It's supported by electric fence insulators. Sent from my iPad Chuck, KE9UW (Jack for BMW motorcycles)
On Nov 15, 2012, at 2:00 PM, "N5GE" <[email protected]> wrote: > > I hope you have the ladder-line supported by fire-proof (ceramic) > insulators in the attic. > > Letting ladder-line touch anything combustible can start a fire. > > Amateur Radio Operator N5GE > ARRL Lifetime Member > QCWA Lifetime Member > > On Thu, 15 Nov 2012 13:22:55 +0000, "hawley, charles j jr" > <[email protected]> wrote: > >> I use a 1:1 balun at 450 ohm ladder line to get thru the attic and then 4 >> inch open wire outside to the dipole. >> >> Chuck, KE9UW >> Lionel Trains, TCA, LCCA, LRRC >> aka Jack, BMW Motorcycles BMWMOA #224 >> >> ________________________________________ >> From: [email protected] [[email protected]] on >> behalf of Brian Alsop [[email protected]] >> Sent: Thursday, November 15, 2012 7:02 AM >> To: [email protected] >> Subject: Re: [Elecraft] More KAT500 >> >> This seems so in many cases but it is very doublet length dependent. >> >> I ran one case in TLW with 45' of 450 ohm line that came out as 13 ohms. >> With a 4:1 balun you'd probably be dropping this further. High >> current and most likely not a match. >> >> The best suggestion is to model the antenna at height, get it's >> feedpoint impedances at bands of interest. Then go into a program like >> TLW with the 450 ohm line length and see what impedance results at the >> shack end. >> >> Adjusting 450 ohm length or doublet length may be required for an >> adequate compromise on the bands of interest. >> >> Without some analysis (or a proven design) it will be a crap shoot. >> >> 73 de Brian/K3KO >> >> On 11/15/2012 12:31, Jim Wiley wrote: >>> Ed - >>> >>> According to Elecraft, the KAT500 can match 10:1 SWR at 500 watts, on >>> any band 80 to 10 meters. It can also match 3:1 SWR at 1000 watts on >>> those same bands. The 160 meter and 6 meter capabilities are a bit >>> more limited, but it will still match a fairly wide range of loads. By >>> inference, 10:1 SWR at 500 watts between 3 and 30 MHz could result in >>> peak voltages in the range of 2250 volts and peak currents of 42 amperes >>> RF (one or the other, not simultaneously). This is pretty impressive >>> for a box that size. >>> >>> Using those voltages as limits, that indicates that the KAT500 could >>> handle power levels of about 250 watts at a 14:1 SWR. Any more could >>> result in damage. I would suggest replacing the 300-ohm line on the >>> antenna with 450-ohm ladder line, and inserting a 4:1 balun between the >>> antenna and the KAT500. I suspect that this will reduce the SWR >>> excursions, and may get you "inside the envelope" for what the KAT500 >>> can handle. >>> >>> A commonly used antenna is a doublet (dipole) fed with open wire, a 4:1 >>> balun, and a coupler. Most installations use a length of RG-8 coaxial >>> cable (typically 10 to 20 feet, but no longer than necessary) to "get >>> through the wall" - or from the coupler to the balun immediately outside >>> the building, then the open wire line connects to the balun at that >>> point and continues to the antenna. 450-ohm ladder line is usually a >>> better choice because it is designed for transmitting use, where 300-ohm >>> line is usually "TV lead-in" and not particularly suited for use at >>> higher power. Some transmitter rated 300 ohm line exists, and if you >>> have that type, it may work for you. As with all open-wire type lines, >>> keep the line at least 8" to 12" from metal objects if possible, more is >>> better, and avoid abrupt right angle turns. >>> >>> - Jim, KL7CC >>> >>> >>> >>> >>> >>> On 11/15/2012 2:41 AM, Goss, Ed wrote: >>>> Hi Jim, >>>> Thanks for the info. I am at work now and unable to post back to >>>> the group, but I appreciate the explanation. For the low bands, I use >>>> a 135 ft inv vee center fed with 300 ohm line, with a 1:1 balun near >>>> the shack. When my KAT500 starts to tune itself, I am seeing high >>>> SWRs, such as 14:1. After the auto tune cycle, it's 1:1. Perhaps I >>>> should be concerned that even with 100 watts, there would be >>>> conditions that overstress KAT500 internal parts with this type of >>>> antenna, but I want to be very careful about not damaging the tuner. >>>> I'm not quite sure how a user would know these limits, or if the >>>> KAT500 protects itself in any way. Perhaps the KAT500 is meant to work >>>> with antennas that present a somewhat better match to start with, like >>>> a typical 80 meter dipole which is cut for CW but the user wants to >>>> use all the way up to 4.0 MHz... >>>> --Ed--- >>>> >>> >>> ______________________________________________________________ >>> 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 >>> >>> >>> ----- >>> No virus found in this message. >>> Checked by AVG - www.avg.com >>> Version: 2012.0.2221 / Virus Database: 2441/5394 - Release Date: 11/14/12 >>> >>> >> >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2012.0.2221 / Virus Database: 2441/5396 - Release Date: 11/15/12 >> >> ______________________________________________________________ >> 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
