Morgan, I looked for the 52:1 transformer at Balundesigns.com. No such animal found unless I am not looking in the right place.
73, Bill K9YEQ -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Morgan Bailey Sent: Tuesday, January 31, 2017 9:31 AM To: gliderboy1955 <gliderboy1...@yahoo.com>; Elecraft@mailman.qth.net Subject: Re: [Elecraft] 9:1 Balun Be careful in the 9 to 1 vs 4 to 1 vs 1 to 1. The 9:1 is generally an UNUN. When you run 100 watts or less most 1kw manufactured baluns or Ununs will take a wide variety of SWR if you are only running 100 watts. Because this thread is I believe about QRP the amount of power dissipated due to loss is not a factor. When you jump to 500 watts, core heating, saturation and breakdown are a risk. For instance, the W2AU balun that is manufactured as a center feed point for a dipole is only rated for the power at 1:1 SWR. In the printed literature the power rating drops off considerable as one goes to 2:1. I have personal experience with this particular balun when an 80/40 trap dipole was constructed using that balun and the Unadalla KW40 traps. Operating 40 was no problem as it was nearly 1:1 anywhere we operated [CW], but on 80 CW the bandwidth was much narrower, as to be expected and nearing the edges when we ran 500 watts into the antenna with the balun rated at 1kw, well, it's core heated up, SWR drastically changed, heating the core windings so much that the solder to the SO239 connecting the core to the coax melted off. We knew that the SWR was between 2.5-3:1 on the edges of the 80 meter range. So be careful. Additionally, I have little faith in stick Baluns or Ununs, I personally do not believe they are nearly as good as a Toroid constructed balun. Ununs seem to in my experience, tolerate wide ranges in SWR. I have used a 9:1 unun and their new 52:1 transformer for end fed antennas manufactured by Balundesigns.com with excellent results running 800 watts CW with little or no heating of the core and consistent results in a multiband environment. This was done using a 43, 53 and 87 foot end fed vertical/random wire/ inverted L and Half Square configurations. I have not modeled the pattern with NEC but I have compared it on Reverse Beacon Network [RBN] and I am definitely getting out. Full well knowing that Non resonant antennas are not as good as resonant ones, yes there is a difference in RBN reporting which favors the resonant, but, not always. This is because there is "funky lobe radiation" that can give a high report to just random one or two reporting stations and then the rest are 10-15 db less than the resonant over a wider area of report stations. This supports the pattern is not predictable, or as predictable as a resonant antenna installed correctly. Knowing we are addressing compromise installation for multiband usage, this I believe is acceptable. If you have goals of working or covering with gain and directivity, then there is no replacement for well designed and well installed resonant antennas. This is especially true in the competitive environment of contesting. When an antenna that is not balanced is used, the RF will seek a way to ground. Problems with feed line radiation, and RF in the shack are problematic. Using a counterpoise or limited radial system is recommended to provide the missing balance and a path to ground. This is generally not a problem at QRP levels but because a few 100 miliwatts of power coming back to the shack does not cause much problems but, jump that up to 10 or 100 watts and problems will surely make your life a living hell trying to keep the computer, keyboard, mouse cables connected and ATU from resetting and starting tuning cycle again and again. Best solution is to run resonant balanced antennas if one can, if one can't, invest in a few line isolators for the coax before it hits the shack and then have a good stock of Mix 31 ferrite beads for each cable in the shack, eg, usb, keyer, mic, speaker, keyboard, mouse...you get the idea. In the end, when one runs QRP power, balun/unun saturation and performance degradation, allows most anything to fly, jump the power to 100 watts, watch out, then to 800 watts...reforming injection formed plastic is in your future. Although, relative to this discussion, making an unun or balun with a T25 core and 32gauge wire will most likely produce the same disasterous results with 10 watts. LOL. Finally, Any antenna is better than No antenna. Morgan NJ8M On Tue, Jan 31, 2017 at 12:59 AM, gliderboy1955 via Elecraft < elecraft@mailman.qth.net> wrote: > What are the advantages/disadvantages of using a 9:1 balun v. using > the switchable Elecraft balun at 1:1 or 4:1 or no balun at all when > using a random wire portable? > Why 9:1? > Thanks > 73 Eric WD6DBM > > > Sent on my Samsung Galaxy S® 6. > ______________________________________________________________ > 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 Message delivered to > mbaileyc...@gmail.com ______________________________________________________________ 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 Message delivered to k9...@live.com ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
