Hi Dave What can happen is that if you have common mode currents, then the RF on the feedline can affect the SWR readings on your radio. Do you have any mix 31 chokes on the feedline? I have seen this happen on my screwdriver antenna and the moment I choked the feedline and the DC control lines ALL my problems went away.
If this is on 40 or 80M and a screwdriver antenna, you will require a small shunt on the feed point to the antenna to improve the match. Again, you didn't mention which band this was happening on. 40M tends to be the problem band at times. Personally, I would recommend that you get the antenna tuned to 50 ohms and not use the tuner on the 3000. I think your performance might improve. I'm not exactly sure why things changed overnight, but that does happen and the is the magic of RF. It is likely a case your Screwdriver not in the exact same tuning place it was before. I doubt this is a radio problem at all. You can test it by seeing if you can tune into a resistive 25 or 100 ohm load. Just thinking out loud. Mike va3mw On Wed, Apr 16, 2014 at 10:37 AM, Dave Gomberg <da...@wcf.com> wrote: > A list member asked what kind of tunable antenna I had and it is a > screwdriver vertical. > > He also asked why I used TUN when my antenna was tunable and I do because > sometimes the antenna only tunes to 1.7 or so and I use TUN to improve the > match once the antenna is "tuned". > > > > ===== old mail below ==== > > > Twice now I have had a situation in which activating TUN on my Flex3K will > produce a wildly gyrating (up and down) SWR on my tunable antenna (or on > some bands, a solid 1.0 with no variation even with a wildly out of tune > antenna). > > The first time I tried rebooting the PC and totally powering off the radio > (no input voltage at all, not just no on button) for a few minutes, neither > helped, but powering everything off overnight "fixed" the problem. Then > all was fine for a week or so. > > Tonight it happened again. Is my radio broken? Should I send it back > for repair? Did I do something to screw something up? Help desperately > sought. Thanks. Dave NE5EE > > > > -- > Dave Gomberg, San Francisco NE5EE Programming since 1961 > All addresses, phones, etc. at http://www.wcf.com/ham/info.html > ----------------------------------------------------------------- > > _______________________________________________ > FlexRadio Systems Mailing List > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > Knowledge Base: http://kc.flexradio.com/ Homepage: > http://www.flexradio.com/ > _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
