See my comments below
-Tim -----Original Message----- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Jim Sent: Tuesday, August 25, 2009 9:38 AM To: FlexRadio@flex-radio.biz Subject: [SPAM] [Flexradio] flex 5000 antenna tuner questions 1) When I click on the ATU button to tune prior to transmitting sometimes the results are that SWR is too high to transmit. However, if I click on the ATU button a second time there is a brief delay while the 10w signal is analyzed and the results come back as an swr of 1.0. Does someone understand what is happening here? [Tim] Sometime the tuner achieves a bad match. The second time is a charm. 2) Does the ATU affect reception or is it only inline in the transmission circuitry? [Tim] It is only in-line in the TX signal path. The FLEX-5000 is a full duplex radio therefore it has separate RF signal paths for RX and TX. 3) What is best practice for using the antenna tuner? The manual in general tells how to do things but doesn't give examples as to best practice. [Tim] My best practice is not to use them. An impedance matching device at the radio (assuming you are feeding it with coax) only "presents" an impedance of your antenna system to something near 50 ohms at the radio itself. If you have high SWR in your antenna system for that particular frequency, that reflected power (loss) still exists in your antenna system. So all it allows your radio to do other than protect your finals or keep the RF power from folding back due to a high SWR, is to send RF down the coax to be converted to heat somewhere along the way and to get a little bit of signal (non reflected power) radiated. My preference for non-resonant antennas is to place the "tuner" (more aptly described as an antenna coupler) at the actual feed point of the antenna itself or at then end of a balanced feeder, like ladder or window line that is bust better suited to handle high SWR with minimal losses. But, if that is what you need to get on the air, then by all means do so. A little bit of RF transmitted is a WHOLE lot better than none at all. Thanks very much Jim WD7W _______________________________________________ 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.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to telli...@itsco.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.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to arch...@mail-archive.com
