other interesting characteristic is that if I lower the power to 5W, there > is no drop- it stays at 5W across the entire 20M band. > > Other relevant data: > > -All data is taken post Cal > > -The drop on the 12V line when I key up the transmitter (set for 12W) is the > same at both ends of the 20M band: 13.9 to 13.4V as measured by the K3s. > > -Output power is measured with an LP-100A and is the same as shown on the > K3s. > > -The 20M BPF & LPF are flat to a few tenths of a dB and the SWR<2:1 across > the band. > > -The voltages and waveforms on the drains of the two FETs are identical, and > look OK to me. > > -The bias on both FET gates is ~2.6VDC. > > -The RF input signal to the KLPA3A (as measured at the XVTR output) is the > correct level and remains constant on all bands as the freq is moved across > the band. All spurious are down >50 dB. I also verified that the signal > level remains constant over the 20M band when the output power is dropping. > This suggests that the problem is not with the AGC or with any components > ahead of the KLPA3A. > > Since the problem does not occur at reduced (5W) power, it appears to be due > to some non-linearity. The FETs would be a logical candidate if it were not > for the fact that the problem only occurs on one band. I checked the temps > on all of the 20M LPF toroids and didn't observe any rise. > > I have no idea where else to look for a band specific non-linearity and have > run out of ideas on what else to check. Any suggestions would be greatly > appreciated. > > Bill N0CU > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/Strange-problem-with-K3s-10-could-use-some-suggestions-tp7626121.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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 n...@widomaker.com ______________________________________________________________ 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
