David, Those who have mentioned "tuner loss" may or may not be correct - it all depends on the tuner. If the tuner is of the "T match" variety, it will have multiple points where it can show a match, but many of those "matched" points will result in high circulating currents in the tuner and high losses.
Elecraft tuners are "L-match" tuners, and do not suffer from those false tuning points - it will either match the load or it will fail. You LMR600 coax is very low loss and at frequencies below 30 MHz. I would offer that a 100 foot run could have an SWR as high as 5:1 and the loss would be acceptable. If your coax run is longer than that, or your SWR is higher, then, yes, I would feel more comfortable with a remote antenna tuner to keep the SWR on the coax down to a reasonable level. 73, Don W3FPR On 9/20/2012 3:59 PM, David Bunte wrote: > I have been trying to decide between the KAT500... and a remote tuner at > the base of my 30' vertical. I have measured the SWR on each band, at the > shack end of my 125' of LMR600. If I take that length, frequency and SWR > information and plug it into the chart for SWR loss of LMR600, I can see > what my loss is on each band... but I am not sure that tells the entire > story. > > Intuitively it seems that I want the ATU as close to the antenna as > possible. I could shorten my feedline to about 65'. I could mount an ATU > just inside my basement at about 30' from the antenna (and avoid a > weatherproof box - as long as the ATU does not need to be seen or touched), > or I could mount it at the base of the antenna, but that would be very much > more challenging. > > Is the SWR loss, based on my cable type, length & frequency all I need > consider, or am I missing something? > > Some people have told me that I need consider nothing else... others have > said that "tuner loss" is critical, and that will be greater than the line > loss. That sounds bogus to me, but I really don't know. > > I also know that the ATU in my K3 can make the rig very happy on 80 through > 6 with this antenna and 125' of cable... but I don't know if matching the > antenna at the end of 1', 30' or 65' will be harder, or easier. > > It was suggested that the TLW program by N6BV, that is packaged with the > ARRL Antenna Book would help, but I have not been able to figure out how to > use it, and can find no instructions for that program. > > Any and all help will be appreciated. > > Dave - K9FN > > > > > > On Thu, Sep 20, 2012 at 2:50 PM, Wayne Burdick <[email protected]> wrote: > >> It may be possible to remote the KAT500 with additional control >> firmware and an appropriate weather-proof enclosure. We haven't done >> any testing of this idea yet, but once we start shipping KAT500s, >> we'll work with a few customers who want to experiment with this to >> see what we can do to facilitate it. >> >> 73, >> Wayne >> N6KR >> >> >> ______________________________________________________________ >> 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 >> > ______________________________________________________________ > 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 > ______________________________________________________________ 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
