Hi Charlie, the mast for his inv-V snapped during Hurricane Sandy and I attached the apex to the highest remaining part of the PVC mast that snapped, that I can reach up to. So for this moment, his Inv-V is more of a dipole with the apex 10-15 foot higher than the terminations. Next summer I'll wrangle the original assembly up for him and the apex will be another 30' higher than it is now.
I had to fell a few trees that were interfering with the wires and now he has a clear space with no more interference. So no high conditions here, my INV-L is based 20' lower than the basement 350' away and is at the edge of a salt marsh with the wire over the tree tops. The highest part of my vertical run is maybe 20' higher than the apex of his V is today. No possible way to put up anything taller for either of us, no towers allowed. It's still a nice location though on the end of Long Island sound. 73, Gary KA1J > Hi, Gary > > Should do fine! The W2DU balun is a good current-mode design by > someone who > knew what he was doing! > > As for 160, I do have a W2DU current mode balun, from Unadilla that > is > longer that the 80-10m version (more beads) but I never really > pushed it. I > did use it some n 80m. Actually on 160, I didn't really have need > for a > balun with the inverted L antennas that I used. I expect that the > application for a 160 m balun is most likely for guy s with high > dipoles and > inverted Vees, and really big delta loops. The w2DU balun will > workat least > as well as, and probably better than, the W2AU balun that it woud > be > replacing! > > Hope your dad enjoys it for many more years! :-) > > 73, > Charlie, K4OTV > > > > -----Original Message----- > From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of > Gary > Smith > Sent: Sunday, October 27, 2013 7:45 PM > To: Topband@contesting.com > Subject: Re: Topband: Balun Question > > Fellows, > > Thanks for the on & off list replies, I just got back from a weekend > away & read through them all. Part of me wants to just leave it as > is > but that's not practical, a good icing and the connections I made > will fail. Since I need something to relieve stress from the > copperweld and the weight of the coax, the W2DU 1:1 looks like it > ought to cover the issues. > > There's no telling when bad weather will hit and once there'ssnow on > the roof I'm not going up to work on anything so I need to do it > now. > He only operates on 80M phone using a Viewstar PT-2500A amp so the > W2DU 1:1 ought to be fine. Someday when I'm the one using the > station > I'll want to use it on 160 and I'm not sure how well that balun will > do on 160 but that's for another time. > > Thank you all for the thoughts and helpful suggestions. > > 73, > > Gary > KA1J > > > Unfortunately, optimum balun impedance and design really depends > > heavily on > > the application,. There is no magic design that works best for > all > > applications, and the issue is so complex that almost any > article > > falls > > short. > > > > For example, the 5000 ohms pure R will not work at 1500 watts > with > > all > > antennas. With a balanced feeder having a balun termination > > impedance of > > 2000 ohms, a balun would have 1732V RMS between conductors, and > 866 > > volts to > > ground. CM voltage would be 866 across a perfect balun if the > feeder > > were > > perfectly balanced. The 5000 ohm CM impedance balun would > dissipate > > 150 > > watts in the cores, far beyond what any reasonable core stack > would > > tolerate. The fact the antenna comes out of balance reduces the > heat > > somewhat, but this clearly is a case where we WANT a reactive > > isolation > > impedance to reduce heat. > > > > Making things worse, a half wave antenna fed through 1/4 wave of > > open wire > > might have an impedance of 6000 ohms or more. The above example > was > > for 2000 > > ohms! > > > > Without much effort, we can see why simplistic "always do this" > > rules just > > don't work in the real world. > > > > Every situation has to be case-by-case. > > > > 73 Tom > > > > > > > > > > ----- Original Message ----- > > From: "Tom Boucher" <t...@telemetry.demon.co.uk> > > To: "160 reflector" <topband@contesting.com> > > Sent: Friday, October 25, 2013 10:49 AM > > Subject: Topband: Balun Question > > > > > > > Gary KA1J - take a look at this excellent article on ferriste > > baluns by > > > GM3SEK: > > > > > > http://www.ifwtech.co.uk/g3sek/in-prac/inpr1005_ext_v2.pdf > > > > > > 73 > > > Tom G3OLB > > > _________________ > > > Topband Reflector > > > > > > > > > ----- > > > No virus found in this message. > > > Checked by AVG - www.avg.com > > > Version: 2014.0.4158 / Virus Database: 3614/6767 - Release > Date: > > 10/20/13 > > > > > > > _________________ > > Topband Reflector > > > > > > _________________ > Topband Reflector > > _________________ Topband Reflector