Aire, Yes, that spurious signal on 28.004.5 is real and generated within the KAT500. Recent KAT500 beta firmware optionally shuts off an oscillator inside the KAT500 to suppress the spur. The oscillator is automatically turned back on by a number of events, such as pressing a button or transmitting.
The oscillator is also turned on by activity on the KAT500 serial port, which means that software like mine that polls the KAT500 to keep track of antenna port selection also keeps that spur alive. Sigh. Bill, K1GQ On 2013.06.29, at 07:02, Arie Kleingeld PA3A <p...@xs4all.nl> wrote: > Hi all, > > KAT500 + KPA500 connected to K3 through coax and elecraft interfacecables. NO > antenna connected to KAT500 (all 3 connectors open) > KAT500 and K3 connected to same DC-supply. > > KPA500 off (AC cord disconnected) > > Results: > KAT500 switched on, Mode = auto, ANT = 1, no antenna connected: *S4 birdie on > 28004.5 kHz* measured by K3 > > test 1: > - Changing ANT connector on K3: birdie gone. > - Change antennaconnected on K3 back: birdie S4 again > - Change to other antennaconnectors on KAT500 makes very little difference: > <0.3dB Measured on dBV meter of K3 with AGC off > - Disconnecting the elecraft interface cables makes NO difference. Keep them > disconnected for further tests. > > test 2: > - Switch off KAT500 (hold mode switch): birdie drops <0.5dB > - Disconnect DC from KAT500: birdie is gone. (proof that is has to do with > the KAT500) > > test 3: > - KAT500 switched on again > - Connect dummyload on ANT 1 of KAT500 with KAT500 on: birdielevel goes UP > +2dB (as compared to no dummyload connected in tests 1 and 2). S-meter now > now has gone up to S5. > - then switch off KAT500: birdielevel drops DOWN -10.5dB > - switch off KAT500: birdie gone > > Can anyone reproduce this? > > I have not checked all other frequencies, so this might be the only one. > Still this is a birdie that I cannot ignore. > > 73 > Arie PA3A > > > > > ______________________________________________________________ > 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
