I have a K3 and a K3S at my Caribbean station... I see the same behavior on my K3S but not on the K3. I've calibrated it several times but have not diagnosed it past that. I've seen the power vary by as much as 50% at times.
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch K9ZC Staunton, Illinois Owner Operator Villa Grand Piton J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook! Moderator North American QRO Group at Groups.IO. email: [email protected] -----Original Message----- From: [email protected] <[email protected]> On Behalf Of Conrad PA5Y Sent: Wednesday, October 21, 2020 6:50 AM To: [email protected] Subject: [Elecraft] Amplitude variation on K3S with JT65B Hello while I wait for feedback from the (no doubt overwhelmed) Elecraft support I thought that I would ask the group about a problem that I have with my K3S. When I run JT65B and even to a lesser extent FT8 I see unacceptable amplitude variation on both the 6m output and the transverter output (on 28MHz). If I put my E4406 Spectrum analyser on peak hold with a narrow span and 10Hz RBW I see amplitude variations of a little over 1dB on the modulation tones across the passband. To save time. 1. On the ALC meter I have 4 bars lit up with the 5th occasionally flickering - the audio drive level is correct; it is not an ALC issue 2. I calibrated the TX drive - the effect is observed at 1mw, 5W, 50W and 100W on 6m. 3. I am using DATA A so no TX EQ or compression 4. The audio has from WSJT-X been measured on a UPV audio analyser and there is less than 0.1dB variation when using a UMC404HD sound card 5. The effect is observed with both Line input drive and the UMC404HD soundcard and the internal K3S codec 6. My old TS2000X does not exhibit more than 0.1dB amplitude variation with the same sound card providing audio and the same test setup 7. I have verified the amplitude variations at RF with a diode detector and an oscilloscope 8. The effect is clearly visible on several power meters 9. This AM causes some spectral re-growth, although this is tolerable So given all that I am beginning to wonder if the problem is due to filter ripple in the standard K3S 2.7kHz filter? I cannot think of anything else. I was considering buying an Inrad #718 filter. This is very critical for EME when signals are weak at the RX side, if you have amplitude variations and you are at the threshold of detection at the receiving station this can cause decodes to fail. This is more important on 6m EME than 2m where I have more margin. I think that this will be quite common, has anybody else got a K3S and the equipment to check and verify my observations? 73 Conrad PA5Y ______________________________________________________________ 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] -- This email has been checked for viruses by AVG. https://www.avg.com ______________________________________________________________ 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]
