David, It's worth trying to figure out TLW. Steps are basically this for coax loss: 1) Select coax type 2) Input length 3) Input frequency.
The fun begins when one looks at the loss of the coax for various loads. Input 50 ohms first. That will give you the coax loss when matched. Then input other values and you will see total loss including the mismatch. Here are some examples using 125' of LMR600 20M matched .33 db 20M 10 ohms .805 db 20M 250 ohms .8 db 20M 500 ohms 1.43 db 10M matched .506 db 10M 10 ohms 1.19 db 10M 250 ohm 1.15 db 10M 500 ohms 2.0 db I wouldn't want to put a hacksaw to that beautiful (and expensive) coax to "improve things". Fittings aren't cheap either. Cutting it in half would pick up a max of 1 db in the above cases. In most cases it is less than 0.5 db. 1db is the minimum discernible signal level change a human can detect. TLW can do a lot more than the above. 73 de Brian/K3KO On 9/20/2012 19:59, 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<n...@elecraft.com> 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: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 > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2221 / Virus Database: 2441/5281 - Release Date: 09/20/12 > > ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2221 / Virus Database: 2441/5281 - Release Date: 09/20/12 ______________________________________________________________ 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
